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Every month we order about 1000 bdft of 5/4 soft maple , this month my sales man said the reason the delivery is late is that the maple is still in the kiln . So as soon as it comes out it will be delivered . My question is , is the material ok to use right after it leaves the kiln ? Just curious . Maybe we used it like that before and just never knew , we never had any problems don't want to start
I believe that if they have properly completed their drying process, the sooner you get it, the better. I have been told by several suppliers, read here on Woodweb, and it seems my moisture meter confirms this, that the dried lumber can begin adjusting back to a higher moisture content based on the environment where it is stored. My being in the southeast, that means a lot of dried lumber is stored under sheds and warehouses, and eventually shops where the RH may cause the moisture content to rise a few points. So personally I prefer to get it from the kiln asap. Not something I even consider on a weekly basis, that just would be my preference if I have a choice.
If properly dried, lumber can be used within several days after leaving the kiln. As mentioned, kiln drying does not guarantee that the wood is at the correct MC or that subsequent storage has changed the MC. So, check the MC yourself with a moisture meter that costs over $200 and is made in USA.
Lots of time, the final step in the kiln is a high humidity treatment to relieve the stresses. So lumber that leaves the kiln will have a high surface MC that needs to be evaporated. For that reason, the lumber is not u stacked right when it leaves the kiln, but is allowed to "rest." Sometimes this resting for a few days is called "cooling." Then the lumber is u stacked, and is ready for use. Checking the MC with a pin-type MC meter will let you know if the surface MC is too high or not.
Agree with the Doc ,regardless of the exact moisture content when it leaves the kiln the lumber reaches a new and usually different RH factor as it adjusts to its new climate or en route . I would let the lumber climitize to your shop for a few days maybe.
I agree with D Brown, but unless you check the MC, you will not know if the equalization will take several days or will take longer. It depends how far off the MC is from what you want...obviously. If it is a tight bundle, it may take months, so open the bundle and spread the lumber out. thicker takes longer too. So, use the moisture meter to find out when you are done.
I have a Wagner pinless meter , but I do not trust it . When I tested against my friends meter with pins , there was a pretty big difference . How can I verify that my meter is correct ?
On lumber under 15% MC, the two meters should be within 1% MC if used correctly.
The pinless meter is very sensitive to density; the most common reason for poor readings is that the incorrect density for the wood being tested has been entered. Note that this meter reads an average.
The pin meter reads at a spot--the tip of the needles with insulated needles or the wettest spot for uninsulated needles, but it is just a spot. Temperature corrections are needed.
So, comparing a Wagner to a pin may not always give the same values because one is the MC at a spot and the other is an average. So, the two meters may disagree if there is a moisture gradient within the wood, if the density is not "normal" for the species, or the wood is not between 60 to 80 degrees F.
Wagner used to sell a calibration plate for their meters that read a specified value (like 10.0% MC, depending on the model). Delmhorst used to sell a calibration resistor (20 megohms, I believe, that should read 20.0% MC). The Delmhorst resistor is now built in to their meters, so calibration is automatic. But, it did not matter whose made the meter; 20 megohms should read 20% MC for all.
I have seen static electricity fool a meter. I have seen temporary (several hours) condensation on a cold meter brought into a humid location goof things up. Weak batteries are also an issue.
Was your friend's meter made in USA? If not, it is common to find non-USA meters with faulty calibrations.
If you have a "Made in USA" meter, you can send it back to the factory for calibration, cleaning and checking. If it is critical, at least one company will send you a loaner while yours is in transit and being fixed.
I compared the three most common meters (Delmhorst, Lignomat and Wagner) on kiln dried lumber at room temperature with no MC gradient. You can see the results in the Appendix of DRYING HARDWOOD LUMBER, page 130. This book is in the Archives here at WoodWeb or on line.
Even at the same moisture content my