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How long to heat to sterilize wood8/16
Still trying to heat this wood. I found an old thread that said heat the interior of wood to 130 degrees for 1/2 hour. Can some one give me an educated guess on how long it will take to get a 6x6x16 foot stack of 1 inch boards stacked with 1 inch spacers to an internal temperature of 130 degrees? I am hoping to get the temperature to 150. I have a squirrel cage from an old furnace shooting air under the stack and the duct sucking air in from the top of the enclosure. the stack is about 1 foot off of the ground. So I guess the question should be how long at 150 degrees? And what if I only achieve say 140 degrees?
You can buy a meat thermometer with a cable between probe and readout from Kitchen Bed and Bath, or even Target for under $20.
Drill a hole into the middle of one of your thickest boards as far into the middle of the stack, then you can watch it slowly rise to your target temp from outside of your cooker.
I also use another regular one to monitor the air in the chamber.
The time depends on the moisture content of the wood. With dry 4/4 at 150 F air temperature of the air actually blowing through the stack, it can take 8 hours or longer.
With 140 F, no less than three times longer.
The desired temperature in the wood for every piece and at every spot within the wood is 133 F,
Thanks for the advice. I believe the wood is finally sterilized. I kept it over 150 for 12 hours. My meat thermometer said 139 in one of my board. I had 2 torpedo heaters shooting the heat in through home made double walled pipes with insulation between the pipes. Also a blower from an old furnace circulating the air. A 30 dollar thermostat worked well. Do 2 inch boards take 2x as long to heat treat compared to 1 inch boards?
Next I plan to edge, plane, and polyurethane the boards. I will only take out what I can get polyurethaned in one day because I don.t want to take a chance at re-infestation I assume I wont have to worry about re-infestation once they are polyurethaned, but how long can they be outside ( under barn) before they will pick up too much moisture to be installed as an interior ceiling?
What species of wood?
What insect did you have in the wood?
Was the wood kiln dried and at what maximum temperature?
What is the wood's moisture content now?
Is the house heated in the wintertime? How cold does it get outside? What sort of edge joints will you use between pieces of wood? Will shrinking in the winter and swelling in the summer affect the appearance?
Usually we would sand the wood prior to using poly. It is correct that a thick enough coat of poly on all surfaces prevents the insects from laying eggs on or in the wood.
Species is yellow pine.
Not sure what the small boring insects were.
The boards were air dried for years (Hence the bug problem) and then they were dehumidified in the the enclosure with fans and a house dehumidifier prior to being heated for the bugs. From what I have read online the torpedo heaters should have added moisture to the boards, but if my moisture meter is correct they are too dry now. most register 0% and a few up to 5% They were ranging from 5-10 % prior to the heat treatment. I have the humidifier still running but set on 50% since that is what I think is supposed to be a good moisture level in a house. I am afraid if I don't run it some, moisture will gradually seep in to the enclosure.
I have a shaper So I could do T&G,but was thinking of just edging and then planing one side. I am planning on nailing them from the top over 6x8 beams so the fasteners won't be seen. The house will be heated in the winter and cooled in the summer. I live close to Atlanta GA So winters are fairly mild usually. Usually above freezing during the day.
There is only one insect that gets into dry pine and that is the old house borer and it is seldom seen. So, you can be confident that you will not have any insect issues unless you store this wood adjacent to infected wood.
Your moisture meter is not working well, as it is virtually impossible to get under 3.5% MC with the conditions you had. The pin meter cannot register under 6.5% MC and the painless under 4.5% MC. On the other hand, even 5% MC is too dry for your ceiling, as in the summer weather, the wood will or would try to expand as much as 1-1/2% in size in the summer from th dry MC that you have now. Of course, the wood will dry out to 6% MC in the wintertime, so some shrinkage will occur. This normal movement must be considered when deciding the style (like tongue and groove) and the installation procedures...for example, the tongue must be long enough and only one edge is nailed so that the wood is free to expand and contract perhaps as much as 1% annually.
Note that very low MC also means a lot of chipping when machining, so 55% RH or even 58% RH is good now.
Are you close to Athens? I could let you borrow my meter.
I have lots of infected wood but will try to keep it separate. I have an old sawmill and have cut wood for the last 15 years and still have most of stacked in barns. Not a good plan, for storage I now realize. I just saw milled any trees that I needed to take down for a fence, house, or barn or if the needles started to turn brown. I cut down an oak tree awhile back. It was alive when I cut it down. It sat at the sawmill for only a few weeks and when I cut it it had some boring bugs. I sprayed it with timbor as soon as I cut it. I wish I had done that to all the lumber I cut years ago. Anyway I sure have bug problems
I will look up the old house borer and read about it. So when you say the only bug that will get in dry pine do you mean air dried or kiln dried?
I have two moisture meters that I just recently purchased. they are Dr meter MD912 with pins and Dr. meter MD918 with out pins. The problem with their operation could be with the operator. I will take a good look at the directions again
I just set the humidifier at 55%
Thanks for the advice
Just looked up old house borer. I think I have a few of those, but mostly I have much smaller holes (only a 16th of an inch or less). Will they leave any way once the wood is 7% moisture or less?
We do have a beetle that makes small holes, 1/16”, often with a dark region inside the hole, called the ambrosia beetle. It is common. It is not able to live in wood under 20% MC.