Ethylene Glycol as a wood preservative

Hi fellas!

I was just reading in the boat design wiki on this site about Ethylene Glycol – more commonly known as automotive anti-freeze. Has anyone had any experience with this?

I’m busy with a stitch and glue ply composite project and was thinking in terms of its application. I’m going the traditional glass/epoxy route for the exterior of the hull but am now curious about the interior above and below the waterline. Is it simply applied direct and does it dry and seal the wood? Does it need further priming and or painting? I know there’s a wealth of knowledge out there and any input would be greatly appreciated.

Thanks in anticipation.

 

Hi Trevlyns,

There's more than one type of anti-freeze so if you're going to use anti-freeze be sure to use the stuff that is made of Ethylene Glycol – not Propylene Glycol and not any other type of glycol. I prefer using pure Ethylene Glycol from a chemical supplier because it will not have any "water pump lubricant" or any other engine additives in it that might create problems with the epoxy's bond to the wood.

A 50/50 dilution of EG has been shown by West Systems to enhance their epoxy's bond with the wood they tested in on. I suspect the same effect will occur with most other epoxies. Dave Carnell (retired professional chemist) thinks this enhanced bonding occurs because the EG "opens the pores" in the wood thus allowing the epoxy to soak in deeper.

Ethylene Glycol is not a primer, sealer, coating or drying agent. After applying it you should give the wood plenty of time to dry out before using adhesives, finishes or sealants. Just finish the boat as if you didn't even use EG and you'll be fine.

I usually epoxy encapsulate the wood in my boats after treating it with EG because my theory is that this will effectively entrap the EG in the wood and provide the longest lasting protection against rot. Unfortunately I haven't been using it long enough to know if this is true or not, but from a logical basis it seems to "make sense".

On the other hand, you can just as easily leave the inside of your boat bare so you can repeat your EG treatments on occasion by brushing it on the inside of the hull every so often. You can even paint the inside of your boat with
common paints such as 100% acrylic latexes and oil-based enamels then re-treat through the paint because EG molecules are small enough to pass through the above types of paints. Note that this won't work if you use epoxy or polyurethane based coatings since these chemicals do not let the EG through.


Do not heat or spray Ethylene Glycol because these actions will vaporize it, then you might inhale enough to make you sick or worse. Just apply it at room temperature with a brush or roller and it won't hurt you permanently even if you splash it on your skin or get it in your eyes. Some people might feel a stinging sensation if this happens, but that irritation goes away when they wash it off.

I don't usually bother with protective gear while using EG because it does not absorb into the skin readily, and I do not drink it. Nevertheless I would strongly recommend that you use gloves and eye protection and keep it out of reach of children and pets so they don't poison themselves accidentally. Better safe than sorry, right?

 

Preserving wood...

Kenneth, do you typically use 100% Ethylene Glycol when you apply it, or more like 50-50 with water? West's tests showed a small difference in adhesion, on pine as I recall.

I agree that as a preservative it would retained inside an epoxy encapsulation, waiting for a damaged area to let in some water and micro-organisms. Too bad some manufacturer didn't use it a decade or two ago on 'fibreglass' boats whose stringers and motor mounts are now turning to mush. We'd have a proof-of-concept example if they had, and their models did well.

After rescuing my 29 year old boat a decade ago with glycol, I simply get out the 1 quart spray bottle of glycol and retreat the frames and interior plywood twice a year.

What's in a word?? Anyone interested, look at: http://en.wikipedia.org/wiki/Ethylene_glycol

VS Propylene glycol, which is used in toothpaste, Dr. Pepper, etc.

The recent poisonings in Central America, and the clampdown on Chinese imports are the result of greedy merchants substituting cheaper Ethylene Glycol for Glycerin or Propylene Glycol...

 

Hi Terry, I use a 50/50 mix although I suspect that using it 100% would be just fine, too.

Yes I think it was pine. I don't remember all the details in the West Systems tests, but I do remember choosing the mix that gave the best epoxy bonding results. Too bad they didn't test other wood species, but they could never test them all anyways, so I'm assuming that their test results will be similar for the Meranti I'm currently using.

