Using Epoxy to Stop Wood Rot

[JeffHale]

I am starting to work on the interior of a 20 year old sloop that has spent the last 18 years on the hard. Most of the wood appears structurally sound, but with numerous water streaks and surface mildew throughout. Thought about using one of these “penetrating” epoxies (such as CPES—made by the Rot Doctor, at www.rotdoctor.com--or MAX PCR—made by Polymer Products and sold on eBay—or WoodEpox—made by Abatron, at www.abatron.com) and saving most of the wood, but have received information from these companies very different than others.
The “high solids” epoxies (such as West and Bote Cote) claim to be far stronger and say that adding solvents (“thinners”) to reduce viscosity and increase penetration is unnecessary, and only (1) greatly reduces the strength of the epoxy and (2) leaves holes (where the thinner has evaporated) that water can later enter. By contrast, these penetrating epoxies say their products are (1) made from wood resins rather than hydrocarbons and are less brittle, and glue the remaining fibers back together, and restore useful strength back into the wood, without changing the natural flexibility of the wood; and (2) the solvents actually mix with and force the evaporation of excess moisture from within the wood.
Does anyone have more information on this issue? Also, does anyone know how these three “penetrating” epoxies compare against each other? Any information appreciated.

[Alan Wheeler]

Firstly, You can't get epoxy made from wood. Epoxy is epoxy and is made from hydrocarbons. Now that is not saying that company does not have a product that is made from wood, but it ain't epoxy.
Secondly, yes solvents evaporating do indeed leave pores that water can migrate through. Using low viscosity resins will soak in just a s well as the solvent diluted ones do. Infact, the solvent diluted resins have very poor penatration in side grain but will flow freely down end grain. But so will pure resin.
Epoxy will not "seek out" water and expell it. Epoxy will not adhere to wet wood.
The epoxy timber preservatives often have a boicide in them to stop rot anf fungal growth. Debateble how efective it is. I have a better solution... read on below.
I am sorry I do not know the three products you have listed.
Some questions though,
Have you actually got Rot?? or is it just some mildew and good solid timber still??
If the timber is solid, but just damp from water penatration and mioldew or there is a little rot and you want to stop it spreading, you can do something compleatly different. Get Polyethelyne Glycol, automotive antifreeze and paint it over the timber. If you have a standard paint system, in other words not epoxy based, you can even paint it or spray it on over the paint. It will not damage the paint, but will be absorbed right throught the paint. Glycol is hydroscopic and will "seek out" and follow moisture, thus it will penatrate deep into wet timber. It kills fungus and insects like termites dead in their tracks and will continue to preserve the timber. You can then coat over with epoxy and protect the timber for good. It is cheaper and easier to use than Borax and is slightly safer to use. Although you do need to use a spray mask if you spray it, as it is poison.

[hellosailor]

Jeff, everything I've heard from the makers and users says that using thinner with conventional epoxy just isn't a great idea. If the epoxy could be made thinner...they'd make it available that way, or recommend thinning it if they could stand behind using it that way.

On the other hand, I did use GitRot some years ago and it turned rotted wood into "fiberglass" more or less. Really soaked in and left it strong. From what I understand, CPES and the other new products (which didn't exist that many years ago) are all engineered to work this same way, really spreading into the wood far deeper and wider than thinned epoxy would.
If you can't scarf out the rot and make a conventional repair, they seem like the way to go. IIRC CPES has some comparison files on their web site, but you can certainly buy a pint of this and that and try your own comparison on some 2x4 scrap if you want to see it up close and personal. If you are doing extensive repairs, I'd say it is probably worth doing that so you can judge for yourself.

As Wheels says, you need to first confirm if what you have is cosmetic (surface) or structural (deep). A tap hammer is some help but the ultimate test for rotted wood is still an icepick as far as I know.

A 1980's vintage wood boat? Was this someone's home-built project?

[cat man do]

I always thought that metho was an acceptable thinner for epoxy.

Rot job's i've repaired on other peoples boats i've cut the rot out, given the affected area a drink of metho and let that evaporate away, used a 10% metho/biocide mix combined with the epoxy to saturate the area, and then scarf in a new peice of timber or if a small bit, glue powder.

Haven't had to do a warranty job yet

Dave

[delmarrey]

Originally Posted by cat man do

I always thought that metho was an acceptable thinner for epoxy.

I use MEK with good results!

[cal40john]

West Systems has done some research with their product.
Go to WEST SYSTEM Epoxy and type "thinning" in the search box to find the article.


John

[Kapena]

Actually you have hurt the water resistance and the strength of the epoxy and haven't done anything to improve the strength of the wood.

