# Anti-freeze to stop & prevent wood rot



## Cmack (Mar 20, 2009)

I am currently working on a resto project 16X48 Crestliner and found this article concerning ethylene glycol's effects on wood rot. I am thinking of soaking all the wood used in the project. Any thoughts.

Chemotherapy for Rot

Friday, February 13 2004 @ 06:43 PM EST
Contributed by: Dave Carnell
Views: 17847

Once rot gets a toehold in wood it is difficult to cure completely--- it is like a cancer. Digging out the rotted wood will still leave spores and water in the sound wood. After you fill in the cavity with something like epoxy, the rot continues to flourish underneath. Products promoted to make rotted wood sound and stop rot penetrate only until they meet water, with which they do not mix. Under the solid repair rotting goes on. With one exception (more later), the commercial products sold to treat dry wood to prevent rot are completely ineffective against established rot in wet wood because they are dissolved in petroleum solvents and oil and water do not mix.

There are two commonly available inexpensive materials that will kill rot in wood and prevent its recurrence. First, there are borates (borax-boric acid mixtures) which have an established record in preventing rot in new wood and in killing rot organisms and wood-destroying insects in infested wood. Second, there is ethylene glycol, most readily available as auto antifreeze-coolant. Glycol is toxic to the whole spectrum of organisms from staphylococcus bacteria to mammals. All of the published material on its effectiveness against wood-destroying fungi and insects that I am aware of is the result of my investigations over the past 15 years.

Both borate solutions and glycol penetrate dry and wet wood well because they are water-soluble; in fact, penetration by glycol is especially helped by its extreme hygroscopicity-its strong attraction for water. For both, the fact that they are water-soluble means they are not permanent solutions to rot in wood that is contnually exposed to water-below the waterline and in ground-where they will eventually be extracted-dissolved out.

I first was interested in glycol as a wood-stabilizing agent, where it is in many ways superior to polethylene glycol (PEG), and it was during this work that I realized the useful effect of glycol on organisms, though I was pretty dense in interpreting the first experiment.

The ladies immerse the stems of greenery such as magnolia branches in glycerin to keep them green. Glycol is very similar to glycerin in all its physical properties and much cheaper, so I stuck a magnolia branch in antifreeze. The next day it was brown. After the third attempt I tumbled to the fact that the glycol was killing the greenery.

This was the reason that glycol never replaced glycerin in applications such as a humectant for tobacco and an ingredient of cosmetics and pharmaceutical ointments, though it had all the desirable physical properties.

I had two 2" thick slabs of a 14" diameter hickory tree that had just been cut. I treated one with antifreeze and left one untreated. I was looking at wood stabilization, not rot prevention. After about six months stored inside my shop the untreated control was not only cracked apart, but it was sporting a great fungal growth, while the treated slab was clean.

The local history museum wanted to exhibit two "turpentine trees", longleaf pines that had many years ago been gashed to harvest the sap that made everything from turpentine to pine tar. The trees delivered to us after cutting were infested with various beetles and had some fungal growth. I treated them with antifreeze outside under a plastic tarpaulin every few days for three weeks. They were then free of insects and fungus and have remained so after being moved inside and installed in an exhibit over four years ago.

I took three pieces from a rotting dock float that were covered with a heavy growth of fungus, lichens, etc. I treated one with antifreeze painted on with a brush, the second with a water solution containing 23% borates (as B2O3), and left the third untreated as a control. They were left exposed outdoors and were rained on the first night. By the next morning the growth on the antifreeze-treated piece was definitely browning and the borate-treated piece showed slight browning. After two months exposure to the weather the growth was dead on the antifreeze- and borate-treated pieces and flourishing on the control.

I have a simple flat-bottomed skiff built of plywood and white pine, which has little resistance to rot. After ten years some rot developed in one of the frames. It may have begun in the exposed end grain. It consumed the side frame, part of the bottom frame, and part of a seat brace fastened to the side frame. The plywood gusset joining the side frame to the bottom frame was not attacked. I excised the rotted wood, saturated all with ethylene glycol antifreeze to kill all the rot organisms, and there has been no further deterioration in four more years afloat with wet bilges. I have not replaced any pieces, as I am building another boat that can replace it; that is more fun, anyway.

