Kiln Operation at WOODWEB's Knowledge Base

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Process Controls Versus Schedule Controls in Commercial Kiln-Drying Operations

Here's a technically informative, if somewhat contentious, debate about different approaches to computerized kiln control, and the role of human operators in the kiln-drying process. June 13, 2014

Developing Software to Calculate Wood Kiln Schedules

The wood drying process is complex, and involves many inter-related variables. So creating software to determine drying schedules is a challenge. June 13, 2014

Movement in Slabs Cut from Crotch Wood

Advice on sawing and drying crotch wood, with a view to managing warping and splitting. January 28, 2014

Hawaii Solar Kiln Show and Tell

A forum member from Hawaii shows his backyard solar drying kiln and gets some advice on improving it. May 27, 2014

Drying Spalted Alder

To halt the growth of spalting fungus, dry quickly and/or heat above 133°F. December 23, 2014

Techniques for Equalizing and Conditioning Lumber

The Wood Doctor explains how to complete the final two steps in the primary processing uh, process. 1998.

Kiln Control Technology and Drying Parameters

This mostly hypothetical discussion develops into a back-and-forth about whether wood stress should be used as a determining factor in kiln control systems. June 13, 2014

Solar Kiln Designs 4 -- Solar Heated, Lumber Dry Kiln Designs - Part 4

An in depth article by Gene Wengert and Luiz Carlos Oliveira

Whether to Thaw Frozen Wood Before Kiln-Drying

Here's a long and intense theoretical argument about whether frozen wood can be safely dried without thawing it first. June 13, 2014

Drying lumber - selecting the best method

Is a solar kiln the best choice for this startup sawmill? December 17, 2003

Sawdust as fuel

Building a sawdust-fired boiler to heat kiln and shop. November 18, 2002

Whether to Spray Wood During Kiln Warm-Up

Is it wise to spray wood with water or steam while the kiln is warming up? June 13, 2014

Solar Kiln Designs 2 -- Solar Heated, Lumber Dry Kiln Designs - Part 2

An in depth article by Gene Wengert and Luiz Carlos Oliveira

Causes and Cures for Stains In Dried Lumber

How to avoid various types of staining in kiln-dried lumber. 1998.

Controlling Drying Conditions and Monitoring Progress

Here's a lively, sometimes contentious, and very informative thread about how to ensure quality control when drying lumber in a variety of different kiln types with different control systems and instrumentation. July 16, 2012

Building a Small Drying Kiln

A long discussion of the considerations involved in building and operating a small backyard or garage kiln. August 8, 2008

Vacuum, Dehumidification, and Microwaves — in One Kiln?

Here's a long, highly speculative, but informative discussion of the concept of using microwaves, vacuum, and dehumidification for drying wood in a prototype kiln. April 20, 2011

Electronic RH sensors

Can electronic relative humidity sensors stand up to the elements in dry kilns? May 2, 2001

Turbulent Air Flow as a Factor in Kiln-Drying Operational Control

The Wood Doctor explains why controlling humidity and temperature, not managing airflow turbulence, is the way to maintain optimum drying conditions in the kiln. June 13, 2014

Brainstorming About Vacuum Kilns

Inquiring minds discuss why vacuum kilns are so expensive, how they work, and the possibilities of building your own — or even improving on the concept. July 30, 2007

Radio frequency -- vs. super steam vacuum

A discussion of these two kilns for drying large timbers. February 19, 2002

Solar Kiln Designs 3 -- Solar Heated, Lumber Dry Kiln Designs - Part 3

An in depth article by Gene Wengert and Luiz Carlos Oliveira

Wood and Water

An excerpt from Gene Wengert's book, "Drying Oak Lumber." May 31, 2001

Solar Kiln Designs 1 -- Solar Heated, Lumber Dry Kiln Designs - Part 1

An in depth article by Gene Wengert and Luiz Carlos Oliveira

Processing trees to lumber -- for the hobbyist

A primer on sawing and drying lumber for projects at home. March 13, 2001

Eliminating Wood Problems -- An Industry Review: 10 Ways of Eliminating Wood Problems

Gene Wengert explains why eliminating wood problems begins and ends with monitoring and controlling the moisture content (MC) in wood -March 18, 2000

Wood Drying Conditions and Musical Instrument Sound Quality

Instrument makers, musicians, and sawing and drying pros discuss whether kiln-dried or air-dried wood affect the way a musical instrument sounds. February 14, 2010

Processing Trees to Lumber -- for the Hobbyist and Small Business

Two experts share their secrets of success for small-scale milling operations. January 19, 2002

Alternative lumber drying techniques

Are freeze drying and RFV practical methods for drying lumber? April 25, 2001

Cupping and Bowing in Resawn Stock

Furnituremakers discuss drying issues such as casehardening that can cause lumber to move when ripped or re-sawn. April 18, 2015

Woodworking 101: The Basics

and shows how it can affect various production operations. 1998.

Kiln Drainage

Wood in a kiln releases water in vapor form. But condensation may occur in the kiln, requiring attention to drainage. April 2, 2015

A Small Kiln for Final Drying

A woodworker needs to get his already kiln-dried stock down to lower moisture content to match indoor end-use conditions. Here's detailed advice for equipment choice and drying methods for a small-batch wood-shop drying chamber. May 9, 2007

Is Kiln Drying to 7% Worth It?

Why kiln dry wood to 7% moisture content when it will gain moisture in storage? Here's an informative thread about proper drying targets and storage based on the intended end use of the lumber. December 31, 2013

Dehumidifier Kiln Advice

Detailed conversation about building, equipping, and operating a dehumidifier kiln to dry lumber. September 10, 2007

Troubleshooting vacuum kiln problems

An extensive discussion on vacuum pumps and vaporization of organic compounds in wood. February 28, 2001

Troubleshooting Mold on Oak in the Drying Kiln

A question about a mold problem leads to a discussion about process control and kiln conditions. June 13, 2014

Why is Walnut Purple Sometimes?

The purple color of some Walnut boards is natural. Here's more background with comments and observations from woodworkers. February 16, 2014

Measuring/Monitoring Moisture Levels

The hows and whys of monitoring moisture content in lumber. 1998.

Equations for Quantifying Heat Transfer, Evaporation, and Air Cooling in a Lumber Kiln

A set of equations that enable the user to predict the rate of drying, along with a discussion of the physics of kiln-drying. Good info here for the technically advanced and educated reader. June 13, 2014

Humidity Control, Warping, and Case-Hardening

Maintaining the right drying conditions is a tricky problem, and improper control can lead to defects in the lumber. January 2, 2012

Vacuum kiln drying

How do vacuum kilns work and how effective are they? (From WOODWEB's Sawing and Drying Forum) January 21, 2003

Air-Drying and Kiln-Drying 8/4 Oak

Experts and kiln owners discuss the proper drying schedule and the best equipment for drying thick Red Oak boards. August 13, 2014

Electric Moisture Meters

A guide for using portable electric moisture meters on lumber. May 3, 2001

Warp in Drying

Causes and cures for warpage when drying lumber. May 4, 2001

Self Air-Drying Versus Kiln-Drying

Carefully air-drying wood yourself may be preferable to trusting the load to a less-than-perfect kiln-drying operation. January 18, 2011

Home-Built Dehumidification Kilns

Here's a long discussion of small, inexpensive dehumidifier kiln design, including a consideration of the fire risks involved. September 17, 2012

Kiln drying for higher profit

Expanding a molding business to include kiln drying poplar. November 18, 2002

Advantages of vacuum drying

What does this leading-edge technology have to offer? April 9, 2003

Kiln Drying Large Timbers

An extended discussion of the technical issues involved in drying big beams for various uses. July 28, 2006

Achieving Sterilization with a Solar Kiln in a Humid Climate

A woodworker struggles to get his lumber pile hot enough to kill beetles. April 15, 2012

Drying Slabs in Tropical Conditions

Advice on drying uncommon lumber species in the jungles of Ecuador. August 15, 2011

Dry kiln operator's manual

The modern dry kiln is a unique product of research, development, and experience. It is the only practical means now in wide use for rapid, high- volume drying of lumber to conditions necessary for maximum serviceability in housing, furniture, millwork, and many other wood products. As part of our c ......

