CPES Penetrating epoxy...

[No Mas Films]

Has anyone tried the Smith Co. CPES penetrating epoxy for use under paint or varnish? I cant see using Mas or West under varnish, but this stuff seems to make sense... Thanks, Chris

[Figment]

I've had great success with it when using polyurethane-based varnishes.

I've seen cases where traditional oil-based varnishes were not so successful. I suspect that this is because the CPES prevents the varnish from penetrating the wood as it would ordinarily, but it could just as well have been applicator error.

Either way, I think it's prudent to let the CPES cure at least twice as long as recommended before proceeding with varnish.

[rescuesailor]

I have become a big fan of CPES. As a trail I used on the frame of my forward hatch. I then applied 5 coats of Epifanes varnish over it. After being in the yard with no protection for the last year and a half the hatch looks as good as it did the day I finished it. I might add that I live in the Texas Gulf Coast where weather, sun, and airborne contaminates are harsh. I have since started to use it where ever I have wood on the boat, including soaking wood blocks to use as a recore material. I am currently using it the floors in my boat prior to painting. Outside of the price I love it!

[No Mas Films]

Well, I tried the cold weather formula today for the first time. The stuff may well turn out to be a wonder drug! By far the thinest epoxy I've ever seen ( normally I use Mas) and the wood drinks it up like alcohol. After you use it once, you start looking for other places to apply it. LOOK OUT WOOD!!!! Now, I hope the stuff hardens...

[No Mas Films]

BTW, I'd love to try this experiment when I get a chance; Paint on CPES on ground or sanded fiberglass, then after the solvents evaporate and the epoxy is gummy, use MAS to glue something to it. Could be the ultimate bonding experience! :-)

[keelbolts]

How does CPES differ from Git-Rot? I've thinned epoxy w/ acetone with fine results. As for varnish failing over epoxy: Figment, did you wash the amine blush off before varnishing?

[No Mas Films]

I have no idea how it differs. Does Git-Rot cure in 45 degree weather?

[keelbolts]

I'm not aware of an epoxy that cures at temps that low. However, I have used a 100 watt bulb to warm both the epoxy & the area to be glued with success. The good thing about glueing at low temps is that, according to the the folks at West System, the joint is not weakened by the cold it just takes longer to set.

[Figment]

As for varnish failing over epoxy: Figment, did you wash the amine blush off before varnishing?

Yup, that's the "applicator error" I was referring to. I don't think they let the CPES cure completely before going with the varnish, and the amines popped the finish.

IIRC, system three's fast hardener will work down to 40 degrees. It's hardly a "penetrating" resin at that point, however. Molasses.

[No Mas Films]

CPES cold system claims to cure in as little as 4 days @ 32 deg. Take that, Git-Rot!

[No Mas Films]

I noticed you are thinning epoxy with acetone. I have no idea what solvents are used in CPES, but they sure smell strong! I almost never use acetone around fiberglass though. I have a stupid theory that acetone will melt alot of different surface impurities, dusts and previous coatings, thereby sealing the fiberglass from the epoxy you are counting on to make a mechanical connection with. I wipe down with denatured alcohol instead. Am I nuts?

[Tim]

I have a stupid theory that acetone will melt alot of different surface impurities, dusts and previous coatings, thereby sealing the fiberglass from the epoxy you are counting on to make a mechanical connection with. I wipe down with denatured alcohol instead. Am I nuts?

No, you're not nuts, and if you prefer alcohol that's fine. There's nothing wrong with wiping down with paint thinner, either. Acetone is the universal solvent for fiberglass resins (all types), but a wipedown doesn't affect the cured surface. Acetone is not nearly the melt-all substance so many think it is. It is a strong solvent, but it doesn't affect everything. And the super-fast evaporation rate means that no excess solvent remains on the surface, so the contact time from a wipedown is extremely short. The quick evaporation and cleanliness of the solvent itself is one reason why I prefer acetone wipedowns in many situations. I use it almost exclusively for raw fiberglass and new work.

That said, I wouldn't submerge a fiberglass molding in a bath of acetone and let it sit for weeks, but that's pretty far removed from a wipedown. Many paints do not hold up to acetone either, so if you're wiping a painted surface, there's a real possibility of affecting that old finish. Note that Awlgrip is extremely acetone-resistant and is not affected by this solvent, but many "regular" paints are.

Any wipedown brings the possibility of cross contamination, so it's best that the surface be vacuumed or blown down before solvent wash to remove as much of the dust as possible, and to keep using clean areas of your rag as needed.

