Help, Epoxy isn't curing!

[Tim B]

Hi all,

I'm covering a small boat with 4 oz Eglass and MAAS epoxy Resin and Slow Hardener. The cloth was laid down over the hull and the epoxy-hardner mix poured on and spread with a foam brush. I was mixing the epoxy in 16 oz cups, about 12 oz at a time using the metering pumps provided. Covering the boat took about 16 cups full. There is one area of the hull where the epoxy did not cure. The rest of it has cured fine with no blush. I put the epoxy on last night, the good areas where cured this AM.

The problem area is sticky to the touch and cloudy looking. The area roughly corresponded to a cup full that I thought I might have missed a stroke on the resin pump. Therefore I tried mixing up a partial cup that had an extra pump full of resin and applied it to the sticky area. That was mid afternoon. It hasn't helped, maybe looks cloudier.

Any advice?

[Charlie J]

obviously the mix wasn't correct in that area.

I'd scrape as much of the sticky stuff off as I could get using a squeegee so you don't destroy the glass. Then I'd recoat with a correctly mixed and stirred batch. Hopefully that'll do the job. Otherwise, you'll probably have to cut out the glass in the uncured area, wash the hull down with lacquer thinner (or acetone) and reglass.

I once glassed a 6 foot long section of deck with epoxy with no hardener in it at all redface.gif . It's not hard to goof up when you are doing stuff like that.

[Ross Faneuf]

I've also had a screwup like this from forgetting to mix the epoxy; hard to believe, maybe, but more than possible doing this kind of job. Solution is the same, unfortunately - but it's not as hard as you might think.

I also had a batch fail because I tried to beat cold weather, and the epoxy sort of froze on the job. 2 days later I was able to just pull the cloth off.

[Scott Rosen]

The problem would be too much resin, not too little resin. Before you do anything drastic, try brushing a coat of the hardener over the sticky spots. Give it another couple of days. The extra hardener might do the trick.

[Tomcat]

If it is reasonably liquid the brush on technique might work, but I worry about it just curing on the surface. If that seems a likelyhood, I would just wash it off with acetone, and then recoat, of necesary you may need to sand the cloth off at the cured edges then recoat with a patch, which should fair in well.

West for instance in mix sensitive, so even if you flash off the uncured resin, it may not be in good shape.

[Leigh]

Have you tried heat lamps? I've had an epoxy repair cure very nicely in winter using heat lamps. The unused left-over mix took a day to cure without the heat lamps. If theres some hardener in the mix, maybe it just needs some temp to help it along.

[John E Hardiman]

I may well be too late coming into this, but with the flukey weather we have had this year up in the Pac NW my first suggestion would be wait at least 72 hours. I was using System 3 with slow hardener and it was easily taking 48 hrs to get to "thumbnail" stage this summer up here once it was spread thin. I concur with the heat idea, but just don't burn it.

[bainbridgeisland]

I don't think you should even try to save the uncured spot. Just take a razor blade and cut it out. Re-prep the surface and re-glass. You may have trouble for years to come if the epoxy does not cure right. Why take the risk to avoid a few hours work?

[Keith Wilson]

Assuming the proportions aren't right, (and I'd be wiling to bet a lot that they aren't) it could just as easily be too much hardner as too little. Once all the resin has reacted, the excess hardener just sits there, making the mix pretty useless. In fact, a slight excess of rsin will self-polymerize eventually. I'd cut it out and scrape it off, if I were you. I once did the entire bottom of a 12' boat with a very carefully measured 2:1 mixture of System 3 resin and System 3 resin. :rolleyes: Fortunately it was the third coat just to fill the weave of the glass, and I could just wipe it off with solvent.

[thechemist]

Anything off-ratio may "cure", meaning get "not-wet", but will have mechanical properties unlike what they are supposed to be for properly mixed, properly cured material. I recommend removal.

[NormMessinger]

So, it is decided then. Cut out the uncured section and wash off the uncured resin that has soaked into the wood as best you can. Acetone or MEK works. (Hey, it's your life.) No vinegar cause you may not be able to get it all rinsed off.

--Norm

[Tim B]

Thanks for all the advice. I guess an update is in order to close out the post. My first conclusion was that there was not enough hardner in the mix. I therefore mixed a small batch that was heavy on the hardner side and applied this. No change.

Finally, I ended up scraping all of the epoxy off that I could get. I left the cloth intact and therefore did not clean it off to bare wood again. I mixed up a new batch and applied it and it appears to have cured fine.

Thinking about the process I used, I conclude that the failure was caused by not mixing the resin & hardner sufficiently. The 'bad' mix of epoxy covered about a 4ft by 6 ft section of the hull. About 1/2 of that area cured fine. The problem areas were spread throughout the section.

I need to add another filler layer or two to bring the epoxy up to the thickness of the areas around this one. I'll check carefully again for any adhesion problems, real or potential. Thanks for all the advice.
tim

[mariner2k]

Remove the uncured stuff. mek or laquer thinner worked for me. ( and elbow grease, bronze wool,plastic scrubby) Then make sure your ratio is right on and mix extremely well. It'll work then.
mariner