Drying Juvenile SYP

A few thoughts on the challenges of high-volume drying of 2x4 lumber cut from very small trees. June 13, 2014

Vacuum Kilns: Energy Use and Drying Times

A discussion of the performance you can expect in the real world from a vacuum wood-drying kiln. June 13, 2014

Troubleshooting Drying Stress

Some general instruction about the causes of drying stress for the owner of a dehumidifier kiln. April 2, 2013

Controlling Powderpost Beetles in Stored Lumber

Heat plus good hygeine are the standard recommendations, but this discussion also considers some alternative notions. November 14, 2009

Blue-Stained Pine Pros and Cons

Controversy simmers over whether blue stain is is a special value, a visual defect, or a mold liability risk. September 17, 2008

Home DH for drying lumber

Home dehumidifiers versus bought kilns for drying wood. September 2, 2002

Dry lumber kiln -- buying your first

Business and technical considerations when getting started in kiln drying. March 19, 2001

Exploring Alternative Kiln Technologies

Sawmillers try out, wonder about, and report on the Green Dri desiccant-based drying kiln from Japan. June 8, 2011

Why Insulate a Solar Kiln?

A long discussion delving into the mechanics of how a solar kiln creates proper conditions for drying wood. January 28, 2014

Drying rough-sawn timbers

A large outdoor project raises questions about drying large, rough-sawn timbers for long-term use. June 20, 2000

Honeycombing and Fresh Checking in a Newly Turned Newel Post

A woodworker's report of a honeycombing and checking problem leads to a good discussion of wood drying defects and how they manifest themselves. March 3, 2009

Setting Pitch in Douglas Fir

Temperature and time for setting pitch. February 28, 2004

Vacuum Kiln Principles

Vacuum kilns cause evaporation at low temperatures, but they still require heat — and that heat is tricky to supply because of the vacuum. Here's an explanation. July 29, 2011

Home-made house materials

Advice on sawing out the lumber to build your own house. February 28, 2001

Steam Conditioning Versus Mist Conditioning in Wood-Drying Kilns

Both are effective, and each has different quirks to consider. June 13, 2014

Pre-Surfacing Lumber Before Drying

Planed green lumber dries with significantly less checking. March 3, 2006

Eradicating an Insect Infestation

A load of insect-infested reclaimed wood may have contaminated a whole operation. What to do? April 20, 2011

Aging yellow cedar

Attaining the look of naturally aged yellow cedar. September 2, 2002

Acid Condensation Issues with Drying Kilns

This discussion of drying Oak for iron-and-wood furniture purposes takes an interesting detour into a discussion of acidic conditions in wood and kilns. October 15, 2010

Drying Ash Flooring

Kiln-drying is essential to kill bugs and achieve the proper low moisture content for stability in service. May 11, 2005

Steaming Walnut for Color

A description of Walnut steaming methods. June 13, 2014

Solar kiln glazing

Best material choices for a double layer of glaze. April 9, 2003

Moisture content oven tests

Microwave ovens versus drying ovens for MC testing. October 30, 2002

Drying cedar slabs -- and stepping up sawmill production

Effective drying and basic sawing with a scragg mill. September 2, 2002

Pricing for Kiln Drying

Sawmillers share numbers on kiln-drying service charges. November 14, 2009

Solar kilns - putting it all together

Compiling and analyzing information on the efficient design and construction of a solar kiln. November 22, 2003

Temperature, Humidity, and Drying

Some generic head-scratching over relative humidity and the heat required to dry wood under various conditions. April 10, 2007

Fan Speed for Solar Kilns

Advice on maintaining appropriate air flow over the stack in a solar drying kiln. March 26, 2013

Practical Ways to Reduce Drying Costs

Five tactics to consider for cutting the cost of drying a load of wood. June 13, 2014

Drying with Moderate Heat

Here's info on how various types of wood will respond to conditions in a home-built drying room that doesn't get much warmer than 120°F. There's a useful lecture here on how case-hardening occurs. May 16, 2008

Reconditioning of Collapsed/Washboard Timber

Collapse of sawn lumber during drying is a rare event. Steaming may help prevent the problem, and to some extent cure it. January 12, 2015

Causes and cures for sticker stain

The Wood Doctor weighs in with comprehensive information about the causes and prevention of sticker stain. 1998.

Using a Corn Drier as a Kiln

Lumber drying is a controlled process, that an agricultural corn dryer probably cannot accomplish correctly. February 15, 2009

Air-Drying Versus Kiln-Drying for High-Value Wood

Done right, kiln-drying gives you better control over quality. June 9, 2007

Drying burly slabs

Keeping oak slabs from cracking. January 16, 2002

Straightening Thin Dowels

A woodworker struggles with a crooked dowel problem in a mass production setting. October 1, 2010

Mobile Wood-Burning Kiln

Is a wood-fired, movable lumber drying kiln feasible? Here are some ideas. July 13, 2006

I've Got that Shrinking Feeling

Specific information on lumber shrinkage during the drying process. Includes 'typical shrinkage' tables for red and white oak. 1998.

Conditioning: Relieving those stresses

Try these solutions to a stress-free wood inventory. November 29, 2002

Vacuum Kilns - Pros and Cons

Testimony from operators who have used vacuum kilns. May 11, 2005

"Intermediate Conditioning" in the Drying Kiln

Is it a good idea to add moisture to a kiln for a period during the middle of the drying cycle, in order to relieve casehardening stress? June 13, 2014

Moisture and Wood Movement In Kiln-Dried Versus Air-Dried Lumber

In principle, wood's response to moisture changes is the same, no matter how the wood was dried. In practice, there may be a slight difference. July 23, 2014

Drying Eucalyptus

Eucalyptus is a fussy wood to air-dry or kiln-dry. Here are some clues about its character. October 14, 2006

Automatic vents for solar kiln

Can vents be left open at night or must they be controlled? (Sawing and Drying Forum) April 29, 2003

Dealing with Insects in Furniture

Advice on heat-treating a Persimmon hutch that is being attacked by beetles. February 14, 2010

Is it Worth Kiln-Drying Firewood?

Considering the cost of kiln construction and energy inputs versus the value of extra-dry firewood, it's hard to see how the dollars make sense. January 27, 2008

Using Outdoor Cold for Drying Dehumidification

Unlike a powered dehumidifier, a cold kiln wall dumps heat to the outdoors, and so expends energy just as venting does. Here's a long discussion of alternatives to heat for kiln drying, and why they're mostly not practical. April 10, 2007

Air-drying oak

Can a suitable MC for cabinet construction be reached? February 6, 2002

Bowing in Pine Staves After Planing

Here's a good explanation of why lumber may move after being planed — and why that is not easy to correct. January 20, 2010

Logging Equipment

Essential equipment for a small-scale logging operation. April 25, 2001

Choosing a Moisture Meter

A well-informed discussion comparing the cost and characteristics of various pin and pinless moisture meters. October 11, 2012

Sizing Up a Kiln

This question about how to assess the worth of a used kiln leads to a discussion of kiln technology in general, including the different requirements for drying softwoods and hardwoods. October 17, 2012

Drying wood in a tent

Recommendations on how to use the sun's rays and a plastic tent to dry lumber. November 7, 2001

"Safe Drying Rate" and a Dehumidifier Kiln

A discussion of how to apply "safe drying rate" calibrations with a home-built dehumidifying kiln. January 27, 2007

Temperature and Humidity Measurement Accuracy and Drying Kiln Control

Instruments have limited accuracy. So to fine-tune a kiln's performance, you have to monitor the drying progress by weighing wood samples. July 29, 2012

Pricing for Kiln Drying Lumber

Here are pictures of a drying kiln building under construction, with commentary on how to charge for drying wood with a dehumidifier kiln. December 8, 2012

Optimizing Fans in a Solar Kiln

Advice on housings and shrouds for kiln fans. December 31, 2013

Preventing Insect Infestation in Lumber Production

Pesticides have limited usefulness and significant hazards. Good yard hygeine and application of heat are the more practical choices. February 14, 2006

Converting A Shipping Container to a Drying Kiln

Design, construction, and operation info from folks who've done it. February 26, 2005

Is Vacuum Dried Wood Stronger?

