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Ethylene Glycol

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Hi folks, anyone know where I can buy pure ethlyene glycol (i.e. not anti-freeze)? I've read it's the business for dry rot in boats - kills the beasties and opens up the wood's 'pores' so to speak, making it more receptive to epoxy. Wouldn't have the first clue where to buy it though.

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It is just simple anti-freeze. In fact, the cheapest ones tend to be the more plain basic. The expensive ones are usually called Corrosion inhibitors. But even if it does have a bit of corrosion inhibitor in it it doesn't hurth anything. Now the one thing you do need to check is if it is a pure glycol or a ready to use, which is the glycol diluted with water to be used directly. Not an economical way of buying it diluted.

Ummm, never heard of it "opening up the pores" of timber before. I would be careful of such a claim. But after talking to motorbike yesterday, he also said he had heard that epoxy still adheares OK to timber treated with Glycol. I have never tested the theory, so can't say.

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Thanks Wheels, read some interesting things about it over the weekend. Also interesting to read that those expensive 'penetrating' epoxies (Everdure, CPES, etc) actually don't seem to work as well as plain old bog standard epoxy resin.


In case you're interested....







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Without reading the links first, the big problem with Evadure was descovered about 10yrs (or probably more now) back. That being of it being porous. The Solvent evaporating would leave "holes" in the epoxy and it was found that timber coated in the stuff still took on water. It is also debatable as to whether the biocide in Evadure actualy helps or not. Sure it kills mould, but the epoxy pretty well locks it up anyway.

A coating of a low viscosity solvent free Epoxy will work just as well in many situations. But if you want to penatrate into timber, a bit of solvent in Epoxy, or the premade versions will work OK, as long as you overcoat again later with a pure undiluted coat to water proof the surface.


BB, have you got a problem with some rot??? There are also timber preservatives like Metalex. the advantage of Glycol, is that (apparently) it will absorb right through paint.

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by Dave Carnell - check out his web site.


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.


Borate Wood Preservatives

Commercial and Home-Brewed


Tim-Bor®: about $3/lb. plus shipping.


Ship-Bor®: Same as Tim-Bor®; $19.95/lb. plus $2 shipping.


Bora-Care®: $70/gal. plus shipping.


Home-Brew Water Solution of Borates: Based on U.S. Navy spec. of 60% borax-- 40% boric acid (this ratio gives the maximum solubility of borates in water); 65% water, 20 %borax, 15% boric acid; 15.8% borates; borax costs 54 cents/lb. (supermarket), boric acid costs about $4/lb. in drug stores (sometimes boric acid roach poison, 99% boric acid, is cheaper in discount stores); equiv. to Tim-Bor® or Ship-Bor® at 30 cents/lb. To make this solution mix the required quantities and heat until dissolved. The boric acid, in particular, dissolves slowly. This solution is stable (no crystals) overnight in a refrigerator (40°F.), so can be used at temperatures at least as low as 40°F.


Home-Brew Glycol Solution of Borates: 50% glycol antifreeze, 28% borax, 22% boric acid. To make a stable solution you mix the ingredients and heat till boiling gently. Boil off water until a candy thermometer shows 260°F. (This removes most of the water of crystallization in the borax.) This solution is stable at 40°F and has a borate content of 26%. With antifreeze at $6/gal. and borax and boric acid prices as above, this costs about $15/gal.

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The Effect of Ethylene Glycol and Sodium Borate Solutions on the

Adhesion of Epoxy to White Oak and White Pine Samples.


Dan Freel, Chris Maples, Bruce Niederer,

William T. (Chip) Reynolds, and James R. Watson




The search for low toxicity wood preservatives results in the use of products that may affect the adhesion of finishes and glues in wood construction. Ethylene glycol and sodium borate are two such products that have been used singly and in combination for their fungicidal qualities. This paper reports the results of tests of solutions of these compounds in varying concentrations. Results indicate that a 75% ethylene glycol/25% sodium borate solution has a marked detrimental effect on the adhesion of epoxy to white oak, and to a lesser extent reduces adhesion of epoxy to white pine. Other concentrations of ethylene glycol and water increase adhesion of epoxy to wood substrates. Recommendations are provided for the use of WEST SYSTEM® 105/206 epoxy on white oak and white pine that has been treated with various concentrations of these solutions.




