Ethylene Glycol as a wood preservative

[Trevlyns]

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. :)

[kengrome]

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?

:)

[TerryKing]

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...

[kengrome]

Kenneth, do you typically use 100% Ethylene Glycol when you apply it, or more like 50-50 with water?Hi Terry, I use a 50/50 mix although I suspect that using it 100% would be just fine, too.

West's tests showed a small difference in adhesion, on pine as I recall.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 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.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.

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

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...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.

[Trevlyns]

Sincere thanks Kenneth and Terry for the prompt and detailed replies. I also came across this article (http://www.boatbuilding.com/article.php/ChemotherapyforRot)which may be of interest to others in subsequent research.

[TerryKing]

I also came across this article (http://www.boatbuilding.com/article.php/ChemotherapyforRot)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...

[Meanz Beanz]

Ken,

Could you estimate coverage?


Cheers
Mbz

[kengrome]

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.

[Meanz Beanz]

Thanks Ken...

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

Cheers
MBz

[TeddyDiver]

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

[alex folen]

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.

[TerryKing]

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/MaterialsForBoatbuilding#Paint_and_Epoxy_Adhesion_VS_Preservative_Treatments

[pittendrigh]

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? ...........



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.

[TeddyDiver]

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

[Frosty]

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.

[Saildude]

Deadly to people also - I think the reason pets like EG is that it tastes sweet - I think I remember reading that many manufactures add a bitter taste agent to EG so it can't be drank.

[Frosty]

So they make it taste bad so you cant drink it?-- but its deadly anyway.

[Saildude]

I think there have been a lot of accidental poisonings for small kids and pets.

[Frosty]

How do you know it tastes sweet? and how do you know it was accidental?

Wood preservative is getting scarce (in Europe)--probably because of its alleged poisonous capabilities, however antifreeze EG is not available where I am either,- it barely drops below 26 degrees c

When the day comes we cant buy anything, what will we do.

[Lurvio]

From what I've heard, many of the kids poisonings happened because the dad stored some amount of the green stuff in soda bottles, that stuff and a familiar packing is a bad combo. :)

Lurvio

[Ilan Voyager]

The mono or poly ethyleneglycol is sweet because it has a glycol base which is a sugar. But it's a poisonous sugar which destroys the kidneys or disrupts the cellular function of any animal or vegetal, mono or poly cellular. In fact it kills everything, and many accidents have happened with children and pets (specially dogs who like sugar taste); it's well documented fact and MDS sheets will give information.So now in the antifreeze a bitter agent is added to make the antifreeze unpalatable.

On the other side the polypropilene glyco is not so poisonous and it's used as hygroscopic agent, for example in the pipe tobacco, but it won't disinfect the wood.

Ethylene glycol is used with a borate salt (generally a sodium octoborate) to get a triple effect: the ethylene glycol will kill everything even the fungus spores but it will evaporate, the borate salt wich is a non-volatile mineral will remain in the wood for definitive protection, the hygroscopic action of the ethylene glycol will help the borate salt to migrate further into the wood by osmosis.
A curcuma test will show the degree of penetration of the borate into the wood.

A wood treated with the ethylene glycol-borate mix cannot be "epoxified" as the adhesion is too poor. Same thing with the antifreeze-borate mix as the antifreeze containsproducts (metallic salts and others) to improve the anti corrosion effect which impedes the adhesion of the epoxy.

The "pure" monethylene glycol/water solution works very well to disinfect wood (the effect won't last) and improve gluing. The epoxy resin is applied after a complete drying of the treated wood.
I do not think that the adhesion improvement comes from giving a mechanical key ("opening the pores") but by a better chemical and molecular bond between the cellulose (also a sugar)/lignine (with a lot of phenols) of the wood and the epoxy resin which is a phenol derivate.
(Pierre Gilles de Gennes made the ground breaking research on the subject of adhesion, and you will find on Internet excellent resumes on the physics of adhesion)
Forest Products Laboratory http://www.fpl.fs.fed.us/ has a lot of excellent papers about adhesion of glues (with a good corpus about epoxies) on wood and many other wood related subjects, like preservatives (and borates). A search in the index is worth...
There also excellent papers in French and German.

Frosty: Antifreeze is used in engines not only for protecting for freezing, but also for improving the heat capacity of the cooling medium (boiling will occur at 127 Celsius instead of 100) and to protect the engine components from corrosion, plus lubricant for the pump's seals, anti foam agents and detergents.

The use of pure water (and worst: tap water) is the best way to kill a modern engine (and even the old ones). It will overheat as the radiator is sized for anti freezing high boiling temp. Also the electrolytic corrosion of the engine, composed of different metals (steel, iron, aluminum and copper alloys) will destroy first the aluminum components. Add a good sludge of oxides and salts obstructing the radiator and the picture is almost complete...

[Frosty]

Frosty: Antifreeze is used in engines not only for protecting for freezing, but also for improving the heat capacity of the cooling medium (boiling will occur at 127 Celsius instead of 100) and to protect the engine components from corrosion, plus lubricant for the pump's seals, anti foam agents and detergents.