With so many variables to control, it's hard to be sure whether any particular drying system gives better results in terms of wood properties. October 29, 2012

Drying Oak Lumber: Step 7, Storage

The Wood Doctor discusses how to protect dried lumber from damage during storage. August 27, 2012

Over-Drying and Wood Quality

Kiln operators discuss what happens to lumber when you overshoot your moisture content target. February 14, 2006

Operating Solar Kilns on a Rainy Day

On rainy days, close the vents and switch off the fans. March 16, 2015

Water and Wood

Some options for measuring moisture in lumber during the kiln-drying process. 1998.

Cupping of newly cut lumber

Why would all the lumber in one kiln load cup toward the sapwood? January 16, 2002

Mixed-Species Loads and Moisture Equalization

Kiln-drying Spruce and Fir together creates difficulty, because they dry at radically different rates and because there is moisture transfer between boards. June 13, 2014

Case Hardening Explained

A semi-technical discussion about how the wood drying process can create stresses between interior and surface wood layers — and about how to reduce or prevent that situation. January 19, 2012

Pros and Cons of Sawing Your Own

A solo cabinetmaker wonders if he should mill his own lumber on the side. March 14, 2005

Measuring Moisture Gradient at the End of Kiln-Drying

Core and shell moisture content can be important things to know in certain cases, but it's usually not vital information for running the kiln. June 13, 2014

Hairline Cracks in Kiln-Drying Cherry

Checking in Cherry appears as a fine crack, and is the result of too-fast air-drying, not kiln-drying. April 15, 2012

Finish Over Air-Dried Pine

Soft resin and volatile natural solvents in softwoods will interfere with finishes unless the wood is kiln-dried at a high enough temperature to "set the pitch."August 17, 2009

Double-Checking Moisture Content

You can check your moisture meter by drying wood samples and weighing them, but the method has its own uncertainties and imprecisions. August 29, 2006

Longitudinal Versus Tangential Stress

A discussion of how to evaluate and troubleshoot drying stress in kiln-dried lumber. June 13, 2014

Redrying 4/4 Hard Maple

Tips for re-drying a load of wood that got wetted by rain, without incurring damage. December 31, 2013

Dehumidification Kiln Conditioning Without Steam

Techniques and equipment for producing a balanced environment inside your kiln. May 11, 2005

Stickers and sticker shadow

A discussion on synthetic and traditional stickers, and an explanation of reverse sticker shadow. May 30, 2001

Drying Lodgepole Pine in Colorado

Detailed advice on air-drying and kiln-drying lodgepole pine (some logged green and some killed by beetles). April 21, 2008

Solar Drying Kiln Q&A

Basic questions and answers on vent sizing and temperature conditions in a solar kiln. January 18, 2011

Heat Up Rate in Lumber Drying

Most wood-drying situations don't require careful control of the rate at which the load heats up. June 13, 2014

Stain Spots on Soft Maple after Kiln Drying

This particular problem was a chemical stain, but the thread also has an interesting discussion of beetle damage. June 13, 2014

How to Prevent Drying Stress

A quick explanation from the Wood Doctor of what causes drying stress, and how to prevent or reduce it. August 15, 2011

Mesquite Lore

Texas woodworkers share their knowledge of Mesquite wood. August 21, 2006

Monitoring Progress in a Dehumidifier Kiln

Collecting and measuring the removed water is not a reliable way to gauge drying progress, especially when drying mixed thicknesses of wood. June 4, 2012

The Importance of Air Velocity in Drying

How air speed through the kiln affects lumber seasoning. July 20, 2002

Steaming, Drying, and Honeycomb in Walnut

Bacterial infection as well as steamer and kiln settings may have caused reported honeycombing at one end of thick Walnut boards. June 18, 2009

Calculating airflow in a kiln

Quantifying airflow through lumber stacks. April 2, 2002

Air-Drying Time and the Need for Conditioning

If you air-dry lumber for long enough, it won't experience drying stress in the kiln; but you do risk lumber degrade. July 30, 2007

Vacuum kilns

Choosing between a vacuum and dehumidification kiln. July 24, 2001

Fan Motor Switch Tripping Problem in a Dehumidifier Kiln

Troubleshooting a fan performance issue in a dehumidifier kiln. October 15, 2010

Rates for sawmilling/kiln-drying

Sawyers post their individual rates for sawmill and kiln-drying services. June 27, 2000

Wet Pockets in Kiln-Dried Wood

Bacterial infections can cause streaks of 30% moisture content in wood that is mostly at 7% MC. March 4, 2009

Tension Set and Lumber Conditioning

Advice on remediating curved lumber after resawing, with a discussion of why "tension set" occurs and how the effect can be reversed. October 19, 2013

Drying rates for hardwood lumber -- How fast can you dry?

Facts and stats for time-sensitive drying that will produce quality lumber. November 29, 2002

Boosting a Solar Kiln with Propane Heat

Thoughts on modifying a solar kiln with supplemental propane heat to kill bugs and set pitch. April 30, 2009

Dead Standing Douglas Fir: Is It Dry Already?

A discussion about the useability of wood from dead standing tree logs without further drying, and a little bit of kiln-related history. April 27, 2007

Promoting blue stain

How to promote this visual effect in a stack of red pine. March 21, 2002

Hard Maple for Baseball Bats

Info about sawing, drying, and grading maple bat billets. October 2, 2005

Hardwood Lumber Kiln Schedules

Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. 1998.

Troubleshooting Low Humidity During Conditioning

A cold spot or air leak in the kiln can prevent the air from reaching the target humidity for conditioning. June 13, 2014

Air-Drying and Kiln-Drying Thick Maple

Drying 12/4 hard Maple, a kiln operator walks a fine line between checking and staining. Here's more. July 29, 2011

Dealing with Variable Moisture Content in the Kiln Load

Mixed loads with varied moisture contents are an age-old problem with no easy solution. But here are some ways to approach the situation. June 13, 2014

Red oak drying problems

Troubleshooting a problem of varying moisture contents in loads of kiln-dried red oak. March 20, 2001

Drying Rewetted Kiln-Dried Lumber

How to render kiln-dried lumber, which has been rewetted due to flooding or excessive humidity, useful once again. 1998.

Air-Drying and Kiln-Drying Methods for Wide Plank Flooring

A discussion of the most cost-effective and quality-conscious way to dry wide planks for use as flooring. September 6, 2010

Size effect on shrinkage

Are traditional shrinkage values applicable to drying large cants? May 9, 2001

Checking in Oak

A discussion of kiln conditions and other factors that can cause Oak to check while drying. October 29, 2008

Sawdust on stacked wood

Should sawdust be cleaned off before stacking and drying? October 15, 2001

Holly Staining: Fungus or Pigment?

Holly stains if it's not dried quickly and properly. But what's the real cause? A scientist weighs in on samples collected by a sawyer. July 12, 2005

Drying Logs in a Vacuum Kiln

Heavy timbers dry rapidly in a vacuum kiln. October 26, 2013

Bug Control in Ash and Oak

Details about the heat conditions required to kill insects in a load of lumber being kiln-dried. March 28, 2012

Powderpost beetles in hardwood beams

Is there any way to get rid of powderpost beetles riddling oak beams with holes? November 7, 2001

Moisture variance in red oak

Basic drying procedures and a discussion of bacteria in red oak. February 13, 2001

Elevated Moisture Readings after Planing

Wood that is not uniformly dry will read higher after planing; and the results vary between pin meters and pinless models. June 4, 2012

Miniature Solar Kilns

Very small solar kilns are indeed practicable, if you only need to dry small pieces of wood. December 31, 2012

Dehumidification drying of thin stock

Simple drying methods for small, thin stock. (Sawing and Drying Forum) March 23, 2003

Running a Solar Kiln

Advice from old hands on operating a solar kiln. August 22, 2005

Is Your Meter Running?

The value of the moisture meter when drying of oak lumber. 1998.