Obviously West Systems knew that EG was a very efffective rot preventer or else why would they have been testing it in the first place? I wish they had tested Copper Naphthenate as well, because that stuff is known to protect against rot and bugs and last a long time. Unfortunately most CN-based preservatives use an oil-based carrier which I presume will degrade the epoxy bond, so it doesn't seem like it would be as good as Ethylene Glycol to me.

I agree with this, and it is really a shame that I have never heard of one plastic boat builder with the forethought to treat the wood they use in their transoms and stringers with some kind of rot prevention chemicals. Of course having said this, I can rest assured that someone will prove me wrong ...

I certainly do not have to treat my wood with EG, but if I do then maybe it will prevent rot for years -- or decades or forever. Sure, it costs more in materials and labor, but I would rather build better boats than the junk some production factories are turning out these days.

If you keep this up you will never see any rot in your boat, no matter how wet it gets!

I hadn't heard about this, but there's always a greedy person somewhere who will "do the WRONG thing" to put a few extra bucks in his pocket, isn't there? Asia is well known for cheapening products like this -- especially China -- but this is going a bit too far if you ask me.

 

Sincere thanks Kenneth and Terry for the prompt and detailed replies. I also came across this article which may be of interest to others in subsequent research.

 

Thanks for the pointer to Dave Carnell's info; I previously abstracted some of his info from his site and personal correspondence and put it in the WIKI here.I'll add that pointer also...

 

Ken,

Could you estimate coverage?


Cheers
Mbz

 

I had it written down a long time ago, but there's no way I will ever find it now. From memory I seem to recall getting coverage of 3.5 sheets (7 faces) per liter for the Meranti plywood we use here -- standard 4' by 8' sheets of course.

 

Thanks Ken...

Ever heard of anyone actually having problems with epoxy and the automotive Ethylene Glycol or are you just being wary?

Cheers
MBz

 

Another article http://www.maritime.org/conf/conf-reynolds-mat2.htm

 

Keep in mind ethylene glycols are used in the manufacturing “as intermediates” of certain polyester resigns, methacrylate and urethanes. Don’t get confused with “it is compatible”. Testing is the only way you can assure yourself of epoxy adhesion. Without experimentation I can say that a glycol saturated piece of plywood, for example, would not have the adhesions properties expected, so be cautioned here. Any substrate having somewhat porous properties and is clean and dry of any oils, wax and other slippery stuff will have better adhesions. Epoxies are designed for a clean application, no residual glycols. You may get lucky and find a composition of epoxy that will incorporate the EG but the odds are a few and far between. If it has been done with tests to back it up then so be it, following it EXACTLY. In the testing above, site provided by Teddy Diver;

‘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.”

They seem to be on the right track as sodium borate is a salt and acts like one. Perhaps reducing the Borax conc. may allow better adhesion? An excess would cause the reaction to not fully react and residue may result. A residue on a surface would indeed hinder adhesion. When sodium borate is in contact with H2O, Hydrogen peroxide is produced thus having the preservative qualities. Sodium borate also acts as a buffer keeping the PH up thus allowing an epoxy to harden differently as the PH should be consistent as per epoxy manufacturing.
If you do not follow a scientific experiment to the “T” then my guess would be to allow the EG (only) to fully dry into the plywood, or wood. This will allow the epoxies to penetrate and adhere better. Testing is also advisable regardless.

 

Borate seems to be the problem with adhesion

The West Epoxy article says:

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.

(Emphasis mine). My personal experience has no adhesion failures on Glycol-treated plywood. But the tests mentioned are better data....

Also look at the Wiki here:
http://www.boatdesign.net/wiki/Mate...and_Epoxy_Adhesion_VS_Preservative_Treatments

 

If you build a composite boat, and if you use honeycomb core (Plascore or Nidacore) for the core material instead of plywood, then you do not have to think about moisture penentration and entrapment, and you do not need to worry about rot either. You can build a honeycomb core hull and still trim out in wood. Or you can build all seats and lockers using honeycomb core as if it was plywood. If you do, you also end up with a substantially lighter boat, as well more long-term durable.

 

Nothing to do with the subject here pittendrigh.. Better you to read the what's the name of the thread before posting OT...
BR Teddy

 

I believe its not so much a wood preservative but a chemical is in in that stops crawlies from eating it. If that the same thing or not?

Apparantly dogs and cats love the stuff -I don't know wether that's due to its bright green colour but it does look thirst quenching,--however it is deadly to them. I don't know about us.