With the heightened environmental awareness of today's society, both professional and amateur boat builders and restorers have begun searching for wood preservatives of minimal environmental and occupational safety impact. Wood preservatives of relatively high toxicity have been in use for decades, as a prophylactic in new construction and as a remedial treatment in repair and reconstruction. The effect of such preservatives on adhesion of finishes and glues is reasonably well known.


Both sodium borate and ethylene glycol solutions have been promoted as low toxicity preservatives for use in timber frame construction and marine applications, and as low toxicity fungicides and termaticides. The efficacy and limitations of these solutions in preventing wood deterioration is well documented. However, other than anecdotal experiences and the assurances of producers, little information documents the effects of ethylene glycol and sodium borate solutions on the adhesion of finishes and glues.


The Gougeon Brothers lab has adhesion data from seven years of standardized testing of various wood and epoxy combinations. Tests have included the use of WEST SYSTEM® epoxies as both adhesives and coatings. Relevant to the instant experiment, in 1991 Gougeon Brothers tested the effects of oil based, alcohol based and water based stains on the adhesion of epoxy coatings. These tests indicated that with oil based stains adhesion can be seriously jeopardized, while adhesion is satisfactory with alcohol and water based stains.


This paper relates the results of a preliminary test of WEST SYSTEM® 105/206 epoxy adhesion to substrates of white oak and white pine treated with solutions containing varying concentrations of ethylene glycol, sodium borate, or both. While the results described below are promising for the use of certain solutions in combination with WEST SYSTEM® 105/206 as a bonding or coating agent, further testing is needed to better report definitive effects on adhesion and bonding strength.




The Pneumatic Adhesion Tensile Testing Instrument (PATTI) manufactured by SEMicro Corporation is the standard instrument used by Gougeon Brothers to determine the adhesion strength of epoxies on various substrates. In addition to internal standardization within Gougeon Brothers labs, the PATTI conforms to the American Society for Testing and Materials 'Standard for Pull-off Strength of Coatings Using Portable Adhesion Testers' ASTM Standard D 4541-85(89). The ASTM standard provides the procedure used by Gougeon Brothers to determine adhesion strength of epoxies on various substrates.


Lengths of 1"X6" white pine and white oak panels served as the substrate for testing to provide an indication of adhesion in soft wood and hard wood. The panels received one of five treatments, listed below.


Control - no treatment provided.

75% ethylene glycol / 25% sodium borate

50% (75% ethylene glycol/25% sodium borate) / 50% water

50% ethylene glycol / 50% water

100% ethylene glycol

Within each treatment group the panels were tested. Each solution was applied to the flat of the test panel by hand with a small paint brush to ensure maximum absorption. The panels dried at room temperature for three days prior to bonding the PATTI studs.


In summary, the PATTI applies an aligned and controlled force, applied by pneumatic pressure, to an aluminum cylinder (called the 'stud') attached to the surface being tested, until reaching a maximum force or failure. The PATTI provides a gauge that translates the pneumatic force into pounds per square inch of force. The attachment of the stud is controlled to ensure strict conformity between samples. The stud, about _" in diameter, is etched with WEST SYSTEM® 860 two step etching solution prior to bonding, then bonded to the surface being tested with the requisite epoxy, and allowed to cure appropriately. In this instance, WEST SYSTEM(R> 105/206 was used as the bonding agent, and allowed to cure at room temperature for two days prior to testing.


Test Results


Test results for the samples are presented as the average value of the three samples within each treatment group. The data present both the pounds per square inch (p.s.i.) of force applied at failure, and the percent of wood failure within the area of bonding (at increments of 5%). These measures provide both a quantitative measurement for comparison and a qualitative sense of the integrity of the bond.


