Drying 4" by 12" White Oak
Slow air-drying before kiln-drying will partially limit the cracking of large pieces of White Oak.
Question
I’m going to be having some green 4" x 12" x 16' white oak dried in a kiln and was just wondering if you experienced wood drying guys had any information that you could pass on to me about drying wood this thick. We are using these big pieces of wood for upscale farm wagons we are building and need the wood to be dried because I am going to be spraying an exterior finish on all wood parts of the wagon before it is put together. So, I’m trying to avoid possible finish problems by the wood not being dried properly. Thank you in advance for any advice.
Forum Responses
(Sawing and Drying Forum)
From Gene Wengert, forum technical advisor:
You need to air dry this wood very slowly for two years before it sees the inside of a kiln. Even then, it will have large cracks along its length. For an outside wagon, you need to achieve 12-15% MC to assure some degree of stability. If the design allows, you would be much better off to cut 4/4 lumber, dry it and then glue it back together in the same order it was sawn into the larger beam.
From contributor A:
Your only other choice is to have a vacuum kiln dry it. They can do it if you can find one for the length that you have. Large chunks take a long time to dry. Most wagons were built with green or air dried lumber and dried in place.
From Gene Wengert, forum technical advisor:
My experience with white oak in vacuum kilns is that the lack of porosity of the wood (that is why white oak is used for wine and whiskey barrels) prevents drying of such large pieces of white oak (except for chestnut white oak which has more porosity).
From contributor S:
A big outfit near me specializes in thick oak and they use a pre-dyer for eight months to a year before the kiln when they are drying any white oak over 6/4. The pre dryer uses waste heat from the kiln to keep the temperature warm (about 90 degrees) and the humidity also somewhat high. Some areas of the pre-dryer seem warmer than others and the supervisor there is very careful where he places the different thicknesses and species. As far as spraying a finish, perhaps an oil based stain type finish will solve your problem.