Selecting Fans for a Solar Kiln

Advice on picking fans that will move the right amount of air and not fail from overheating. February 8, 2008

Casehardening, Checking, and Warping

Dry lumber that warps when resawn offers a lesson about casehardening and its effects. May 27, 2008

Kiln-Drying Reclaimed Heart Pine

A few simple tips for a new kiln operator. October 2, 2005

Treating Air-Dried Wood with Pesticides

Surface-applied pesticides may be dangerous or even illegal, and will probably do no good. Instead, heat-treat wood to kill bugs. February 14, 2006

Lumber Conditioning Advice

Info on mixed loads, re-wetting dried lumber, and related topics. September 25, 2014

Drying Oak Lumber: Step 1, Assessing the Raw Material

The first step in drying Oak is to know the characteristics of the lumber you're planning to dry. July 29, 2012

Reconciling Contradictory Moisture Readings

A pin-type moisture meter and a pinless moisture meter disagree during a quality-control check. What's going on? June 16, 2014

Fanless Solar Kiln?

Natural convection is not a practical way to power air flow through a drying kiln. August 1, 2011

Managing Airflow in the Pre-Dryer

Advice on using temporary baffles to keep air flowing through the remaining stacks as some wood is removed. June 13, 2014

Lowering Wood Moisture Content

A woodworker has some lumber at 12% moisture content that he wants to dry down to 9%. Here are some quick and cheap ways to accomplish that. October 19, 2013

Should Hardwood be Air-Dried Before Kiln-Drying?

A discussion on the best drying schedule for maple, white ash, black ash, beech, cherry, and birch. December 1, 2005

Comparing moisture meters

An assessment of the performance of pin and pinless moisture meters made by major manufacturers. July 11, 2000

Sawing and drying mesquite

Dealing with many-trunked mesquite trees. February 6, 2002

Dump Cycle Kiln Drying

A discussion of the value of periodic high-volume venting during the kiln-drying process. July 13, 2006

Kiln Humidity Monitoring: In-Flow or Out-Flow?

Standard practice is to monitor the characteristics of air before it enters the pile, but monitoring exiting air could work under some circumstances. July 29, 2012

Pros and Cons of Radio-Frequency Vacuum Drying

RF vacuum drying tends to be complicated, expensive, dangerous, and unreliable. February 15, 2015

Air Flow Meters for Kilns

A discussion on the state of technology for monitoring airflow inside a kiln during drying, and about whether the data is useful in any case.June 13, 2014

Drying Wood in a Shipping-Container Kiln

Insights on using a dehumidifier kiln built from a shipping container. December 11, 2007

Moisture Monitoring in Kiln Operations

A technical discussion of how to keep track of drying conditions in a kiln in real time. April 18, 2010

Digital hygrometers

Kiln operators discuss options for measuring conditions in their lumber drying and storage facilities. July 26, 2000

Economics of End-Coating to Prevent Checking

If you look at the numbers, sealing log or board ends is worth the cost. June 13, 2014

How did our forebears dry lumber?

How lumber was dried for furniture construction prior to the introduction of kiln drying. November 21, 2000

Bug Holes in Air-Dried Maple

Advice on a lumber insect infestation. March 4, 2009

Rx For Planer Splits

The five main causes for splits in lumber during roughmill planing. 1998.

Steaming Before Kiln-Drying: Good Idea?

Steaming wood before the drying cycle may or may not be wise. But in any case, the idea is patented. June 13, 2014

Drying wood for musical instruments

A primer on various lumber drying techniques as they relate to musical instrument construction. 1998.

Yellow Streaks in Claro Walnut After Kiln-Drying

Bacterial infection inhibits drying in walnut, leading to visible discoloration that is revealed when the wood is planed. December 11, 2007

Humidity Control in a Kiln

A kiln operator gets advice on airflow and humidity settings. April 27, 2007

Selecting a Moisture Meter

A discussion of desirable attributes for a moisture meter used for kiln-drying quality control. June 30, 2007

Drying Half Logs for Benches

Unfortunately, large logs crack as they dry. It's unavoidable. March 16, 2015

Ideas for weighting stickered lumber

Options for applying weight to stickered, drying lumber are offered. August 10, 2000

Monitoring Moisture Content During Kiln Drying

At the critical early stages when wood moisture content is high, moisture meters are not accurate. Here are tips on keeping track of moisture throughout the drying process. May 17, 2011

Fiber saturation point: not an issue

Why the fiber saturation point is not a critical element in proper kiln drying practice. September 26, 2000

Drying Oak Lumber: Step 6C, Equalizing and Conditioning

Equalizing and conditioning result in consistent lumber with minimal drying stresses. But this step adds time and expense. August 27, 2012

Dehumidifier Kiln "Hanging Up"

Dehumidifier kilns sometimes stall as moisture content readings get closer to the target. An extra shot of heat can help a lot. July 3, 2008

Producing Drying Defects on Purpose

A client requests surface checks in his kiln charge of white oak. Should the operator oblige? May 11, 2005

Does Vacuum Kill Insects?

Nope, you need heat to kill bugs in wood (and don't call them bugs). March 4, 2009

Determining MC by weight

Tools and techniques for measuring moisture content by weighing lumber cuttings. January 4, 2001

Troubleshooting a Dehumidifier Kiln

A newly acquired (but secondhand) dehumidifier kiln has some performance issues, and the Sawing and Drying forum offers advice. March 26, 2013

Drying Walnut Crotch Slabs

A light coat of sealant? Or a slow, careful spell in the kiln? February 26, 2005

Measuring Air Velocity in a Kiln

Airflow is usually measured exiting the kiln. Here are some details on good practice. June 13, 2014

Beetle Troubles

Tips on dealing with lyctid (powderpost) beetles and the less troublesome anobiid beetle. April 27, 2007

Drying Fast-Growth Hybrid Poplar

Advice on how to address cupping of hybrid poplar during air-drying and kiln-drying. January 29, 2009

Adding Supplemental Heat to a Solar Kiln

Extra heat for a solar kiln could help in some circumstances, but hurt in others. February 12, 2007

Understanding Drying Stress in Wood

A complaint about cupping in mahogany door stiles after machining leads to a discussion of what causes drying stress and related movement in kiln-dried wood. June 23, 2006

Phytosanitary Standards for Lumber Export

A little information about heat-treating and labeling requirements for wood pallets and lumber destined for export overseas. July 26, 2010

Troubleshooting Unexpected Honeycombing and Checks

A kiln operator seeks an explanation and some advice after a batch goes badly. January 12, 2015

A Small Solar Kiln

Report and photos of a small, just-finished solar kiln. November 8, 2007

DH Kiln Drying

References for DH kiln drying instruction

Drying Pressure Treated Lumber

Advice on the complications involved in kiln-drying preservative-treated lumber. April 2, 2013

Storing Maple in Partially Dried Condition

A woodworker gets advice on the feasibility of maintaining wood at 25% moisture content for use in drying operations. January 8, 2010

Planer is tearing-out -- on white oak, but not red

What could be the culprit when a planer is tearing out on one type of oak, but not another? June 14, 2000

Color Variations Induced by Drying Wood

A discussion of how the kiln drying process can result in a variety of wood colors. June 13, 2014

Conditioning Lumber to Relieve Drying Stress

Tips on steaming lumber at the end of the drying cycle to reduce stress. May 15, 2012

Is Dehumidifier Kiln Wastewater Safe?

Don't assume that it's safe to dump kiln water to the environment. There could be some contamination. March 10, 2008

Whether or Not to Condition Lumber after Drying

It's not always necessary to condition a load of dried lumber at the end of the drying cycle — only sometimes. February 22, 2011

Home-built solar kiln

Fully illustrated details of a solar dry kiln. May 5, 2003

Drying Time for 6/4 Red Oak

Here's a quick technical look at the factors affecting kiln drying 6/4 Red Oak, including kiln type and initial moisture content. Air drying may be more cost-effective. July 16, 2012

Cupping in Wide Boards from Drying

A discussion of the processes that make boards cup during kiln-drying. February 27, 2013

Making a Drying Kiln from an Insulated Truck Body

This conversation touches on the quantity of heat needed to dry a load of wood, the advantage of using a dehumidifier, and the possible issues with corrosion. April 18, 2015

Conditioning DH-kiln-dried white oak

July 18, 2000

Don't send a home dehumidifier -- to do a commercial kiln's work

Are domestic dehumidifiers adaptable for use in drying small quantities of lumber? March 12, 2000

Stickers for green lumber

Where do sawyers get their stickers? November 7, 2001

How Fast Does Kiln-Dried Oak Regain Moisture?

