Gelcoat issues need advice.

[BarrySpc]

I have replaced the casting deck in my 17 foot flats skiff. I glassed the plywood to help waterproof the deck and everything has went as expected until the Gel coat. I'm using Hi-Bond Gel Coat with wax and its not curing, it's been over 24 hours and it's still very tacky. I bought a quart and measured out 16 oz. and added half the hardener (well to the 1/8th oz. mark on the bottle) and mixed for about a minute to minute and a half. Does anyone have any ideas on why the Gel coat isn't curing out and what can I do to get this to harden?

I still have a pint of Gel coat and an 1/8th oz. of hardener is it as easy as mixing up the rest and applying another coat? Or am I going to have to remove the Gel coat first? Thanks in advance.

 

[jbcurt00]

Re: Gelcoat issues need advice.

I suspect you under catalyzed the gelcoat by 50%.

1.5% of 16oz is 0.24oz, roughly 1/4oz.....

^^^ one of the reasons metric often works better: 100ml of resin uses 1.5mls of hardener.

Very tacky or just tacky?

What was the weather like when you applied the gel? Temp~Humidity? Did temps drop overnight?

It'd have to be well over 100* for .75% catalyzed gel to kick.

The gelcoat resin already had the wax mixed in? You mixed it well before pouring out 1/2 to use?

 

[BarrySpc]

Re: Gelcoat issues need advice.

This is kinda what I was thinking

But I mixed it as per the Directions They state to add 1/8th oz. (4cc) to 1 pint, add 1/4th oz. (8cc) to 1 quart or add 1 oz. (30cc) to 1 gallon. I will say there is a mark on the hardener bottle that says 1/8th oz and I add the hardener to that line so I don't know how accurate that line is.

It is more of a wet tacky

The weather was about 93 - 94 degrees with about 75 - 80% (Melbourne, FL)

The gel coat came with the wax mixed already, I shook the crap out of the can before I opened it for about 5 minutes. Than used a stir stick for about 30 seconds, than poured 1/2 out.

Never the less if it is under catalyzed how do i fix it.

 

[glenn property of pam]

Re: Gelcoat issues need advice.

I would take a tee spoon of gel coat and mix in 2 drops of hardener and apply to a scrap of sealed wood or plastic and see if it kicks just to be sure that the gel they sold you had wax in it. It should kick real quick. Some gel coat does not have the wax mixed in at production but is added by the place that sold it at a later date then remarked as having added wax.

 

[BarrySpc]

Re: Gelcoat issues need advice.

There are some spots around the edges that have hardened and it does feel like it has wax. What next? Can I just mix up the rest and applying another coat?

 

[Woodonglass]

Re: Gelcoat issues need advice.

Nope. Waxed gelcoat will need to be sanded well and wiped down well with acetone prior to another coat of gel being applied. You normally used unwaxed gelcoat for larger gelcoating areas, apply 3-4 coats of gelcoat, and apply the wax to the final coat. The wax can make the bonding of the second coat problematic.

 

[BarrySpc]

Re: Gelcoat issues need advice.

So how do I remove this gel coat when its for the most part still wet? I cant sand it and I don't think it will ever harden.

 

[glenn property of pam]

Re: Gelcoat issues need advice.

still wet needs to be explained. gel coat can be dry but sticky or it can be wet and acting like unset paint that comes off on your fingers when you touch it. If its hard but sticky then use mold release spray to take the sticky off the surface so it can be sanded. If its wet and comes off on your fingers then test the product you have to see if its a bad batch and either add another coat in the hope it will set the first coat (test area) at least then it can be sanded back off or scrape and acetone.

 

[ondarvr]

Re: Gelcoat issues need advice.

4cc per pint is a very low level, but since this product isn't one sold in this part of the world and we have no expereince with it, it could be formulated for the amount.

Did you do this outside in direct sunlight? This can cause the surface to stay tacky.

If it's still tacky after a day or so there isn't much hope for it to become tack free no matter what you do, it will dry out, but it will still be soft and dirt will stick to it.

In a normal situation I would say to remove it before applying another layer, but if it's still tacky the next layer will bond rather well, plus this is above the waterline and rolled onto a floor.

If you had enough working time at that catalyst level I would add more the next time just to make sure.

 

[Woodonglass]

Re: Gelcoat issues need advice.

I'd prolly try a very stiff putty knife to scrape it off.

 

[BarrySpc]

Re: Gelcoat issues need advice.

I want to say Thanks for all the replies.

Just an update though...
I went ahead and got some Evercoat PVA Mold Release and sprayed it on and after an hour and a half it seem to be working. I still have 2 1/2 to 4 1/2 more hours before fully cured. I will be sanding and reapplying the gel coat tomorrow, now my only question is how much hardener to use?