Good morning, :)
According to an instructive paper, "How PEG helps the hobbyist who works with wood" by H.L. Mitchell ( Link: http://owic.oregonstate.edu/sites/default/files/pubs/peg.pdf ), PEG 1000 has been successfully used for stabilizing walnut gunstock blanks and cross section tabletops. Professor Gene Wengert has also commented on using PEG 1000. ( Link: http://www.woodweb.com/knowledge_base/Using_PEG_for_dimensional_stability.html ).
Could PEG 1000 be used for stabilizing walnut slabs, such as a 30'' wide 9' long slab, rather than cross section ?
There are some concerns about this purpose:
(1) Cost
The cost of PEG 1000 is about 2000 USD per ton, if a walnut slab absorbs PEG 25-40% of its dry weight, assume 40%, the cost of PEG material per walnut slab will be 50-60 USD, which is acceptable.
(2) Soaking Schedule
According to H.L. Mitchell's paper, soaking in 50% 70F PEG solution, it takes 45 days to stabilize 2-3 inches thick walnut cross section tabletops. However, slabs must absorb PEG much less slowly than cross sections do.
I even don't know whether slabs will absorb enough PEG to a level of 25% of their dry weight...
(3) Insect killing
PEG treatment could be followed by air or kiln drying, if air drying, does soaking in room temperature PEG solution for weeks kill all PPB in the sapwood ?
according to "English Heritage Practical Building Conservation: Timber", water seasoning has been used for killing worm and reducing splits in 17th century.
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Although PEG treatment is costly and taking time, it brings solid benefits:
1) greatly improves wood dimensional stability, which can't be achieved only by drying.
2) speeds up drying time, meanwhile eliminates most drying degradation, thus reduces stock cost.
If this is going to be an on-going business, why not buy a vacuum kiln and skip the mess?
This walnut slab was stabilized with PEG.
(https://forestryforum.com/gallery/albums/userpics/10180/walnut_slab_reoil.jpg)
And now with LogRite's Allissa's legs, it is a beautiful coffee table.
(https://forestryforum.com/gallery/albums/userpics/10180/Alissa_legs~0.jpg)
Quote from: Den Socling on May 19, 2015, 10:12:18 PM
If this is going to be an on-going business, why not buy a vacuum kiln and skip the mess?
Hello Den Socling, I think vacuum kiln is necessary for drying thick slabs, what I meant was treating walnut slabs with PEG-1000 first, followed by vacuum drying, would provide additional benefits, the slabs would change dimension little or no in future use, which reduce the risk of split or warp caused by seasonal humidity change. :)
Quote from: beenthere on May 19, 2015, 10:42:27 PM
This walnut slab was stabilized with PEG.
(https://forestryforum.com/gallery/albums/userpics/10180/walnut_slab_reoil.jpg)
And now with LogRite's Allissa's legs, it is a beautiful coffee table.
(https://forestryforum.com/gallery/albums/userpics/10180/Alissa_legs~0.jpg)
Hello Beenthere, the crotch grain looks so charming :)
May I ask, how long did you soak this coffee tabletop in PEG solution ?
I don't know the soaking time, but likely the time H.L. Mitchell said. I bought it treated 50 years ago from the Crane Creek Co. (mentioned in the Bibliography of the Mitchell paper cited) that sold PEG to hobbyists. It was, I understood at the time, dried in a regular kiln.
Dough_baker, there is no need for the PEG if you are drying with a vac kiln. I'll send you some pictures of huge walnut slabs tomorrow.
Although PEG helps in drying, it also helps in stopping any movement AFTER drying. For a gunstock that has exposure to dry and damp atmospheres, this stability can be very important.
Note that a heated solution of PEG becomes diluted as the PEG moves into the wood and replaces the water, and the water moves out of the wood. So, you continually have to add more PEG to maintain the correct solution strength. Once done, you have left over solution that is weak and needs to have the water removed...you would not want to throw away the chemical. Is the $2000 cost including shipping? Is it only in one ton quantities?
PEG is applied to green wood that has not been dried. Therefore it does not have lyctid PPB, as they prefer drier wood. You comment about sapwood, however, indicates that you have a different insect in mind other than lyctid PPB. The insects cannot get into wood during treatment. Even if the eggs are laid between sawing and treating, the larva do not have time to mature. PEG is not an insecticide. The heat in drying will kill any existing insects and eggs.
baker, your name is written in Chinese in my contact list. How the dickens do I type that? :D So I didn't send pictures this morning. Patti found you this afternoon but I was busy. I'll send some pictures of walnut tomorrow. They are in the shop computer system and I'm not there.
Quote from: Den Socling on May 20, 2015, 08:17:23 PM
baker, your name is written in Chinese in my contact list. How the dickens do I type that? :D So I didn't send pictures this morning. Patti found you this afternoon but I was busy. I'll send some pictures of walnut tomorrow. They are in the shop computer system and I'm not there.
Good morning, Den Socling, sorry for the trouble you met :D
I am still trying to purchase a vacuum kiln and a WM-1000 bandsaw.
Quote from: beenthere on May 20, 2015, 12:20:11 AM
I don't know the soaking time, but likely the time H.L. Mitchell said. I bought it treated 50 years ago from the Crane Creek Co. (mentioned in the Bibliography of the Mitchell paper cited) that sold PEG to hobbyists. It was, I understood at the time, dried in a regular kiln.
50 years ago! It may be even not easy to saw such a slab at that time. Now, it is still in very sound condition.
Well, the vac kiln is easy. Our new model is cheap! I guy was here the other day and he wants to buy one. He said he was looking at a new 3/4 ton diesel power pickup. $65,000!. A kiln is less than two pickups, it makes money and it doesn't depreciate. I'll email you tomorrow. I have a truck coming then I'll get to you.
Quote from: GeneWengert-WoodDoc on May 20, 2015, 03:41:22 AM
Although PEG helps in drying, it also helps in stopping any movement AFTER drying. For a gunstock that has exposure to dry and damp atmospheres, this stability can be very important.
Note that a heated solution of PEG becomes diluted as the PEG moves into the wood and replaces the water, and the water moves out of the wood. So, you continually have to add more PEG to maintain the correct solution strength. Once done, you have left over solution that is weak and needs to have the water removed...you would not want to throw away the chemical. Is the $2000 cost including shipping? Is it only in one ton quantities?
PEG is applied to green wood that has not been dried. Therefore it does not have lyctid PPB, as they prefer drier wood. You comment about sapwood, however, indicates that you have a different insect in mind other than lyctid PPB. The insects cannot get into wood during treatment. Even if the eggs are laid between sawing and treating, the larva do not have time to mature. PEG is not an insecticide. The heat in drying will kill any existing insects and eggs.
Good morning, Prof. Gene Wengert,
2000 USD per ton is the lowest wholesale I could find on internet, with 1 ton MOQ. If I buy 500g packaging PEG 1000, the unit price would be more than 8000 USD per ton.
Prof. Gene Wengert, if lyctid PPB and other insects could be killed in an oxygen poor environment, for example in PEG solution, a 60-day PEG treatment may kill all of them?
You could also use Pentacryl to stabilize the wood. This guy uses Pentacryl for his slabs
http://www.logs-to-lumber.com/