Solution applied Adhesion p.s.i. at failure % Wood failure

White Oak

1. Control 1625 68

2. 75% e. glycol/25% s. borate 579 10

3. 50% (75% / 25%)/50% water 1285 48

4. 50% e. glycol/50% water 1774 80

5. 100% e. glycol 1380 38

White Pine

1. Control 661 100

2. 75% e. glycol/25% s. borate 511 100

3. 50% (75% / 25%) /50% water 620 100

4. 50% e. glycol /50% water 701 100

5. 100% e. glycol 756 100

Discussion and Conclusions


The results presented herein cannot be viewed as definitive, but do provide good illustration of certain areas where the ethylene glycol and or sodium borate may be appropriately used. This test examined only white oak and white pine, and while indicative of the results that may be found in other woods, one cannot extrapolate with confidence from these results to other woods.


Certain results also do not lend themselves to an intuitive explanation. For example, many plausible reasons could be presented for increased adhesion under certain test solutions, but none can be validated based on the results presented herein.


We have no explanation for why the 75% ethylene glycol/25% sodium borate solution results in such diminished adhesion, on both the soft and hard wood. A better understanding of this phenomenon requires further testing, with particular attention to the testing of various sodium borate solutions alone and in combination with ethylene glycol. It may be that the sodium borate leaves a residue that affects adhesion, but this interpretation is speculative.


Further testing of the 75%/25% solution would be of value, given that some recommend the use of these two chemical additives in common to attain greater penetration of the wood treated (due to the effect of the ethylene glycol) and longer lasting preservative qualities (due to the effect of the sodium borate). Indeed, certain proprietary products tout the benefits of this combination of preservatives.


Even in the absence of statistical analysis, it is clear that application of the 75% ethylene glycol/25% sodium borate solution results in a significant loss of adhesion. This is especially true with the white oak substrate, where the loss of adhesion is sufficient to jeopardize bonding for structural purposes. The minimal wood failure with the 75%/25% solution and white oak substrate also calls into question the applicability of this combination even for applications limited to coatings.


With any but the 75%/25% solution and white oak, one may safely use WEST SYSTEM 105/206 for coating applications. On white oak treated with the 50% e. glycol/50% water solution, one may safely use WEST SYSTEM 105/206 for bonding applications.


The situation with respect to the white pine is less definitive. The loss of adhesion under the 75%/25% solution is less dramatic than with the white oak, and the white pine still shows 100% wood failure. Even so, in structural bonding applications one would be wise to adopt a conservative approach and avoid using the 75%/25% solution. With any of the solutions and white pine, one may safely use WEST SYSTEM 105/206 for coating. With any but the 75%/25% solution and white pine, one may safely use WEST SYSTEM 105/206 for bonding applications.


Given the differing bonding and solution absorbing characteristics of various wood substrates, it is unwise to extrapolate from these results to other woods. Those interested in using sodium borate or ethylene glycol solutions as preservatives in combination with other woods are advised to test samples with the solution to be used.


Gougeon Brothers, Inc.


P.O. Box 908

Bay City, MI 48707-0908

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Hi Wheels, sadly it looks so. Tried to dry out the keel floor and paint over it a couple of years ago (knowing no better as I did at the time) and of course the paint has cracked and peeled, leaving the wood open to moisture again. So this time I am determined to do it properly. Sadly though ethylene glycol seems to have a hard time penetrating epoxy or urethane paints (which of course I painted my bilge with), so I'm going to have to scrape it all off again I think. Plus the wood under the paint is still wet, while the exposed wood has now dried out after a couple of weeks on the hard with heaters going. I'll get a friendly boatbuilder to look at it tomorrow (I'm in the yard just now anyway, so might as well).

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Get the paint cleaned off and allow it to dry and then see what is soft.

As Motorbike found with his, the black stuff was not actually rot, but old sump oil and diesel that had soaked into the timber and softened it up.

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scrape the paint use a dehumidifier for a day or 3 to dry out the bilge, then check for rot as Wheels suggests.

Re soaking epoxy into ply or any soft wood for that matter, a local boat builder suggested using epoxy mix diluted at 75% with meths x 2 applications, this allows the epoxy to get good penetration, then 1 coat of normal strength epoxy, sand and paint if so required.

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