CPES gone bad

[mshipman]

A couple of years ago I put a few coats of CPES on my mahogany boat with the intent of coating with 5 year clear. The 5 year never was applied and my boat eventually was exposed to the elements in Florida. Lots of rain (2 hurricanes) lots of sun etc.

The CPES pretty much washed off, there are places where it is still visible though.

Here's my question: Is it necessary that I sand down to bare wood, or I can I just rough it up enough to smooth out the raised grain and re-apply? I am most concerned with the finished look. I remember that when I applied the CPES it darkened the wood considerably. If I sand down enough to smooth out the raised grain, will re-applying the CPES cover/camoflage the areas of the wood that are gray and discolored or does the mahogany need to be consistent in appearance?

It's A LOT of sanding, but I don't want to end up with a boat that looks like junk.

[Keith Wilson]

CPES was never intended to protect wood from the elements. If you have weathered and discolored mahogany, just putting on more CPES won't fix the damage. To make the color even under a clear finish, you'll have to sand and perhaps bleach out the discolored areas. You could also use paint. CPES is good at extending the useful life of varnish or paint, but it doesn't really do anything by itself.

[Concordia..41]

Rule 1: Never cut corners with varnish/clear coat/shellac/high-gloss paint and/or anything of the sort. When you apply the coating it will amplify any inconsistancies in the prep.

While CPES has many applications, as part of the Five Year Clear system it has specific time frames for application between coats. PLEASE sand down to bare and uniform wood and follow all instructions for reapplication of the CPES and Five Year Clear.

If you have any questions, call the # on the can. The folks in California will talk you through the process. Often Steve Smith himself answers the phone.

Rule 2: You'll never regret doing things right ;)

- M

[mshipman]

Originally posted by Concordia..41:
Rule 1: Never cut corners with varnish/clear coat/shellac/high-gloss paint and/or anything of the sort. When you apply the coating it will amplify any inconsistancies in the prep.

While CPES has many applications, as part of the Five Year Clear system it has specific time frames for application between coats. PLEASE sand down to bare and uniform wood and follow all instructions for reapplication of the CPES and Five Year Clear.

If you have any questions, call the # on the can. The folks in California will talk you through the process. Often Steve Smith himself answers the phone.

Rule 2: You'll never regret doing things right ;)

- M

[mshipman]

Thanks, your right about doing things right. You would be amazed at the crap that gets EVERYWHERE from a hurricane, be it boat, car, house...

[paul oman]

The CPES is approx 70% solvent, which evaporates away - thus you were really only putting on 30% of what you thought you were applying (albeit the solvents do help the 30% epoxy part to penetrate into the wood).

You will need to sand the wood back down to a uniform color - or try wood bleach (sold at home depot, etc - heck even regular bleach might work too!) to get it back to a even color.

Best final fix would be a solvent thinned epoxy (thinned maybe 25% or 30%), then epoxy without solvents followed by several coats of varnish or 2 part clear urethane with UV blockers (which can also go over the varnish!).

cheers

paul oman
progressive epoxy polymers

[Wild Wassa]

This is not a CPES gone bad story but certainly CPES being surprisingly inconvenient. Just a few observations and they only concern the aging/curing of a racing quality surface.

Polyurethane over epoxy over CPES takes a long time for the surface to settle down, compared to a Poly over an TPRDA/epoxy surface. I'm finding this with a few different timbers now (Douglas is the main timber that I coat). I've compared the quality of the finished surface on different timbers, with and without CPES.

CPES stays very flexible and is drawn into the timber over a long period of time, finding every weakness in the timber surface. I find the top coats chase the CPES in lessening the quality of a hull's racing surface (paint-wise and drag) even after many coats and fairings. This must be a plus for the timber, as the shrink wrapping is extreme, and :cool: , but CPES doesn't suit my normal hard slick finish, I'm finding. It is causing a good deal of extra work in fairing. On a few foils and a boat I've put on one side (for comparison), TPRDA and on the other side CPES. The CPES sides are looking very ordinary.

I'm rethinking the use of CPES as an overall foundation below a smooth surface. For just over one year I've enjoyed using CPES and I'm starting to feel disappointed in what I expected as a stable foundation (but not at all disappointed in the rot stopping of CPES) when using it as a multiprimer (it is called Multiprime). For topsides (excluding the hull) CPES still appears adequate for general purposes but under a fine surface it is a waste of time (I'm now finding).

If you have any findings please add them. I don't want to stop using CPES it is far too valuable as a rot-buster but I feel it is just creating a lot of extra work. It is taking much longer to achieve a slick finish when I use CPES compared to a finish over TPRDA.

In future I'm going to glass macro directly over the CPES rather than apply normal epoxy over CPES prior to macroing, similar to the first epoxy/macro coating one applies to a foam core. Again any findings concerning a fine finish over CPES?

Warren.

[ 11-25-2004, 01:36 PM: Message edited by: Wild Wassa ]