Are there different catalyst's for gelcoat for different temperatures?

[sbklf]

It is in the 50's here in Houston. I heated my garage to about 65 and applied waxed gelcoat with a little extra catalyst to the hatches of my boat. After two days it is still tacky on top and I can take the gelcoat off with an acetone soaked rag. My resin supplier said the gelcoat did not cure properly probably due to the temp. He said that I should be able to run an acetone rag over the surface and remove wax only and no gelcoat after a day. I called a local shop who was careful not to reveal any trade secrets but implied that different techniqes and different products, one of which was different catalyst, could be used in the gelcoat to get it to cure in the cold temps as he does it all the time.

Is my supplier correct that the gelcoat probably did not cure and that it should not wipe off with acetone after a day?

Are there different catalysts for cold weather?

Can someone tell me any other tricks or clue me in on other additives I might consider using so I can finish now rather than wait till summer?

 

[ondarvr]

Re: Are there different catalyst's for gelcoat for different temperatures?

There are many different catalysts that can be used, the problem is you won't be able to get them in the retail market, the other thing is, you still need to have adequate temps for it to cure correctly. 65* should be fine though and when you said you added extra catalyst how much extra did you add? Never go more than 3% on gel coat.

Gel coat normally cures well on the back side when wax is added, but it's not formulated or designed to be used in this way, so no QC testing is done to ensure you will get a good backside cure. Some gel coats have additives that can inhibit the surface cure even with wax, backside cure can also be affected by the pigments added to make each color, so you may not always get the same results.

Since you're doing a fairly small area, try using a heat lamp, but be very carful, you need to keep it at least 3' feet away or you risk over heating the gel coat.

 

[sbklf]

Re: Are there different catalyst's for gelcoat for different temperatures?

There are many different catalysts that can be used, the problem is you won't be able to get them in the retail market, the other thing is, you still need to have adequate temps for it to cure correctly. 65* should be fine though and when you said you added extra catalyst how much extra did you add? Never go more than 3% on gel coat.

Gel coat normally cures well on the back side when wax is added, but it's not formulated or designed to be used in this way, so no QC testing is done to ensure you will get a good backside cure. Some gel coats have additives that can inhibit the surface cure even with wax, backside cure can also be affected by the pigments added to make each color, so you may not always get the same results.

Since you're doing a fairly small area, try using a heat lamp, but be very carful, you need to keep it at least 3' feet away or you risk over heating the gel caot.

I added one extra teaspoon to 24 oz of gelcoat I think. I went by the sheet that said 4 tsp per quart. That would be 33% more than recomended. I heard the wax rises to the top, topside is this not the case?

 

[ondarvr]

Re: Are there different catalyst's for gelcoat for different temperatures?

Without checking I can't remember what % 4 tsp's is to 32 oz's, but if it's in the 2-3% range your OK.

Yes the wax will rise to the surface, but even when it does, sometimes the surface may stay slightly tacky and depending on the type of gel coat it may cure very well, or not so well.

Make sure the wax solution is warm and mixed well before you use it. If the wax solution gets cold the wax will sart to solidify and separate from the styrene it's desolved in, if that happens you need to warm it back up and remix it.