I have a 60+ year old case of the fungus infection known as "athlete's foot". Many years ago it infected the toenails extensively. The whole thing was pretty grotesque. My dermatologist and druggist both assured me there is no known cure. About six years ago I started using antifreeze applied under the nails with a medicine dropper about every five days. The professionals are technically right. I have not completely cured it, but the nails have grown out pink and thinned almost to the ends and I never have any trouble with blistering, peeling, or itching between the toes as I had had for six decades. No drug company is going to have any interest in this because the information has been in the public domain for so long that there is no opportunity for any proprietary advantage. The various wood-rotting organisms cannot be anywhere near as tough.

Glycol by itself has one big advantage over solutions of borates in either water or glycol. Glycol pentrates rapidly through all paint, varnish, and oil finishes (except epoxy and polyurethanes) without lifting or damaging those finishes in any way. You can treat all of the wood of your boat without removing any finish. The dyes in glycol antifreeze are so weak that they do not discolor even white woods. Once bare wood has been treated with glycol or the borate solutions and become dry to the touch it can be finished or glued. If a borate solution leaves white residues on the surface, it will have to be washed off with water and the surface allowed to dry.

This is my preferred process to treat rot. Once you find soft wood or other evidence of rot, soak it with antifreeze even if you cannot do anything else at the moment. Paint it on or spray it on with a coarse spray. Avoid fine mistlike spraying because it increases the likelihood that you will breathe in unhealthy amounts of glycol. Put it on surfaces well away from the really damaged wood, too. Use glycol lavishly on the suspect wood, which will readily absorb 10-20% of its weight of antifreeze.

Next dig out wood that is rotted enough to be weak. Add more glycol to wet the exposed wood thoroughly. Then add the 25% borate solution of the recipe below so long as it will soak in in no more than 2-3 hours. Then fill in the void with epoxy putty and/or a piece of sound treated wood as required. The reasons I use borates at all are: 1) it is a belt-and-suspenders approach to a virulent attack, and 2) over a long period glycol will evaporate from the wood; especially, in areas exposed directly to the sun and the high temperatures that result.

If there is any question about water extracting the glycol or the borates, you can retreat periodically with glycol on any surface, painted or bare, and with borate solutions on bare wood.

Glycol's toxicity to humans is low enough that it has to be deliberately ingested (about a half cup for a 150 lb. human); many millions of gallons are used annually with few precautions and without incident. It should not be left where children or pets can get at it, as smaller doses would harm them, and they may be attracted by its reported sweet taste that I have confirmed by accident. The lethal dose of borates is smaller than of glycol, but the bitter taste makes accidental consumption less likely.


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## Captain Ahab (Mar 20, 2009)

Looks like a lot of work (and reading :shock: ) Welcome to Tin Boats.


Just replace teh wood - if it is rotten it is likely also week - out in the middle of the lake is the last place you want to "test" old wood!


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## Gamefisher (Mar 20, 2009)

Shouldn't there be a concern about the toxic antifreeze leeching into the water?


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## ben2go (Mar 20, 2009)

This technique was mainly meant for wooden sail boats and power boats.Plywood will warp when soaked with the solution.


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## Zum (Mar 20, 2009)

Welcome to the site.
I'm sure you will get lots of replies to this topic.

My veiw....Interesting read,not to sure if I would want everyone with wood on their boats trying it,that would be alot of anti freeze on/in the water wouldn't it?(drinking water reservoirs)
Reminds me of the pentox(green)that you used to be able to put on your house decks.Glad to hear it works on your feet,hopefully your body can handle the toxicity of it.


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## Cmack (Mar 20, 2009)

Thanks for the welcome. I first heard of this several years ago and have used it on the transom of my fiberglass bass boat that had a wet (not rotten transom) and now after 5 or so years of a V-6 twisting on it, it's still solid and still damp from time to time. I was gonna be using some 2X2 and 2X4 material on the Crestliner that would be under the flooring and was thinking about soaking them to prevent rot. I have already laminated the wood for the new transom and sealed it with polyurethane or I would have tried brushing several coats of anti-freeze on it 1st. It simply slipped my mind....Cmack


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## Nickk (Mar 20, 2009)

antifreeze is nasty stuff(ethylene glycol), the nerve damage it causes isn't worth messing around with it in the event it's collective.