[rescuesailor]

I noticed some comments about amine blush with CPES. While I have always washed down my projects between coats I have never noticed anything that looked like amine blush after using CPES. I don't beleive I noticed anything in the literature about it either. However that does not mean its not there. My question would be if the product is not fully cured would it not allow for the chemical bonding of similar products, IE West systems epoxy? Any comments or experience on this?

[Bob]

I have just learned of CPES. I have an old varnished oak front door which needs stripping and refinishing. It's yellowed and black. I was going, am going, yo use 5f5 remover then varnish. What about sealing w/ CPES then varnishing w/ polyurethane or Epifannes? I like the idea of sealing with an epoxy product first. I do have some concern about using epoxy with the oak. A valid concern or not?
I also have a thin rosewood ply lamminate for my cabin sole. Originally varnished, I suspect, but needs refinishing. Again what about sealing w/ cpes then varninshing with a hard polyurethane rather then the presumably softer Epifannes.

[Hirilondë]

I'm not convinced CPES, Bristol Finish or any other 2 part material is worth using at all. The whole point for using them would be to reduce how often you have to give attention to the finish. I think the only way to maintain beautiful clear finish on wood is constant attention. Bulkheads, cabinetry and other interior surfaces can go years without attention but cabin soles and anything exterior can't. And should the time come, err, when the time comes to remove the material for a fresh start nothing strips as easily as plain old varnish.

[Tim]

I'm not convinced CPES, Bristol Finish or any other 2 part material is worth using at all. The whole point for using them would be to reduce how often you have to give attention to the finish. I think the only way to maintain beautiful clear finish on wood is constant attention. Bulkheads, cabinetry and other interior surfaces can go years without attention but cabin soles and anything exterior can't. And should the time come, err, when the time comes to remove the material for a fresh start nothing strips as easily as plain old varnish.

I couldn't agree more. Only good maintenance truly extends the life of any finish. I just don't get this overwhelming desire so many people seem to have to "pertify" their wood in a mass of epoxy. Wood is wood, and holds up nicely on its own--as long as you don't neglect the necessary maintenance.

And if you neglect it, nothing is going to help in the end.

[Rachel]

I'll third that! I have nothing against epoxy for many uses, but let's let wood's good qualities shine through and not "petrify" it every time.

R.

[Tim Mertinooke]

I would like to take the CPES thing in a different direction. I recently removed my 45 year old rudder which was encapsulated with polyester resin and one layer of cloth some time ago. The previous owner from whom I bought the boat purchased her in 1974 and told me the rudder had already been encapsulated at the time of purchase. The rudder is made of mahogany and is in remarkable shape. No rot, structurally solid, not warped, tight, no corrosion on the shafts, etc. The joke on the Ariel forum is, "what varnish are you going to use before splashtime." Right now the rudder is in my house and has been for a couple weeks and is completely dry. I am considering coating it with CPES until it takes no more, then encapsulating with west and one layer of cloth. Should I leave well enough alone and just put it back on as bare mahogany like it was when it left the factory or should I go forward with my idea of CPES, then west and cloth. A true encasulation is a pipe dream I know, but this could be a close second. Has anyone tried this product on something that will be submerged like a rudder? Will West System chemically combine with CPES if coated quick enough?

Before


After

[Hirilondë]

From the picture it looks great. I would paint it (a good oil primer then bottom paint) and put it back on.

[Tim]

Definitely just paint it. You'll only hurt it in the long run if you try to "improve" it.

Remember: there are lots of boats out there made ONLY of wood, and they're not coated/soaked/encapsulated with epoxy.

Wood works. Don't mess with good wood.

[Tim Mertinooke]

Paint it I will. Thanks gentlemen.

Dave, what type of oil primer would you recommend for mahogany?

[Hirilondë]

There are a couple routes you can go for primer:

1. The modern route would be Awlgrip 545 epoxy primer then bottom paint. This works quite well. I like 545 for many applications, it is tough stuff.

2. A couple of primers were used on wooden boats back in the day. Seeing as your rudder is a carry-over from wooden boats during the transition to building glass boats using an old traditional bottom primer is certainly appropriate. Red lead primer would be my choice. It is a resilient semi-hard paint that sticks well to wood. bonds well to other paints, has a fungicide (by default, the lead itself) and works well to protect your bronze also. We use Kirby red lead primer and white lead paste on our wooden boats regularly.
http://www.kirbypaint.com/products/