Adding a solvent is never a good idea.

Thinning West System Epoxy

Sorry John you beat me to it.

Antifreeze is also a no-no.
Wood Boats-Wood based epoxy products to repair and resist wood rot.

"Finally, there is antifreeze with its glycol base. Claims are made that this is a bactericidal/fungicidal mix, although it is not approved for this by the EPA. Assuming that the claims are correct, the glycols have the same problem as the borates, that is, they eventually leach out of the wood, and have the added problem of contaminating the wood with glycol. No manufacturer of surface coatings or bonding agents of any type will guarantee their product’s effectiveness on a surface that has been treated with antifreeze. We do not recommend its use."

[cat man do]

My last cat was started with West System epoxy and we read the same blurb as posted here.

When it came to glassing plywood, we found that after full cure we could peel the glass from the ply quite easily.

Adding 10% metho[denatured alcohol] to the mix, and coating the ply first, and then glassing we actually pulled timber veneers away from the ply, or the glass tore.

We don't use West product's anymore, as they seem to work no better than some other product's that we can get for 1/2 the price

Dave

[JeffHale]

Thanks for inputs. Doesn't sound like most people have tried these "new" products, but those that did found them helpful. Mixed reviews on solvents (AKA thinners); maybe a chemist will know whether their evaporation leaves holes big enough for water to enter.
For Alan Wheeler--yes, actual rot in some places, esp. on flooring. If wood kept, would need to use epoxy filler. Thanks for idea of polyethelyne glycol--although that, too, appears controversial. Isn't that in essense another type of solvent, which one of these new products claims helps displace water and cause it to evaporate? Also, didn't say these new products claim epoxy made from wood--only the resins. To quote the claim of one manufacturer: "The basic resins from which our epoxy products are formulated are derived from wood pulp because this kind of resin approximates the toughness and flexibility of the original wood."
For hellosailor: I'm working on interior of boat--didn't mean to imply hull was wooden. Actually, its a 1984 Carter 35', fibreglass hull, with one of the first "inboard" swing keels now used in the Southerly line. (That keel box is also covered in teak.)
If anyone else has used CPES or MAX PCR or WoodEpox, would appreciate their views on whether it is better than thinned-down "high solids" epoxy.

[irwinsailor]

I have used Rit Rot several time to repair rotting area's. I have never been happy with the results. I found that I could cut the area out and replace with new wood in about the same amount of time and have a good repair that would last years.

[GordMay]

Gunnar probably used BoatLife "Git-Rot"
How to use GIT-ROT BoatLife - For the Life of Your Boat

[cat man do]

[quote=JeffHale]Thanks for inputs. Doesn't sound like most people have tried these "new" products, but those that did found them helpful. Mixed reviews on solvents (AKA thinners); maybe a chemist will know whether their evaporation leaves holes big enough for water to enter.
[quote]

The whole idea is that the thinned down epoxy soaks in better than the unmodified epoxy.

If there are any pinholes they get filled/covered with the next lot of unmodified coats/fiberglass.

Dave

[Kapena]

Really simple...you have the manufactor, who formulated the product, recommending not using thinner after conducting scientific testing or you have someone who has done no testing recommending using thinner.

It's your call.

[delmarrey]

Originally Posted by cat man do

When it came to glassing plywood, we found that after full cure we could peel the glass from the ply quite easily.

Adding 10% metho[denatured alcohol] to the mix, and coating the ply first, and then glassing we actually pulled timber veneers away from the ply, or the glass tore.

I came to the same results but using MEK. Thick epoxy just doesn't penetrate the wood enough to get a good grip.

Sometimes I use epoxy like paint to seal off wood edges and bottom sides to deck plates as well as other structural pieces where the wood needs to hold under stress.

I had a soft spot in the bilge where a wood bulkhead passes through. I coated it with a thinned epoxy and then later with full epoxy. In four years it has held up to the fresh water that makes it way down the inside of the mast. It still looks like the day I treated it. It works for me!...................._/)

[delmarrey]

Originally Posted by Kapena

Really simple...you have the manufactor, who formulated the product, recommending not using thinner after conducting scientific testing or you have someone who has done no testing recommending using thinner.

It's your call.

It's a disclaimer! If something goes wrong they don't want the blame. But they still tell you how to mix it and where and how to use it.

The probem being that epoxy treated wood rot is less flexable and will break before it bends vs the good wood. So one has to take in consideration where it's application is used. That's a decisson even an expert would shy away from if it doesn't belong to himself, the risk factor.

In a structural area, wood rot is bad news. It's best to cut it out and replace the bad wood. e.g. bowstems, transom corners and deck joints.