Paint: Water Based Epoxy

[SkiprJohn]

I bought a bunch of water based epoxy paint (Pittsburgh) at a yard sale a few years ago. I've recently started experimenting with it by painting the bottom of my dinghy. After a week it still picks up fiber from the carpet cushione dinghy dolly. I will try one more time to put a light coat on and give it more drying time but this paint might be something that folks may want to avoid for boat work due to its moisture holding characteristics.
Kind regards,
JohnL

[Talbot]

Perhaps that paint needed a catalyst !

[SkiprJohn]

Aloha Talbot,
Yes, I followed the instructions with a two part primer same company (Pittsburgh) and it does require a 1 to 1 catalyst which I studiously mixed and applied. As I said, I will try again but maybe will end up with a lot of two part epoxy paint for the interior if this doesn't work for anything else.
kind regards,
JohnL

[Chuck Baier]

John, When you say a few years ago, there is a good chance the catalyst has gone bad and is not kicking the paint.

[David M]

A lot of catalysts do have a shelf life.

[SkiprJohn]

Thanks guys. That might be it. I'll try some other cans of catalyst to see if there is a bit of difference.
Usually in my reference to a few years it means 10-15 years ago. Since I've used some paints older than 30 I never thought it'd be a problem.
Kind regards,
JohnL

[Boracay]

At risk of getting my year one chemistry wrong epoxy uses a hardener as opposed to a catalyst.

A catalyst speeds up a chemical reaction but is not consumed by it.See Catalysis. The most common marine form of catalysis is to increase greatly the rate at which polyester resin is cured.

I would disagree with the entry under Epoxy in Wikipedia. The hardener in the reaction is clearly "consumed" in that it links with the resin molecule(s) to create a solid mass.

If the mixed hardener and resin does not set possible causes might include :-
1) Too much hardener in the mix.
2) Too much resin in the mix
3) Temperature too low
4) Mix contaminated
5) Incorrect hardener used.

Try doing very small test batches with various proportions and see if any set when left in a warm place. Be careful as pots of mixed epoxy resin/hardener can catch fire "spontaneously".

[Alan Wheeler]

You are absolutely right on all accounts Boracay.
Skiprjohn, the only negative with water based Epoxy is the fact that the water has to escape to allow the hardening to take place. So ensure you have good temp and low humidity. The other issue with many of the old water based epoxies, was that they did not "fill" the "gaps" that the water left as it evaporated. So the paint can remain slightly porous. It took a few years to get that part sorted and I would say it only really came right about 8-10yrs ago. Of course, that may vary overseas than what products we were limited to in NZ back then. Now we can get most anything.

[SkiprJohn]

Aloha Alan,
Thanks. I'll try another coat and leave it out in the sun longer. Wish I could find a dry couple of days.
I'll keep folks posted.
JohnL

[hellosailor]

John, as "paints" have been replaced by "coatings" the old rules have gone out the window. Rustoleum red primer, unused in the "sealed" spray can? Two year shelf life, then they expect it to congeal and clog, even unused. A lot of stuff is "on the clock" now that it has become more than a mixture of oils and pigments.

Nice folks at Rustoleum, when I said "I didn't know that" they sent me a couple of free new cans, too!

[Alan Wheeler]

That's good product that Rustoleum. I just tried it and have been very pleased. I didn't realise they made paints other than just corrosion protectors.

[SkiprJohn]

I've got a bunch of marine rustoleum in cans and will be using it too. I find most my stuff at yard/tag sails and these came to me at $2 a pint. That's about beer price at some establishments. I hope it lasts much longer.
Kind regards,
JohnL

[edboat]

As a marine coatings rep, I'll say you get what you pay for. SkiprJohn, if the coating you applied has not cured, please don't put another coat on top of the existing coat.

[cat man do]

Seems they haven't got any better

Worked near a new tri build that used water based epoxy primers and topcoats, Primer took nearly a week before they could board it back and it was really disappointing the amount of work they put into prep only to then use waterbased topcoat and hours later watching the bugs walking around dragging their ass through the finish.

Ended up sanding it back and using a solvent based topcoat.

Dave

[SkiprJohn]

Aloha Ed and Cat,
This isn't sounding hopeful is it? Oh well, as I said, it is an experiment and never really too surprised when my experiments don't turn out as I'd hoped. There are several other places I can use the two part water based paint which are not so critical.
Kind regards,
JohnL