Advice on how to measure the increase in moisture content of wood stored in a covered shed after kiln-drying. June 13, 2014

Moisture Variations in Dried Lumber

"Wet pockets" in kiln-dried lumber, or occasional wet pieces of wood in a load of dried lumber, are an unacceptable defect.June 13, 2014

Drying Willow in a Solar Kiln

Challenging scenario: a tricky wood to dry and a difficult kiln to control. February 14, 2010

Drying Bowl and Platter Blanks

Rough-turn the pieces before drying for better results. August 30, 2005

Energy Cost of Vacuum Kilns

Estimates of the electricity and heating fuel consumption and cost for vacuum kiln operation. June 28, 2006

Dry Kiln Information Resources

A list of clubs, organizations, books and publications providing information about drying lumber for use in woodworking. 1998.

Controlling Overheating in a Dehumidifying Kiln

How to cool off a dehumidifier kiln that is overheating just from the compressor heat. March 4, 2009

Vacuum Dried Red Oak

Achieving quality and color. May 19, 2004

Power Venting a Kiln

A discussion of the ideal location for powered vents for a large drying kiln. May 14, 2006

Solar Kilns and Wood Sterilizing

Solar kilns don't get hot enough to sterilize wood (for that you should have an artificially heated supplemental chamber).July 7, 2011

Managing Fungus on Cedar

Advice on handling and cleaning a Cedar slab that wasn't properly dried and now harbors fungus. October 19, 2014

Solar Kiln at Work

Here's a look at a newly completed backyard solar wood drying kiln with its first load of lumber. March 28, 2012

Geothermal dehumidification kiln

Can water piped from below ground help with dehumidification? July 24, 2001

Minimum Sticker Thickness

How thin can stickers be in order to maximize kiln capacity without creating drying problems? May 11, 2005

Solar kiln instruments

Advice on controls for monitoring a solar kiln. October 2, 2001

Sticker Thickness

Three quarters of an inch is the practical minimum. April 10, 2005

Alternatives to Fumigating Furniture for Bugs

if you're careful. April 24, 2014

Troubleshooting Cracks in Kiln-Dried Live Oak

Experts attribute a cracking problem in 8/4 Live Oak slabs to drying the wood too fast at too low humidity. August 26, 2008

Fans Size and Drying Kiln Dimensions

Considerations regarding fan capacity, kiln size, and lumber pile size in a dehumidfying kiln. January 25, 2010

Steaming Walnut

If you do it properly, steaming walnut brings color to the sapwood without destroying the figure in the heartwood. May 11, 2005

Shopping for a Dehumidifying Kiln

If you consider getting a European-made dehumidifying kiln for use in the U.S., make sure it's compatible with U.S. power supply voltages. June 16, 2014

Lindane

Information on Lindane, a pesticide used to control powderpost beetles. June 21, 2000

Challenges of Drying Eucalyptus

Many ways have been tried to prevent Eucalyptus wood's tendency to warp and check, but none have proven to be highly successful. February 29, 2012

Maple Color and Drying Conditions

Maple can turn gray as it dries. If you want white wood, you have to carefully control the kiln conditions. July 30, 2007

Heat Control in a Dehumidifier Kiln

Understanding how supplemental heating and the compressor's heating effect interact in a dehumidifier kiln. February 15, 2009

Growth Stress End Checking

Log characteristics can cause checks to open up, even when ends are coated and drying conditions are correct. February 19, 2006

Sawing and Drying Red Gum

Advice on how to process Red Gum and comments about its marketability. January 2, 2012

Glazing for a Solar Kiln

Clear glazing works much better than translucent white, a solar kiln owner discovers. December 15, 2005

Oven-Drying Wood for Moisture Content Testing

Information on the correct methods for oven-drying wood samples to determine moisture content. September 27, 2008

Sawing wood for house-framing

The basics of sawing and drying lumber to by used in constructing a house. January 3, 2001

Troubleshooting Wood Discoloration with High Pressure Steam Equalization

Advice on setup details to keep liquid water out of the situation when using high-pressure steam to condition wood in a kiln. June 13, 2014

Moisture Meter Quality and Price

What makes a good moisture meter? March 3, 2006

Cause of Loose Knots in Pine

Looseness or tightness of a knot in Pine is a characteristic that is formed during tree growth, not a product of the kiln process. June 13, 2014

Burlwood Rocking Chair Examples

Check out two beautiful rockers — and the "before" picture of the sawn burls they were made from. May 31, 2010

Wood weight and highway transport

How to accurately estimate the weight of a truckload of air-dried lumber to assure compliance with trucking regulations. Includes access info for resources. August 1, 2000

20 Steps to Drying Hard White Maple

The Wood Doctor's 100 percent guaranteed, sure-fire, no-snake-oil method for successfully drying hard white maple. 1998.

Air temp, relative humidity and MC

How much moisture can air hold, and what is the effect on drying lumber? July 4, 2000

Bugs in air-dried ash

Can a stack of ash be saved from an infestation of powderpost beetles? June 20, 2000

Unusual Checking in Hard Maple

A case where every board sawn from a Maple log has checks through the middle. What's going on? February 17, 2012

Sizing Up Dehumidifier Kilns

Thoughts on the objective characteristics to consider when evaluating which dehumidifier kiln is right for you. April 11, 2008

Drying Schedule for Red Oak

Advice for a kiln operator on drying rates and humidity and heat settings for drying Red Oak in a dehumidifier kiln. October 3, 2009

Hardness and Kiln-Drying Temperature

Higher drying temperatures affect the hardness and machinability of wood. December 12, 2008

Time to Kiln-Dry 12/4 White Ash

Estimates on the time required to dry a load of White Ash sawn three inches thick. March 28, 2010

Kiln Drying Color Change

Experts and sawyers discuss the various reasons wood from the same batch might end up with slightly different colors. September 6, 2010

Venting and Fans for a Solar Kiln

A quick expert explanation from the Wood Doctor of how and why vents and fans are used in a solar wood drying kiln. April 20, 2011

Drying Siberian Elm Slabs

Prone to warpage and bug damage, Siberian Elm is tricky wood to dry. March 31, 2008

Slow Drying at the End of Dehumidification Kiln Run

If drying slows or stalls at close to the target moisture content, a small amount of added heat is appropriate. December 8, 2012

Attic drying and over-drying

Can wood be over-dried in your attic? October 15, 2001

Keeping lumber flat during drying

Advice from Professor Gene Wengert on drying lumber in order to produce flat, true boards. December 12, 2000

Kiln Drying in a Heat Wave

When conditions are wrong, a solar kiln can easily be too hot for good results. Here are tips on controlling drying conditions during hot weather. May 15, 2012

Protecting Fresh Wood from Bugs

Chemical means have drawbacks and are not very effective. So good drying and careful hygeine in the the yard are your best methods for keeping wood bug-free. April 20, 2011

Troubleshooting Warpage with Kiln-Dried Cherry

Why did a load of Cherry boards warp in the kiln? May 16, 2008

Worm Holes in Mahogany

Worm holes aren't always considered as a defect in Mahogany, but they do leave you wondering whether the critters will come back. July 30, 2007

Drying Technique and Wood Hardness

Those in the know describe the effects of case-hardening (a drying defect) and how to diagnose it, as opposed to hardness that would affect machinability of wood. July 30, 2007

Sycamore Drying Schedule

Advice on a drying schedule for Sycamore in a dehumidifier kiln. August 8, 2008

Honeycomb and Checking with Mixed Kiln Loads

Advice on limiting honeycomb defects in Red Oak during kiln-drying operations. September 6, 2010

Setting Pitch in a Dehumidifier Kiln

DH kilns may not reach the temperatures required to set pitch in wood. Be careful of CO poisoning when supplying supplemental heat. December 11, 2007

