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Does vacuum drying kiln work well on white oak ?

Started by Dough_baker, February 23, 2015, 09:13:41 AM

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Dough_baker

Morning,  :)

Make some study on vacuum drying, it must be the most suitable drying method for thick lumber or slab, maybe the only disadvantage is initial expense.

On Dennis Socling's website, it is said that "some of the domestic species that our kilns have dried:  Red oak, cherry, hickory, ash, American beech, maple, box elder, black walnut, butternut, elm, pine, hemlock and holly. We are finalizing schedules for white oak" (http://vacdry.com/index.php/projects/drying-slabs)



So, that is, vacuum kiln works on white oak.

Is WO hard to dry by vacuum kiln?
And who knows how much a small vacuum kiln costs?

Best Regards,
Baker

Den Socling

For years I used "conventional" wisdom when drying WO in our vacuum kilns. Results were OK for thin lumber but not heavy. Then last fall I tried a different approach and dried 10/4 in 9 days and you couldn't find a surface check. I need to get back to that schedule development when time allows.

Kilns start at $95K but you get more bang-to-your-buck with bigger kilns.

GeneWengert-WoodDoc

As you might already know, white oak is used for whiskey and wine barrels today and was used even for water barrels in the past.  Most white oak has pores (or vessels) that are plugged with chemicals (technical name is occluded), so it is very difficult for liquids to move through the white oak wood (not sapwood, but heartwood).   (The key is the word "most" as some white oaks, such as chestnut oak, which is in the white oak family, and a few other species are exceptions, and would not be used for liquid barrels.)  Other species, such as Osage orange, also have occlusions.  When we build a barrel for liquids, called tight cooperage, the final test is that some water is put into the barrel and then the barrel is pressurized to a given, precise value.  Then, after several hours, the pressure is looked at and if the pressure has not dropped, the barrel passes.  A leaky barrel can be because sapwood was included, because the joint between the staves or the head joint to the staves, or the head itself are not tight enough, or because chestnut oak was used.

When vacuum drying, without being fancy, the water needs to flow out of the wood quickly, but such flowing is difficult in the species that are occluded.  So, what we would like to have happen, and Den has indeed made it happen, is that the liquid water in the wood is converted to vapor and then the vapor is able to work its way out of the wood much easier than liquid can and is encouraged to move by the schedule used.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Dough_baker

Quote from: GeneWengert-WoodDoc on February 23, 2015, 10:37:03 PM
As you might already know, white oak is used for whiskey and wine barrels today and was used even for water barrels in the past.  Most white oak has pores (or vessels) that are plugged with chemicals (technical name is occluded), so it is very difficult for liquids to move through the white oak wood (not sapwood, but heartwood).   (The key is the word "most" as some white oaks, such as chestnut oak, which is in the white oak family, and a few other species are exceptions, and would not be used for liquid barrels.)  Other species, such as Osage orange, also has occlusions.  When we build a barrel for liquids, called tight cooperage, the final test is that some water is put into the barrel and then the barrel is pressurized to a given, precise value,  after several hours, the pressure is looked at and if the pressure has not dropped, the barrel passes.  A leaky barrel can be because sapwood was included, because the joint between the staves or the head joint to the staves, or the head itself are not tight enough, or because chestnut oak was used.

When vacuum drying, without being fancy, the water needs to flow out of the wood quickly, but such flowing is difficult in the species that are occluded.  So, what we would like to have happen, and Den has indeed made it happen, is that the liquid water in the wood is converted to vapor and then the vapor is able to work its way out of the wood much easier than liquid can and is encouraged to move by the schedule used.

Hello Dr Wengert, I have contacted Den Socling for more details about his kiln. Appreciate your informed replies  all the time.  :P

scsmith42

Very insightful response Gene - thanks for sharing.
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

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