|
|
Whether to Air-Dry Before Kiln-Drying
Question
Forum Responses
From Gene Wengert, forum technical advisor: How many BF do you want to dry per year? How much kiln capacity do you have? This will tell you how long each kiln run will be. You can then look at each species and determine if you need to AD or can go green. If you have plenty of kiln capacity, then green is the best way to go. From contributor S: When you speak of "dense timbers," what size timbers are you attempting to dry? From contributor N: We dry subtropical hardwoods in Australia. All of our stock is air dried for at least 3 months. Drying dense timber from green has its problems, mainly the moisture variation at the end of drying. With air drying, you get a more consistent result. Our product is mainly floorboards, which must be + or - 1% of target mc – a very hard task when drying from green. I have found that the density variation in our subtropical hardwoods even in the same specie can be large and can cause a lot of problems when drying from green. From the original questioner: Many thanks. Our kilns are tight, leak free and well run. Capacity of 1,000m3. The capacity and schedules are really not too much a problem, but the current 3 month air-dry strategy has been adopted supposedly to reduce kilning reject rates - for no other reason. The species density we are talking about are averaging 650kg/m3 at 12-15%. Our lumber stacked outside mid-December is now averaging 28%MC. From Gene Wengert, forum technical advisor: In almost all cases, better quality is obtained by not air drying. The sun and rain cause quite a bit of quality loss. Almost all quality loss occurs or is set up to occur at high MCs. So that is where you control quality. Would you like to add information to this article? Interested in writing or submitting an article? Have a question about this article? Have you reviewed the related Knowledge Base areas below? 
|