Adjusting Moisture Meter Readings for Hot Lumber

Moisture meters aren't accurate when used on hot wood fresh from the drying kiln. You have to allow for that. June 13, 2014

Troubleshooting Bow in Kiln-Dried Cherry

A discussion of the causes and possible cures for bowing of lumber. November 14, 2009

Dehumidifier Kiln Drying and Insects

Cooler temperatures in a DH kiln aren't a reliable way to kill all insects, but the dryness will get some of them. May 18, 2010

Reducing warp during kiln drying

Weights? Restraints? What are the best methods for preventing warp in boards near the top of the drying stack? February 13, 2001

Power Vent Systems on a Dehumidifier Kiln

Comments on the practicality of automatic powered vent louvers on a dehumidifier kiln. March 31, 2008

"Caramelizing" Issues when Drying Hard Maple

Here's a technical explanation of the chemical process that makes some wood turn brown during kiln-drying. December 12, 2008

Drying Schedule for 8/4 Walnut

Be careful when drying thick Walnut — drying too fast can damage the wood. January 14, 2013

Yellow discoloration in oak

Causes of yellow staining in kiln-dried oak are discussed. October 2, 2001

Lumber Drying Costs

The price of kiln-drying services varies by location. Here, pros discuss the factors that contribute to the cost. August 23, 2005

Drying Heavy Oak Timbers

Expect a lot of checks and cracks. October 2, 2005

Moisture content for exterior doors

Determining the appropriate MC for lumber that will be exposed to vastly different humidity levels. November 14, 2001

Drying and Processing Mulberry

A slow-drying wood, Mulberry requires special handling. May 18, 2010

Rate of Wood Moisture Gain from Ambient Humidity

How long will it take for furniture stored in an unconditioned warehouse to equilibrate with the ambient moisture conditions? April 18, 2010

Checking for Drying Stress in Kiln-Dried Lumber

A kiln owner learns how to properly test his product for drying-induced stresses. June 30, 2007

Peruvian Walnut Drying Defects

Peruvian Walnut shows wide variability, which can create drying and machining difficulties. June 13, 2014

Excessive Checking in 8/4 Honey Locust

Slower drying under moister conditions might have helped this load. August 31, 2005

Dry-Bulb and Wet-Bulb Settings and Kiln Control

Tips on temperature and humidity control in kiln-drying operations. March 26, 2007

Basement drying basics

The Wood Doctor prescribes proper drying procedures for a small batch in a basement. June 21, 2000

Drying Beech in a Dehumidifier Kiln

Beech needs an aggressive drying schedule, similar to Oak or hard Maple. January 25, 2013

Optimal width when milling lumber

Milling lumber to the ideal width, and stacking for drying without warpage. December 6, 2000

Kiln velocity and sticker thickness

The necessary volume and velocity of air exchange, and sticker size, for a small dehumidification kiln are discussed. November 29, 2000

Supplemental Heat for a Solar Kiln

Kiln owners suggest ways to "bump up" the heat at the end of a drying cycle. October 20, 2005

Energy Cost for a Vacuum Kiln

An analysis of the energy bills involved in operating a vacuum kiln. July 13, 2006

Lumber Acid Content

A closer look at when lumber or bark might release tannic acid or acetic acid. April 17, 2009

Solar Kiln Q&A

A few basic questions about solar drying kilns, answered. December 8, 2012

Setting Pitch in Southern Yellow Pine

You have to heat the wood to 160°F to set all the sap. Otherwise it will ooze out, even through shellac or other sealers. February 9, 2008

How to Eliminate Beetles in a Finished Slab

Heating in a kiln to 130 degrees Fahrenheit will destroy the finish, but it's the only sure, safe way to kill the bugs. June 18, 2010

Wood Worms

White worms in reclaimed lumber intended for furniture. What to do? April 20, 2011

Mahogany Honeycombing Defect

Honeycombing that appears after planing is typically a drying defect — similar to end checking, but different. April 17, 2009

Heat Treating Wood for Overseas Shipment

The rules for heat-treating lumber for shipment overseas are impracticable because of the likely damage to both the lumber and the treating kiln. January 12, 2015

Lumber weight as a drying signpost

Calculating weight and moisture loss in a dehumidifcation kiln. July 24, 2001

Kiln dried: Better than air dried?

Why kiln-dried lumber is the best option for wood that will eventually 'live' indoors. 1998.

Whether to Air-Dry Before Kiln-Drying

In almost all cases, better quality is obtained by kiln-drying from green. May 27, 2006

Moisture Content for Furniture Making

Lumber in the kiln is ready when its moisture content is the same that it will see in service. August 21, 2006

Mold on Southern Pine

The wood doctor explains why Southern Pine supposedly dried to 18% moisture content would still support mold after being stacked inside a dried-in house under construction. January 25, 2013

You say pecan, I say hickory

Pecan lumber is usually sold as hickory. June 20, 2000

Difficulty with Drying Small Loads

Running a predryer with a quarter charge of green wood is tricky to manage and full of risks. April 24, 2014

Drying Holly

Holly wood is prized for its white color, but it stains easily during drying. October 1, 2010

Small Charges in the Drying Kiln

Running the kiln partially loaded involves some tweaks and compromises. August 8, 2008

Forced Air Circulation in a Solar Kiln

An example of a fan-and-plastic-sheeting setup that forces air through the lumber stack. May 14, 2006

Re-Drying A Few Wet Pieces to Speed Production

One way to dry loads of lumber more quickly is to separate out the few still-wet pieces for a second pass through the kiln. June 13, 2014

Slippery kiln-dried wood

What could make dried wood so slippery that it is difficult to machine? August 12, 2001

Drying Hickory with the Bark

Secrets of preserving the bark on Hickory during drying. April 18, 2010

"True honeycomb" defined

What is "true honeycomb" and what causes it? November 7, 2001

Cupping of resawn lumber

The two reasons wood cups when resawn. 1998.

Re-Sawing or Re-Wetting Partially Dried Wood

Either would be a mistake. January 14, 2009

Wood Doc's Video about Wood Moisture

Here's Dr. Gene Wengert's video presentation about wood moisture content and wood behavior. August 16, 2012

Adding Fans to a Dehumidifier Kiln

Is it worth it to exceed the design air circulation in a dehumidifier kiln? By the numbers, probably not. May 15, 2012

Drying Lumber in the Attic

It's hot and dry up there — maybe too dry. But for small amounts, attic drying is feasible, though tricky. December 1, 2005

Pink Stain in White Ash

Pink fungal staining is tough to bleach out, and may be allergenic. March 9, 2010

Lumber from a lake bottom??

Is it possible to dry logs which have spent 50 years underwater? January 31, 2001

Drying Submerged Logs Recovered from a Lake

A discussion of the technical and legal issues relating to recovered "sinker" logs. September 6, 2010

Cypress board and batten siding

It's better to kiln dry that cypress before siding your house with it than to let air-drying suffice. 1998.

Drying Very Large Oak Timbers

Big timbers should dry very slowly, and even then, the wood may be damaged. May 3, 2011

Drying 4" by 12" White Oak

Slow air-drying before kiln-drying will partially limit the cracking of large pieces of White Oak.

Preventing Sticker Stain

Stickers should be kiln-dry, and quickly pre-drying boards on end can help. August 31, 2005

Drying to ISPM 15 Specs

Wood for foreign-bound pallets and crating needs to be heat-treated according to International Standards for Phytosanitary Measures (ISPM) criteria. There's a strict standard and a verification requirement, so it's not a casual undertaking. August 29, 2006

Drying Cherry with Complex Grain

Tips on how to dry some pieces of highly figured Cherry wood. April 27, 2007

Drying Time for Black Walnut

Dry slowly to prevent checking, and test with a moisture meter. February 26, 2005

Whether to Run a Dehumidifier in a Solar Kiln

Solar kilns usually run too hot to be suitable for a dehumidification approach. Correct venting is the key. January 17, 2011

Dry Kiln Operator's Manual

A publication of the Forest Products Laboratory. August 22, 2003

Test for Honeycomb

A method for testing dried lumber to detect honeycomb, with advice on how to prevent the checking that leads to honeycomb. June 13, 2014

Drying Softwoods

If the product is structural lumber rather than appearance-grade wood, just dry the stuff as fast as your equipment can. January 27, 2007

Using a moisture meter

How and where to use a moisture meter. November 14, 2001

Techniques for drying wooden bowls

Advice on how to dry large, turned vessels. 1998.

