Rain on Uncured Epoxy

[tomlarkin]

I spent yesterday fitting and cutting out the first layer of my pilothouse roof. It's a 5 x 10 foot sheet of1/4-inch Okoume plywood. Around 9:00 last night I lay it on sawhorses in the back yard and coated it with a nice thick coat of white-tinted epoxy.

It rained last night (in Seattle? Shocking.). The epoxy is is all gummy and bumpy. Will it ever cure, or do I need to call Edensaw and order a new sheet?

Any suggestions?

[Saltiguy]

I've had the same experience many times and found that some time in the sun will do the job.
BTW - what do you use for white pigment?

[tomlarkin]

It's sitting in the sun now. We'll see. This is just an interior coating for the cabin top overhead, so integrity isn't too much of a concern.

I use the West System pigments. They're pricy, but work well, and they're formulated to work with epoxy. I know other pigments work, but am nervous about what they do to the long-term integrity of the finish.

I really like coloring the epoxy. You get a much more accurate feeling for what the finish is because your eye isn't distracted by the wood texture.

[Todd Bradshaw]

One of the Gougeon techs told me once that rain can wash the hardener out of uncured epoxy - which doesn't sound good.....

[Richard Smith]

Sounds like a good time for a little friendly "predicting" - wagering? Will it cure or not?

I've taken a clump of West that I have thickened really well and used it to glue rocks together in while under salt water in a marine aquarium. It hardened just fine. But, something DOES leave the epoxy because the protein skimmer goes nuts - probably the amines.

My bet: I'm going to say that unless it was really fresh, that it will cure just fine. No predictions on spots, though.

[carioca1232001]

I've had the same experience many times and found that some time in the sun will do the job.
BTW - what do you use for white pigment?

I´ve seen an otherwise first-class job of an epoxy+dynel solution on a show-case mahogany deck go sour after it was drenched with rain.

You could still see the mahogany substrate and white-wood (marfim) pin stripes beneath the horrid milky mess that was visible on the surface.

So I stripped the lot and while redoing it in a hurry, didn´t mix the epoxy + hardener as well as it shoud have. Some of the dynel felt moist and lifted off with minimum effort...... and there were white patches underneath the dynel.

The weather came to my rescue though. A sunny spell for 5 days left me with a clean slate, thank heavens !

[onobleboat]

Depends on what stage of cure the epoxy was in before it rained, epoxy cures from the inside out (kinda ) it makes it's own heat, looks like a wait and see, it you can sand it in a few days and it makes dust, the inside is just fine, outside finish might have to be recoated, play it by ear

[paladin]

forget the ears...use the eyes to determine the quality.....

[boatbear]

I would be very tempted to sharpen up a couple of cabinet scrapers and strip it all off. It won't take long at all if it is still gummy and you will be really happy with the next coat.

And hey, what were you thinking - leaving it exposed in Seattle. Even here on the other side of the planet Seattle is legendary for rain. Envied, in fact.

[tomlarkin]

And hey, what were you thinking - leaving it exposed in Seattle.

A month without rain made me think I was in California, I guess. It's rained and sprinkled all day, so the epoxy didn't get any sun. It does seem a bit less tacky though...

I'll update either way tomorrow.

[Saltiguy]

I'm in Florida and it rains every afternoon in the summer months, so I've had my epoxy get wet a number of times. It has always kicked-off OK after a delay of up to 24 hours.

I've never tried the West color additive. I use aluminum powder that is sold to signpainters to mix silver paint. Just a little in the epoxy and you're opaque in 2 coats. Sands nice too.

[Bob Perkins]

Heat cures epoxy. It just needs to be warm. Uncured epoxy is almost always because of improper ratio of mix or not mixed well enough. You can't overmix epoxy - only undermix it..

[carioca1232001]

Heat cures epoxy. It just needs to be warm. Uncured epoxy is almost always because of improper ratio of mix or not mixed well enough. You can't overmix epoxy - only undermix it..

Well said.

'Ten on Ten' !

[JimConlin]

One of the Gougeon techs told me once that rain can wash the hardener out of uncured epoxy - which doesn't sound good.....

The WEST hardeners are water-soluble, so this might be possible. If it hasn't cured in a day or so, get some rags and several gallons of solvent.

[tomlarkin]

It's starting to harden OK now. I bet by tomorrow it'll be ready to sand. I dropped it in place on top of the boat, and it looks really nice.

... rain can wash the hardener out of uncured epoxy

I'm not too worried about this - it was a light rain and there wasn't much runoff from the piece.

[tomlarkin]

Hey, here's the piece, mounted in place temporarily. I'll put some lights inside tonight to keep it nice and warm. It looks nice up there - kind of a 'wet look'.

[Bob Triggs]

Something that I have found helpful when working outdoors is the use of cellophane or food wrapping plastic; gently layed over the epoxy coating. You can use clothespins, thumb tacks, spring clamps etc to secure. This will shed moisture from light rain and mist, fog and heavy dew etc. Once the epoxy is cured the cellophane is easily lifted from the surface.

This temporary plastic protection is best used on base coats of epoxy or earlier work, not for final finish work- unless you can ensure a very light application of the plastic sheeting with no damage to the coating that final sanding etc can not reduce.

As far as I can tell there is no residue left from this protective layer of food grade plastic wrap that would interfere with successive epoxy aplications or curing.

[Saltiguy]

Funny, I had it happen again last night. Late in the afternoon I roller-coated 4 4x8 sheets of ply with West 205/207. The sheets were on horses, under a tent. It rained hard last night, and in the morning the sheets were still tacky. The epoxy that was left in the roller tray was rock hard, and clear. The sheets stayed out all day today - (Florida - 80 degrees and VERY humid) and the sheets are better, but not sandable. Tomorrow they will be OK. I've had it happen before.

[tomlarkin]

Just to close this thread, the epoxy never did set up, even after 3 days in the sun. I had to scrape it off. It was difficult too, very gummy and sticky after all that time in the sun. Once I had the gummy part off, it left a nice sandable layer that seemed completely cured. I sanded and recoated. It looks great. I'll be installing it this Sunday.