Paint/primer over epoxy

[Whidbey Wherry]

I am building a Pygmy Boats wherry using System Three epoxy. I plan to paint the outside of the hull because of some serious mistakes made at the stem. They, of course, recommend their primer and paint, which is expensive and is a 2part poly. I have read in the forum of Kirby Paints and Interlux Brightside, but I am not sure of what primer would be best to use with these paints. System Three has some issues with "ordinary" marine paints.

[Whidbey Wherry]

I was going to send a photo of the boat, but I can't figure out how to do it. The FAQ does not have the instructions.

How do we do that?

[paladin]

You might just give Kirby's a call and ask...takes two minutes...but...I've used a lot of system three over the last 35 years and Kirby's does not need a primer..just scour the epoxy with 110-200 grit paper and apply..

[Jim Mathieson]

Don't forget to clean for possible blush first with water and scouring pad.
That wax ,if present will ruin everything.

[almeyer]

I used System Three on my boat, with two coats of Clear Coat as a sealer. The outside was painted, and I varnished the interior. Clear Coat is not supposed to blush, but it's a good idea to wash it down just to be on the safe side. I prepared the epoxy by sanding down with 220 grit sandpaper to give the surface a "tooth". For the exterior I used two coats of primer and two coats of topsides paint, both West Marine house brand - it was on sale at the time. Since the boat lives on a trailer, I didn't worry about bottom coating or anti-fouling. Works fine.
Al

[Bruce Hooke]

A couple of years ago I talked to someone from Kirby paints about using their paint over epoxy, and as I recall their answer was along the lines of "it should work but test it first because we have occassionally heard of people having problems with the paint not drying."

There are advantages and disadvantages to two-part paints such as what System 3 recommended. The advantage is that these paints are very tough and will, with reasonable care, last for a number of seasons, especially on a boat that is kept on land, under cover, when it is not being used. This additional lifespan relative to traditional marine paints may well make the 2-part paint cheaper in the long run. On the other hand, 2-part paints are very high gloss, which is right for some boats and not for others. This is a matter of taste. However, the high gloss also makes these paints very demanding to apply well. Little mistakes that would be less noticeable in a lower gloss paint, like dragging the brush back into an area that has already started to skin over a little, will jump right out at you with a 2-part paint, especially in the darker colors.

[Thorne]

I think the real question is -- do you need to prime over epoxy?

From my experience (somewhat limited) and reading a number of posts here, the answer is "No". Good marine paints should adhere to epoxy very well, better if it has been scrubbed/washed to remove any "blush" and lightly sanded to provide "tooth".

I used a marine high-build primer over CPES on my old fir hull, mostly to cover up / partially fill some of the irregularities, lumps, bumps, nicks, etc. It was partially successful, but not necessary, as the paint would have stuck to the CPES just fine. At the end of the day, I would have been better off using more epoxy fairing compound (I use Smith's) and skipping the primer.

Again from reading posts here about painting: raw wood requires primer or CPES, but CPES or epoxy just needs to be wax/blush-free and maybe lightly sanded.

Varnish on raw wood needs to be laid over a sealer, which can be CPES or thinned varnish -- the former comes highly recommended by many experienced forumites.

[ 03-24-2006, 09:42 AM: Message edited by: Thorne ]

[Whidbey Wherry]

Thorne: This is the first boat I have ever built. What is CPES?

No one answered my question about posting photographs. How is that done?

Jerry

[Wild Wassa]

CPES is Clear Penetrating Epoxy Sealant. It is made by Smith and Co. in the US. Considering it is an epoxy, it is not much thicker than water.

CPES comes in two equal parts, parts A and B. When mixing equal parts of A and B to make the working solution you will smell ... bananas blanched in acetone.

CPES is temperature dependent when curing, as it is 70% solvents. CPES is not for spraying as the solvents need to arrive at the same saturation within the medium as they are when first mixed.

Wood finds CPES very delicious ... end grain finds CPES even more delicious and is insatiable. Saturate the wood with CPES (if your bank manager gives you the Ok to do so).

Varnish sticks to semi-cured CPES like the proverbial, 'shi-t to a blanket'. In cold weather allow 8 days for the solvents to disipate to gain greater longevity with your painted top coats. As per the excellent data sheets that come with CPES.

CPES is an over indulgence on new wood but a god-send for use on old, dry or rotting timbers. CPES should only be applied to previously painted timbers after 97% of the old paint has been removed.

Timber that has been exposed to the elements, needs to be bleached before applying CPES ... if the timber is to remain bright. CPES will send old timber black(ish), and can be a big disappointment when applied to old timber if the original timber colour remains important.

CPES is good gear ... and is the real deal for restorations.

The Australian distributor is Senseal in Melbourne.

Warren.

[ 03-25-2006, 04:25 AM: Message edited by: Wild Wassa ]