The use of pure water (and worst: tap water) is the best way to kill a modern engine (and even the old ones). It will overheat as the radiator is sized for anti freezing high boiling temp. Also the electrolytic corrosion of the engine, composed of different metals (steel, iron, aluminum and copper alloys) will destroy first the aluminum components. Add a good sludge of oxides and salts obstructing the radiator and the picture is almost complete...


Yeah --kinda-- some engines maybe depends on the pressure of the rad cap, lubricates water pump, not really they still wear out, probably more due to improvements in pump design. I use water with a bit of diesel in it

Shock horror gasp,--

You wont remember the Triumph stag engine I suppose but hey we are going way too far off topic here.

[TeddyDiver]

Thanks Ilian of good info. A couple of remarks thou..

Frosty: Antifreeze is used in engines not only for protecting for freezing, but also for improving the heat capacity of the cooling medium (boiling will occur at 127 Celsius instead of 100) ....

The use of pure water (and worst: tap water) is the best way to kill a modern engine (and even the old ones). It will overheat as the radiator is sized for anti freezing high boiling temp...


The heat capasity of Ethylene glycol is actually worse and it's not recommended to use over 50% solutions. Otherwise engine will die for sure. What radiators are designed for in this regard is the higher temperatures and flow not size..
http://www.engineeringtoolbox.com/ethylene-glycol-d_146.html

[Ilan Voyager]

I never wrote about using a 100% ethylene glycol in a engine, that would be stupid. I wrote antifreeze which is a solution of water and ethylene glycol.

Radiator (and heat exchangers for boats) are sized on the following requisites:
-Quantity of heat to dissipate (directly linked with the HP)
-Acceptable general temp of the coolant inside the engine: 95° Celsius in gas engines, 85° Celsius in Diesel engines. Temp may be greater in some local points, so the interest of high boiling coolant medium or you can have vapor bubbles in the system.
-Caloric capacity of the coolant fluid.
-materials of the engine and the radiator.
-efficiency circulation losses of the circuit. (thermostat, design of the tubing in the radiator etc...)
-Plus some other details.
-Temperature of the air or water.
That gives you the size of the radiator or heat exchanger. A cooling system made in aluminum or 10% cupro nickel, pressurized, with a high ebullition temp coolant is far smaller than an ordinary water radiator as you can work as hot as possible without risk of vapor bubbles...The size is a direct consequence of the flow and coolant medium (antifreeze...but you can use also an oil, it has been done also)

For sure the radiator itself and the tubing has to be designed to withstand the higher temps and pressure. It's evident. I've sized and built a few heat exchangers...

Frosty; most -modern- engines rely heavily on the antifreeze properties for cooling. And with "pure" water remains the problem of the electrolytic corrosion; generally the aluminum cases of the pump and the thermostat are the first to fail.
In all aluminum engines is the engine itself...

[Frosty]

I never wrote about using a 100% ethylene glycol in a engine, that would be stupid. I wrote antifreeze which is a solution of water and ethylene glycol.

Radiator (and heat exchangers for boats) are sized on the following requisites:
-Quantity of heat to dissipate (directly linked with the HP)
-Acceptable general temp of the coolant inside the engine: 95° Celsius in gas engines, 85° Celsius in Diesel engines. Temp may be greater in some local points, so the interest of high boiling coolant medium or you can have vapor bubbles in the system.
-Caloric capacity of the coolant fluid.
-materials of the engine and the radiator.
-efficiency circulation losses of the circuit. (thermostat, design of the tubing in the radiator etc...)
-Plus some other details.
-Temperature of the air or water.
That gives you the size of the radiator or heat exchanger. A cooling system made in aluminum or 10% cupro nickel, pressurized, with a high ebullition temp coolant is far smaller than an ordinary water radiator as you can work as hot as possible without risk of vapor bubbles...The size is a direct consequence of the flow and coolant medium (antifreeze...but you can use also an oil, it has been done also)

For sure the radiator itself and the tubing has to be designed to withstand the higher temps and pressure. It's evident. I've sized and built a few heat exchangers...

Frosty; most -modern- engines rely heavily on the antifreeze properties for cooling. And with "pure" water remains the problem of the electrolytic corrosion; generally the aluminum cases of the pump and the thermostat are the first to fail.
In all aluminum engines is the engine itself...

So you saying that adding Eg will make the 'coolant mix' less electrolytic than water itself.

[Ilan Voyager]

No! the EG has not anti corrosion properties.

It's the antifreeze made for cooling engines that has the additives (silicates, phosphates and others) for the corrosion inhibition purpose.
http://en.wikipedia.org/wiki/Antifreeze.

Coming back to borate salts for preserving wood , I can say that works pretty well. A deposit of 57 grams/square meter makes the wood totally unpalatable to Formosan termites, the worst ones...

I built my house 10 years ago with a cheap pine treated with borates. Not insect nor fungus have attacked the wood. I do a survey every six months as I live in a humid tropical climate where any piece of non treated wood (except 2 species) is destroyed in the following year by the termites, plus fungus (dry rot) and a big bunch of wood borers.

The solution EG/borates works very well for rot fungus on old classic boats as it penetrates deeply in "wet" wood. Works also on any porous wood (the oily woods repels waterborne products, and the very dense like zapote or moabi do not absorb any treatment).