Applying Gelcoat

[Hibbertdl]

So I bought a pint can of gelcoat a few years ago to cover some damage to my hull. Nothing major, just where the gelcoat chipped off and exposed the raw fiberglass. Worked pretty well. Took out that can today to do a little more. Poured a half cup & added several drops of the supplied hardener. Applied it with brush - but after 12 hours, neither the leftover in the cup, nor the layer I applied to my boat, had dried/hardened. Soooo...will it harden, eventually? ( not enough hardener). Or, if the can was on the shelf too long, and it doesn't harden, what's the best way to remove it?

 

[tpenfield]

Welcome to iBoats

:welcome:

The catalyst (hardener) should be about 6 drops per ounce of gelcoat. So, 1/2 cup (4 ounces) should get about 24 drops of hardener. My guess is that it is not going to harden with just "several drops" of hardener. . . more likely that issue vs. the age of the gelcoat. Any instructions on the can of gelcoat?

Acetone will wipe it right up, so you can take another run at it. Be careful not to use too much (acetone) nor apply it to surrounding areas.

 

[jbcurt00]

Gelcoat is based on polyester resin, and both the resin and the MEKP hardener loose effectiveness over time, esp the MEKP.

Might be the age or not enough MEKP. Metric is so much easier to measure w.

100ml resin gets 1-2ml MEKP, which is 1% to 2%. Try using 2% and see if you can get it to harden...

 

[Hibbertdl]

Thank yo both. Unfortunately, the instructions on the can say " Use the full tube of hardener for the full can of gelcoat; use half the tube for half a can, etc". So that wasn't very helpful for the small amount I was using. Unfortunately, the boat supply in my area lost it's lease since I bought that can of gelcoat. Guess I'll have to order another online (through iBoats, of course!). But that means another week without the boat. ☹

 

[ondarvr]

After a few years the likelihood of them working correctly is slim, but depending on temperature you would have needed 75-100 drops for 1/2 a cup. I'm not a drop guy, but sometimes that's all you have to work with. Measuring with CC's is easier.