questions for Mr Carnell

[bugeye]

Hi,
In rebuilding my boat I have been following your suggestions of using anti freeze as a preservative/stabilizer. I've been wondering how the glycol works. When the surface of the wood dries, is there anything left behind. I know that with timbor solutions, the water dries but leaves behind the salts. You've also mentioned that glycol is effective as a stabilizer because it is so slow to evaporate and it attracts moisture. Does it rely on this property to keep the wood poisonous, or can the wood totally dry out and still be poisonous. I hope that I'm stating my question clearly, I'm not sure. meanwhile I'll keep using it. I just finished laying the deck. In every hole that I drilled for spikes, I drooled a bit of antifreeze, figuring that it was a good opportunity to get the poison 3" down into the deckbeams, and I found that it makes the spikes alot easier to drive. I have faith that the glycol will dissipate into the surrounding wood, and cease to act as a lubricant. Thanks for your help

[Dave Carnell]

Bugeye, the glycol is absorbed into the wood much as water is, but it is its inherent toxicity to organisms from staphylococcus bacteria to humans (by ingestion, not skin contact) that kills and prevents rot. It is my fond hope that someone will extend my research in a serious fashion, but there is no commercial incentive for getting EPA registration, as it would have no exclusivity. U. S. Borax is happy to have others piggyback on their EPA registration of sodium octaborate, as they are the only producers of the material. I am 81 and have no real laboratory facilities.

That said let me summarize my anecdotal evidence. I used antifreeze to stabilize a roughly 15" D. by 2" thick green hickory slab from cracking as it dried. An untreated control alongside it fell into pieces and a thick white fungus growth appeared while the treated slab stayed sound with no fungus growth. An untreated rope mat at my back door rotted to mush after two years. The treated replacement is still sound after over eight years though continually exposed to rain. A white pine frame in a utility rowboat rotted badly; cutting away the badly rotted area and treating the rest with antifreeze stopped further rot even though the boat still freqyently has rain water in the bilge.

Others argue that glycol is water-soluble and will be leached out. The solubility is undeniable, but it is also so strongly attracted to wood that a few drops swell chair rungs tight in minutes. No one knows how much has to be there to kill rot organisms-probably very little; or how much is unextracted even after considerable exposure to water.

It does dry on the surface so that gluing and finishing are unaffected. How I wish some academic institution would make a thorough scientific study. What a subject for a thesis project! I rest my case.

[bugeye]

Thanks Dave!

[HS]

I remember seeing in a museum in Western Australia timbers from ships that had hit the bricks in the mid 1600's. The displays included descriptions of how they had been preserved by immersion in PEG on being brought to the surface.
More at: http://www.mm.wa.gov.au/Museum/cons/cons.html

Whilst these guys are trying to stabilise timbers that are already past their use-by date, some of the theory must be relevant to preserving good wood.

Hans

[Tom Lathrop]

Dave,

On the subject of PEG, I know some woodturners who use PEG to stabilize green wood before turning. Ed Molthrop in Atlanta actually turns whole (500 - 600lb) tree stumps into vases that kids can get inside of. I have been in his shop and know that finishing is a problem for him. The PEG leaves a waxy surface on the wood that makes selection of finish kind of restricted.

He also says that PEG treated sculptures left outside in the elements will have some of the PEG leached out and the surface will errode.

[Dave Carnell]

Turners of very large burls, etc. have used EG to stabilize their pieces. The advantages of EG over PEG are:
EG leaves no surface coatings that interfere with finishing or gluing.
EG penetrates rapidly at room temperature. PEG has to be dissolved in water and has to be hot to get reasonable penetration rate, and to prevent its growing mold.
PEG does not kill rot, fungus, or insect infestations; EG does.

[Tom Lathrop]

Dave,

Why then do turners use PEG which is a lot more expensive than EG for stabilizing blanks?

What about the leaching issue?

Are you going to the Cape Fear wooden boat show?

What do you think about the tocic issue of pets/other animals with using EG on decks and docks?

[Bruce Hooke]

On the matter of PEG and old ships, the goal of this sort of use is fairly unrelated to what someone would be hoping to achieve by using EG on the wood in a newer wooden boat. As I understand the purpose of using PEG on the wood from sunken ships is to replace the water in the wood. Wood that has been at the bottom of the ocean for many many years is, of course, saturated with water and also somewhat detriorated. If it was allowed to simply dry out it there would be problems. So, the PEG is used to replace the water to in effect keep the wood saturated while being able to keep the wood in an indoor, climate controlled environment where it is easy to preserve, study and display.

[Tom Lathrop]

Bruce,

I could be in error, but I think the purpose is identical. The purpose of PEG in preservation is not to saturate the wood but to replace the bound water in the wood cells. Allowing the unbound water in saturated wood to evaporate creates no problem in deterioration that I know of. All dimensional and physical changes in the wood takes place after the unbound water has been removed. In most woods, this takes place below about 28% moisture content.

[Dave Carnell]

There are a number of papers in the literature showing EG and glycerol to be more effective than PEG in stabilizing wood. A. J. Stamm, who did the pioneering work on PEG showed that glycerol was more effective, but ignored the result; I think because it didn't fit his theory that it took a large molecule as a "bulking agent" in the wood.

Once the EG has soaked into the wood there is no toxicity problem.

About 15 years ago the NC Underwater Archaeology Unit at Fort Fisher gave me a musket/rifle butt recovered from a sunken blockade runner. They kept them submerged in water to prevent their falling apart. I replaced the water with EG antifreeze. The piece was perfectly stabilized, even to the chisel marks where brass trim had been inletted. THe weight was followed for several years. It kept diminishing to where the EG had to have almost completely evaporated and the piece stayed stable. It would have crumbled to bits if just dried. The EG can leach from the wood, but there is a competing strong attraction of the EG to the wood that apparently retains enough to kill rot organisms. I don't have the sophisticated equipment to prove this. However, when my first rope mat at the back door rotted to mush in a couple of years, I treated the replacement with antifreeze. It has not shown any deterioration in at least 10 years. Rotted white pine in a utility skiff was treated with antifreeze almost as long ago. Though the skiff lives in the water and often has rain water in it, there has been no further degradation. My surmise is that the concentration of EG lethal to one-cell organisms is very low.

When is the Cape Fear boat show?

[On Vacation]

Please let us know when the Cape Fear Boat Show is Dave.

[Scott Rosen]

What is the best way to purchase EG?

[Tom Lathrop]

I believe the Cape Fear show is on August 3. There is a fee of $25 for exhibiting a boat this year but that includes dinner.

Ethylene Glycol is common anti freeze.

Good to hear your experience Dave, I'm going to try it on my dock and deck. I know it would work best on green wood but I'll try anyway.

[Dave Carnell]

Tom,

Aren't your dock and deck already pressure-treated to at least ground contact loading?

Dave

[Tom Lathrop]

Sure Dave, but I thought the EG might retard the green stuff.

[Scott Rosen]

Excuse me for being naive about this, but wouldn't automotive anti-freeze have other additives that you might not want on your wood, like waxes and lubricants that would prevent paint and varnish from adhering?

[bugeye]

hi,
It doesn't seem to have any effect on paint and glue in my experience. The only warning that I can give is that you shouldn't put the antifreeze on something and hope to paint it the next day. It takes a long time for it to dry, and if you're having damp weather, it seems to attract moisture. Unless it is especially warm and dry, it seemms to take at least three or four days to get to where I feel good about painting or especially gluing.