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David Mealey
04-19-2017, 9:16 PM
In a recent previous post I asked about optimal humidity in the kiln and was told that controlling the kiln temperature is more important. Does anyone have a reference to optimal temperatures and/or schedules for different sizes, thickness, or species of the wood being dried. I think I"m case hardening my wood by pumping to much heat to fast.

Thanks,

David M.
Milwaukie Hardwoods, LLC

Ralph Boumenot
04-20-2017, 4:44 AM
check with the US Forestry Service

Jeff Heath
04-20-2017, 5:50 PM
From what I've learned, every kiln is different. The correct answer is "it depends" on what kiln you're using. Different style kilns dry wood in different ways. You should be able to get drying schedules from the manufacturer of your kiln.

There's quite a bit of this discussed over at the Forestry Forum in the wood drying sub-forum. Dr. Gene Wengert is the moderator over there, and he's....well......the man.

Scott T Smith
04-21-2017, 6:12 PM
David, there are published kiln schedules by the Forestry Products Lab available for free. Most of these are for conventional (steam) high temperature kilns, but there are also some available for lower temperature dehumidification kilns. Google the USDA Kiln Operators Handbood for some information, or better yet purchase a copy of "Drying Hardwood Lumber" by Gene Wengert, et al.

Additionally, kiln manufacturers such as Nyle publish schedules that they recommend for their kilns, as do vacuum kiln makers.

Typically you manage both the temperature and relative humidity in a kiln, adjusting both settings as the wood dries (Usually you increase the temp and decrease the RH% and the MC% is reduced). 8/4 schedules typically require 60% more time than 4/4 schedules.

There can be a very steep and expensive learning curve to properly operating a kiln. As Jeff stated above, the Forestry Forum is a great place to go for more info.

Scott