System Three varnish over "clear coat" epoxy

[Charles Neuman]

I am using System Three's clear coat epoxy as a base for their varnish. When I received the varnish, it said I had to wait 14 days for the epoxy to cure completely. I do not have 14 days to wait, so I'm stuck.

I had done my homework and read the Epoxy Book. The requirement to wait 14 days is not in the epoxy book. System Three tells me that this is because the epoxy book was written before they had the varnish. I feel their literature is misleading, because I received their epoxy book along with their catalog, which has their varnish in it. They should have included an insert in their epoxy book, especially since they warn you to read the epoxy book before calling tech support. [Note: Please see below for some interesting responses I got from tech support.]

In any event, I am now faced with a tough situation. I do not have two weeks to wait for my epoxy to cure. Any suggestions on what to do?

1) Varnish over the epoxy anyway. Anyone know what the results would be?

2) Maybe just wait one week instead of two weeks. Any guesses on possible consequences?

3) Try to speed up the cure of the epoxy by using heat.

4) Sand the epoxy off and start with bare wood.

If you can help, I would greatly appreciate it.

Thanks,

Charles

[ 09-12-2003, 02:05 PM: Message edited by: Charles Neuman ]

[gary porter]

Charles, Are you varnishing just the insides?
You could apply a thin coat of sys III regular epoxy which will give you good protection and then varnish at some point in time later. I've done this for as much as a year then sand the epoxy lightly just as you would when renewing varnish and then apply with your varnish. I assume you have talked to Sys III tech support on the matter?
They are usually very helpful. If you are in a hurry to get in the water I'd just forgo the varnish for now as one coat won't do anyway so that in itself takes some time.
Gary

[Charles Neuman]

That's a good idea to put a layer of regular epoxy over it, if I have to wait. They say that clear coat epoxy could get water stained, so that is not really a good outer coat, but regular epoxy might be.

I'm curious: If you can get a good smooth shiny layer of epoxy as your outer coat, what did the varnish add to the looks of your boat, other than maybe a slightly amber tint?

I agree the folks at System Three are helpful. I'm in the middle of phone tag over this issue. I was curious if anyone has experienced varnishing before the 14 days are up. The System Three folks said that the concern was that if the epoxy has not cured completely, there may be chemicals left that could interfere with the varnish. OK, so how bad would it be, and what would the consequences be? That's what I'm curious about. "Not recommended" might be different than "would be a disaster".

Charles

[gary porter]

Originally posted by Charles Neuman:
That's a good idea to put a layer of regular epoxy over it, if I have to wait. They say that clear coat epoxy could get water stained, so that is not really a good outer coat, but regular epoxy might be.

I'm curious: If you can get a good smooth shiny layer of epoxy as your outer coat, what did the varnish add to the looks of your boat, other than maybe a slightly amber tint?

disaster".

CharlesCharles, the varnish will give you UV protection and the epoxy will not on its own hold up under uv for too long. You will get a blush after a while but that will clean up when your ready to varnish.

Not sure about the effects of the epoxy not being cured yet but it would probably cause the varnish to not cure well and or remain somewhat soft. That would not be a desireable result. I've found the folks at Sytem III to be somewhat conservative and it may work better than they say. Still I'd just go with the epoxy for a while and then varnish. The regular epoxy will give you a fairly good looking finish for a bit.
Gary

[NormMessinger]

Try a little patch, if the varnish cures pretty well, say over night, you are good to go.

Any varnish might react the same over partly cured epoxy so it isn't just the System Three stuff. Maybe it will cure may it wont. Try it and see. My bet is it will.

[Charles Neuman]

I've got a patch of epoxy ready for a varnish test. So if it cures, it cures, and everything is AOK? I was wondering if there might be problems later on down the road. It all seems like black magic to me.

I could probably wait a week, and I might heat the room the boat is in, so that should help cure things a bit faster.

Charles

[JimConlin]

It's a happy thing that both products are from the same vendor. Ask the vendor. Ask particularly what treatment of the epoxy, like heat, might expedite the cure.

[NormMessinger]

I don't think there will be any problems down the road if you put the varnish on "early" and it cures.