Drying red oak

Is air drying, prior to kiln drying, a good idea? March 20, 2001

Lumber drying options and efficiencies

The Wood Doctor's favorite references for making decisions among lumber-drying options. 1998.

Wet Pockets in Infected Wood

Bacterial infections cause wet pockets to remain in kiln-dried wood. Bad smells and other characteristic symptoms are described here. July 28, 2006

Interior kiln coating

Products to use as a sealer over OSB. October 9, 2002

Drying Rates of Different Wood Varieties

Drying rates are complicated because they depend on wood density as well as other factors. October 19, 2013

Controls and Venting for a Dehumidifier Kiln

Advice on controlling the conditions in a dehumidifier kiln. August 1, 2011

Dark Core in Soft Maple

A kiln operator finds that his maple boards develop a light surface and dark core. Others weigh in with thoughts and advice. August 31, 2005

Kiln drying Mexican oak

Mexican oak can be dried using the same schedules as those used by processors in the United States. 1998.

Solar Kiln Fans Question

An airflow management problem in a solar kiln. April 15, 2012

Mold on Green Lumber

Quick drying should contain most mold problems encountered on freshly-sawn green lumber arriving at the kiln. June 13, 2014

Controlling color in air-dried alder

Ideas for achieving color uniformity when air-drying alder. July 26, 2000

Verifying moisture meters' accuracy

A discussion of ways to verify the accuracy of moisture meters. Includes info on calibration. June 21, 2000

Lumber Degrade Above or Below FSP

Is wood subject to degrade and defects above or below FSP?

Acid, Aluminum, Oak, and Kiln Durability

The acids in Oak can attack aluminum kiln components. Here's advice on managing the problem. July 15, 2012

Spots revealed in dry, planed lumber

Dr. Gene attempts to find the causes of discolored spots on dried lumber, revealed only when the stock has been planed. 1998.

Drying green tongue-and-groove pine

Success in drying green, already-machined lumber has much to do with the species. 1998.

Twisting lumber

What causes lumber to twist in a dehumidification kiln? March 20, 2001

Conditioning lumber -- The final step in drying

Why conditioning is the last but crucial step in the drying process. December 12, 2000

Drying hickory lumber

Avoiding sticker stain and bugs in hickory lumber. December 12, 2000

Checking of Dry Lumber

Checking occurs when the wood is very wet. Checking that appears in lumber purchased as kiln-dried is a defect. December 8, 2012

Temperature maximums for dehumidification units

and that's plenty. 1998.

Nyle L150 dehumidification system

A discussion about whether a Nyle L150 dehumidification system is salvagable. March 6, 2000

Maple processing basics

The fundamentals of milling and drying maple. August 10, 2000

Moisture Meters: Correcting for Temperature

Understanding the effect of cold temperatures and freezing on moisture meter readings. October 1, 2009

Optimizing Airflow in a Solar Kiln

Ideal airflow in a kiln varies by wood species. Here are some rules of thumb. December 31, 2012

Drying Rates and Settings in a Dehumidifier Kiln

How to understand your dehumidifier kiln's capacity and drying rate. December 6, 2012

Controlling Bugs in Finished Furniture

Fumigation or spraying are ineffective and have drawbacks. Instead, here's a tip for heat-treating furniture. April 24, 2013

Sticker stain solutions

A look at potential causes and solutions for sticker stain. July 11, 2000

Drying Logs for Cabin Construction

Advice on drying logs for cabin building, including how long to expect air drying to take and how hot to heat logs to set the pitch. October 19, 2014

Force Drying Pecan Slabs

Don't try high heat on Pecan — it can split badly even when slowly air-dried. February 3, 2011

Causes for warpage after planing

Why boards may warp after surfacing. January 16, 2001

Solar and Dehumidifier Kiln in Winter

Thoughts on how to improve the poor performance of a solar drying kiln during winter. December 31, 2012

After-the-kiln powderpost beetle infestation

Who's responsible for a powderpost beetle infestation, two years after the wood was kiln-dried? June 27, 2000

Mixing Frozen and Green Lumber in a Kiln

It's best to separate the loads. Here's some insight into why. December 9, 2010

Drying Mixed Thicknesses of Lumber

Tips on how to air-dry and kiln-dry lumber of different sawn thicknesses. October 1, 2009

Setting the pitch

The why and how of setting the pitch in heart pine. October 15, 2001

Cures for sticker stain

Drying lumber can suffer from sticker stain for a variety of reasons. June 20, 2000

Boiling Wood

Boiling wood before drying has various effects on the outcome. May 23, 2011

Control Issues in a Dehumidifier Kiln

If you run the kiln too hot, a safety cutoff may shut down your compressor, interfering with the drying process. April 27, 2007

Testing for Case-Hardening and Drying Stress

Tips on detecting drying stress. October 29, 2008

Primary processing profit parameters

Some goal guidelines for profitability in kiln-drying operations. July 26, 2000

Sticker Stain in Hickory

Sticker stain is a warm-weather phenomenon. Here's advice about a suitable schedule for drying Hickory. May 27, 2014

Time and Temperature to Kill Bugs

Advice on heat treating for pest control. October 17, 2012

Hackberry sawing and drying

How to saw and dry hackberry to avoid chemical staining. March 7, 2000

Bug Control: Pesticide, or a Salamander Heater?

Warnings: Pesticides will likely not penetrate lumber and kill a particular pest, and heating wood with fuel combustion exhaust can cause discoloration. January 28, 2014

Maple Stain in a Kiln Load

Some explanation about why soft maple would stain in the kiln when hard maple in the same load did not. June 13, 2014

Preventing Drying Damage to Oak

Advice on controlling the drying conditions for Oak. December 6, 2009

Pin and pinless moisture meters

The pros and cons of pinless and pin-type moisture meters. March 20, 2001

Home dehumidifier for drying lumber

Can a home dehumidifier be used to kiln dry lumber? January 31, 2001

Kiln venting

Are vents needed in a condenser kiln? March 20, 2001

Wood Moisture Content and Equalization

Understanding how to evaluate wood moisture content when conditions have created a moisture gradient within the wood. April 11, 2008

Good Steaming Conditions for Walnut

Getting lots of hot, wet steam is the trick — but it's not easy to achieve. October 1, 2010

Kiln Baffle Material

Canvas or carpet works well for directing air through the wood stack in a kiln. January 14, 2009

Drying Massive Slabs

Air-drying and kiln-drying 12/4 or 16/4 hardwood slabs is slow and difficult, and the results can be mediocre. February 29, 2012

Heat Treating Logs On Site

Doubts on the feasibility of drying Southern Yellow Pine logs using temporary means at a building site. January 25, 2010

A good, cheap end sealant?

A discussion of the pros and cons of various sealants used on ends of boards in primary lumber processing. April 22, 2000

Determining Wood EMC -- (Equilibrium Moisture Content)

How to calculate and establish EMC. From the Forest Products Laboratory. February 16, 2004

DH kiln preferences

A look at dehumidification kiln construction, and manufacturers of DH units. July 26, 2000

Variable Speed Fan Efficiency

People do drive their kiln fans above rated capacity sometimes, but it's an inefficient use of energy. June 13, 2014

Does Rougher Wood Dry Faster?

Surface conditions do not control the overall rate of drying. July 28, 2008

Estimating BF yields

Some formulas for calculating board foot yields from rough logs. March 1, 2000

Drying pine for a trestle table

A brief look at the basics of drying freshly milled, 3-inch-thick pine. 1998.

Shrinkage allowances for red oak

Estimating radial and tangential shrinkage when drying red oak to 12 to 14 percent MC. 1998.

Yellow Pine Pitch

Heating yellow pine will set the pitch. December 15, 2005

Kiln-drying energy: Too cheap to save?

Sleep lost over the most efficient way to insulate a wood kiln will yield only lost sleep, not big savings. 1998.