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## LarryA (Mar 20, 2009)

Personally, I don't like the idea at all. Our waters already have too much contamination in them without adding more. It stands to reason that these chemicals will contaminate any water that enters the boat and thus end up where they should not be after the boat drains or the pump would go on. Sure, there may only be a small amount from one boat, but what if every boat did this. The math would probably show that would be real bad for our fishing and recreation waters.


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## rfunfarm (Mar 22, 2009)

If there is concern about antifreeze in the lake--what about your boat wax or polish ? And that oil in the exhaust ??--Glycol in small amounts will do about the same "damage" as your polish & waxes.


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## redbug (Mar 22, 2009)

big differece between Anti freeze and wax 
I spoon full of anti freeze can kill a dog or cat..


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## rfunfarm (Mar 23, 2009)

Kit car wax was what killed my neighbors dog. Still don't see any difference--They are diluted in water to non deadly PPM's


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## rfunfarm (Mar 23, 2009)

My point is also simple--Lotsa boats = lotsa wax---Lotsa boats = lotsa oil in exhaust---One boat done with antifreeze = little antifreeze.   my 2 cents


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## Zum (Mar 23, 2009)

Trying so hard not to post again,just can't stop myself

rfunfarm you are probably right but the post was on antifreeze so were trying to stick to that.Us humans are terrible to the envoirment in so many ways and we could argue about it forever.

Antifreeze=poison=bad,if everyone started using it,probably real bad.
2,3,4...wrongs never make a right.

ps.Welcome to the site.


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## rfunfarm (Mar 24, 2009)

That is why we need NOT worry about a very few using antifreeze to refinish a boat. When 100's of thousands won't give up their motors for the environment. 1-2-3 hundred thousand wrongs don't make a right either. The antifreeze of "one" is the lesser of the "evils" PS- thanks for the welcome to the site.


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## Cmack (Mar 25, 2009)

So call me an environmental clod but, I'm gonna douche the framing in the boat with good ol' Prestone anti-freeze. Nuke the whales :lol: ......Cmack


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## Captain Ahab (Mar 25, 2009)

I think we can all agree this thread is about done!

Let it rest please


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## redbug (Mar 25, 2009)

I agree with ahab you asked for thoughts and everyne kinda said they would replace the wood then we get a screw you 
thanks for sharing


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## Cmack (Mar 25, 2009)

Sorry, didn't mean it as a "screw you". Just a bit of twisted humor......Cmack


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## Popeye (Mar 25, 2009)

If you are intent on using antifreeze, then I would suggest you use Propylene glycol and not Ethylene glycol as recommended in the below link.

https://www.bearfortlodge.com/bearfort_lodge/2006/12/log-home-repair-restoration-replacing-chinking-and-fixing-logs-part-vi-home-brew-wood-and-log-preservative/


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## Cmack (Mar 26, 2009)

Thanks Popeye, I may give that a shot. I will be using the solution on new material as a rot preventative. I am wanting to do this because there will being some wood lying flat on the ribs beneath decking and I have been told that treated lumber will cause corrosion if in contact with the aluminum. I used 5 coats of Spar polyurethane to seal the new transom, but it is much easier to get to than these boards will be. If I do go with ethylene glycol, I will wait until it is dried and try to seal it with polyurethane. Thanks again for the info.....Cmack


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## tuck (Oct 9, 2010)

A little off the "boat" subject, but pertinent to the "old" thread below.........does anyone know a safe way to protect an in-ground post from future rot? The posts are already in the ground and they are not pressure treated. They are in rlatively "dry gound" all the time as they are inside a dry barn.....but, of couse the soil still has some moisture underneath, thus the reaon for my concern.......


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## Popeye (Oct 9, 2010)

While not very "earth friendly", I used to work with my dad and when we put up fences, we dipped the buried ends in coal tar creosote. That is the black petroleum stuff railroad ties are soaked in to prolong their life. If you go that route, DON'T GET ANY ON YOUR SKIN. It burns and leaves a rash. Of course you probably can't even buy the stuff any more either.


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## cavman138 (Oct 11, 2010)

Man I always thought most fishermen/outdoorsmen were pretty concerned with the environment. The fact that antifreeze is even remotely considered seems a little off. I know people like to go to the extremes on things, but this is just too far.

PS Sorry Ahab, I got to the party a little late and felt the need to add my 2 cents. Maybe this will end it??


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