However, no point playing telephone tage with System Three. Send 'em an email. I did that quite a few times a while back and almost always got a reply the same day. I recently called with a question and got the answering machine, the all our reps are busy, thing. I whined cause I wanted the answer right away. About an hour later I got a call back, from somewhere in Pennsylvania. Seems they were all traveling.

[Charles Neuman]

Maybe this isn't such a big deal after all. I used a piece of marine plywood, put some clear coat epoxy on it, waited 24 hours (temperature was about 75 degrees F), coated it with varnish, and 12 hours later the varnish seems dry. And my plan is to wait several days.

[NormMessinger]

Right!

On the other hand if I were painting over System Three slow cure with Kirby's paint I would very likely have to wait two weeks. Don't ask me how I know I don't want to talk about it.

[Charles Neuman]

I tried both phone and email tech support, and I got two different responses. Both were helpful, and if I combine the results I'll be fine.

1) One response said that if the epoxy cures to the point that it can be "powder sanded", then I can varnish and everything will be fine. I assume "powder sanded" means that the epoxy won't gum up the sand paper.

2) Another response said that I can speed up the process as follows: To neutralize any risidual curing agent on the surface, I should wipe the surface with vinegar, then wash it off with soap and water and let it dry. Then I can sand and varnish.

So that's pretty helpful info.

[ 09-12-2003, 02:11 PM: Message edited by: Charles Neuman ]

[Charles Neuman]

I asked the guy who gave answer #1 above about answer #2. He said there is nothing to "neutralize". I'm not sure if he meant for all epoxies or just for Clear Coat, which is what I am using. Furthermore, since Clear Coat epoxy does not produce amine blush, no wiping of any kind is necessary.

In other words, we are back to what the Epoxy Book seems to say: If you can sand it, then for all boatbuilding purposes the epoxy can be considered cured.

More importantly, I sanded and varnished, and 24 hours later the varnish is dry (and looking mighty nice, I might add). So I didn't need to be so concerned about the 14 day warning that is on the can of varnish.

[SailBoatDude]

In 24 hours your epoxy will be dry, even sandable, but not cured. This is the crux of their problem, wanting their products to be cured before the next steps. The epoxy may move a bit during this full curing time and place unwanted marks in the finish. This will be most evident in corners and hard inside turns where the epoxy may pool or be thicker then the rest of the coating. Having just finished a boat where epoxy was used before varnish was put down, you want to let the stuff cure before you finish her out. If you don't you'll end up using a cabinet scraper to get the goo off and wait for a suitable time to recoat with finish, if you haven't dicked up the epoxy coating bad enough to go back there before the finish can go on.

[Charles Neuman]

Hmm, that's pretty interesting. I'll see how it goes.

This is slightly off-topic, but let me ask: My first two coats of Clear Coat epoxy produced a pretty scratchy surface, almost like sandpaper. It wasn't air bubbles. Just regular little bumps. Maybe the epoxy built up on little splinters of wood or something. I hadn't sanded the marine plywood especially well, so I think that contributed (it didn't happen on smooth surfaces of solid wood). Is this normal?

I'm on my second coat of varnish, and from all the sanding I have done it's not noticeable anymore, but I was just curious.

Also, are there any books on finishing that include epoxy coating? I assume most books are more traditional.

[thomas cashman]

Arch davis recommends painting over clearcoat he may have some experience with this problem. Arch davis designs

[Frank Wentzel]

Charles

Yes the "barbed wire" effect is sanding dust and small fibers of the wood that have become petrified by the epoxy. I usually do only a cursory job of sanding before the first coat of epoxy or, more often, CPES. Then after the epoxy cures I resand to get a smooth surface before recoating. I think it cuts down sanding time and because the surface is now waterproof I can wash the surface with very dilute detergent and water to thoroughly remove all the sanding dust (or even wet-sand).

You don't say if your boat is inside. If it is I would try to raise the temperature about 20 degrees or so for a few days. Theoretically the curing process will double in speed for every 18 degrees Fahrenheit rise in temperature. Also, if some of the problem is evaporation of solvents, you will get an even greater beneficial effect from the rise in temperature. To make it easier to raise the temperature you could also put a plastic "curtain" around the boat so you don't have to heat the whole room. As others have indicated, it may not be really necessary to completely cure the epoxy before you varnish. But if you can heat the boat for a few days without too much trouble, it may be worth the effort if only for your peace of mind.

/// Frank ///