Using A Wood-Fired Boiler to Heat a Kiln

BTU output and controls are the important concerns. August 26, 2008

Darkening Problem when Heating Ash to Kill Borers

Dry the wood first, then heat it, says the Wood Doctor. July 29, 2011

Salvaging lumber from submerged wood

The best chance for salvaging lumber from submerged wood lies in cutting it quickly, and drying it slowly. 1998.

Warping after planing

Causes for the warping of boards after they are planed flat. June 13, 2001

Characteristics of butt log lumber

Denser, darker wood than the rest of that from the same laod may be from butt logs. 1998.

Drying Horticultural Maple

Specialty Maples used in landscaping dry like other Maple, but the wood tends to be twisty. June 16, 2014

Kiln-Drying Associations -- Contact Info

Here's address, website, and contact information on several regional kiln-drying industry associations. March 30, 2008

A facility for storing kilned lumber

What's a good facility for storing kilned lumber without raising its moisture content? May 6, 2000

Pause button on kiln?

Is lumber adversely affected if drying is suspended late in the kiln schedule? August 1, 2000

Moisture transfer in humid climes

Do tropical and sub-tropical species re-absorb moisture when left in their humid, native lands? September 6, 2000

Thinner Sticks in the Lumber Drying Pile

Reducing the thickness of spacer sticks in the lumber stack could reduce the drying effectiveness of the system and create quality issues. October 19, 2014

Tips for drying butternut burls

Butternut burls are dried much like regular lumber. Also, a source for further information on drying burls. 1998.

Ratios: Relative humidity to moisture content

Common conversions and instruments used in measuring wood moisture content. October 31, 2000

Stains on wood

remove. June 27, 2000

Sinker logs: Cutting, use and grading

A quick review of the cutting, use, and grading of lumber from sinker logs. June 20, 2000

Drying small pieces in microwave

You can dry lumber in a microwave oven, under certain conditions. 1998.

Setting Pitch with a Solar Kiln

If the kiln doesn't get hot enough from sunshine alone, try some supplemental electric heat. July 10, 2007

"Depression" explained

How to determine relative humidity with two types of temperature readings. June 20, 2000

Solar Kilns in Humid Climates

Solar kilns work well even in humid climates, because heating damp air lowers its relative humidity. April 30, 2006

Stained oak from supplier

There are solutions for stained, milled, not-yet-dried oak lumber, but first , one must determine the cause of the staining. 1998.

Gross tally vs. net tally

The difference between "gross" and "net" tallies in lumber processing is explained. July 18, 2000

Case hardening in white oak

Is case hardening common in white oak, and should it be accepted? July 18, 2000

Sticker specs and spacing

Basic info on the size and proper spacing of stickers when drying lumber. June 21, 2000

MC in imported mahogany furniture

Moisture contents higher than eight percent are suspect, and suppliers must be notified. 1998.

Honeycomb Caused by Stickers?

Do stickers cause honeycomb? Well, it could happen. December 6, 2011

Pricing custom kiln drying services

How to determine what to charge when kiln drying lumber for others. January 3, 2001

Drying Beech

Beech is a tricky wood to dry: too fast and it checks, too slow and it stains. August 21, 2006

Remotely Readable Moisture Probes for Wood Drying

Probes you can read without going inside the drying kiln are not a lot of help with the most problematic drying-related defects. March 16, 2015

Drying Loads with Mixed Moisture Content

It's a balancing act — you have to watch out for the drier wood causing the wetter wood to dry too fast and check. October 4, 2011

Correcting case hardening

Correcting case hardening in processed lumber. July 11, 2000

Temperature Versus Relative Humidity

Links to curves that plot the relationship. February 26, 2005

Time and Temperature Curve to Kill Bugs

Here's a little basic info on bug killing with heat in thicker pieces of wood in the kiln. June 22, 2012

Casehardening explained

The Wood Doctor describes casehardening, its causes, and cure. July 18, 2000

Night-time Reconditioning in Solar Kiln Operation

The nightly humidity increase in a solar kiln is not harmful to the drying lumber, but helps to relieve stress. December 31, 2013

110-Volt Fans for Use in Kilns

Advice on finding fans that will perform in a drying kiln. July 3, 2008

Dry Kiln Schedules for Commercial Woods - Temperate and Tropical

Authoritative kiln schedules for 500 different domestic and foreign wood species. August 2, 2008

Wet bulb, dry bulb

An explanation of the terms "wet bulb" and "dry bulb" in reference to temperature measurement, and their particular usefulness. March 6, 2000

Solar or dehumidification kiln?

A discussion of the merits of two types of kilns for lumber processing. March 12, 2000

Stacking a Kiln: Tight or Spaced Out?

Lumber in a drying kiln should be close packed edge to edge. December 23, 2014

Dark liquid from walnut: Toxic?

The Wood Doctor says: Stay away from this stuff! 1998.

Mixed Drying Loads

Mixing wood of different moisture contents in the same kiln load causes big problems, but mixing different lumber species at the same moisture content can be okay. May 15, 2012

Effects of humidity swing

How does a swing in humidity affect drying time and MC gradient? February 28, 2001

Drying Hardwood Lumber

A publication from the Forest Products Laboratory. August 22, 2003

Kiln Charge Cooling

Cooling lumber arter drying is not a critical step. June 13, 2014

Drying wood for drums

Avoiding checks, splits and cracks when drying lumber rounds for drum bodies. September 6, 2000

Kiln Drying Gum

Sap Gum and Red Gum should be dried separately using different schedules. January 2, 2012

Drying Oak Lumber -- Ordering Information

Where to send your check or money order to receive a copy of this useful text. May 10, 2001

Heat considerations in solar kilns

Solar kilns get hot enough to handle some aspects of lumber drying, but not all of them. March 6, 2000

Solar kiln construction - and more

are answered.

Understanding the Drying of Wood

Here's a handy resource on the hows and whys of drying lumber. June 21, 2007

Drying hard maple for whiteness

Permissible extremes for dehumification drying of maple, to accentuate whiteness. 1998.

Drying South American hardwoods

Dr. Gene Wengert provides a resource for information on drying tropical hardwoods. 1998.

Quality Drying of Softwood Lumber

A publication from the Forest Service in PDF format. August 22, 2003

Quality Drying of Hardwood Lumber

A publication from the Forest Service in PDF format. August 22, 2003

Preventing brown stain on pine

Warm weather is the culprit; keeping still-to-be-processed logs cools is the solution. 1998.

Weighting lumber stacks

How much weight is necessary for stacked lumber, ready to be air-dried? June 5, 2001

Drying Eastern Hardwood Lumber

Authoritative how-to on cost-effective kiln-drying of hardwood lumber. November 24, 2007

Preventing discoloration in rubber wood

The two causes of discoloration in rubber wood, and how to avoid them. August 10, 2000

Trouble drying 8/4 oak

Drying 8/4 oak too rapidly will damage the wood. February 29, 2000

EMC/RH ratios

Here's a listing of equilibrium moisture content to relative humidity ratios. July 11, 2000

Oak cupping and warping

When during drying does oak lumber stop cupping and warping? July 4, 2000

Drying hackberry

Drying hackberry is easy, provided you move quickly. June 5, 2001

Solar Drying Basics (PDF)

Illustrated article from the West Virginia University Extension Serivce on solar drying and kilns, in PDF format. June 19, 2003

Drying red and white oak -- together?

Can red and white oak be kiln-dried together? March 20, 2001

DH kiln operation

A resource for DH kiln operation. 1998.

What can be dried with black walnut?

How to determine what species are compatible for drying with black walnut. June 20, 2000

Solar Kiln Glass

Are different types of glass more or less suitable for solar kilns? May 11, 2005

Kiln-drying eucalyptus

Recommended temperatures for drying this native Australian species. 1998.

A Checklist for Drying -- Small Amounts of Lumber

A publication from the Forest Service in PDF format. August 22, 2003

Timetable for final processing of walnut

Stock in cants form should be processed in a timely manner. March 26, 2000

Dry Kiln Schedules -- for Commercial Woods

A publication from the Forest Service in PDF format. August 22, 2003

Kiln fan settings

Guidelines for setting thermostatically controlled fans in lumber kilns. March 3, 2000

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