Idiots guide to repairing gelcoat......

RutlandMike

RutlandMike

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2 Sep 2006
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Had a small catastrophe yesterday and took a chunk of gelcoat off my port stern ...don't ask...! Not having repaired gelcoat before, I'd be very grateful for an idiots guide or pointers as to where one exists. Thanks in anticipation.
 
Cheers Brendan, much appreciated. I did try to search but came up with tons of stuff which didn't seem to have a lot to do with repairing gelcoat.
 
I had alook at that thread and am now very confused. It may be a question of wording. (me being a foreigner)
As I was taught catalyst is put in to "promote "the resin and this is usually done before the resin is sold. I have done a lot of fibreglass work over the years and never added catalyst to polyester resin.

When the hardener is added the resin goes hard because it reacts with the calalyst. Hardener is an oxidiser usually Methyll ethyl Ketone peroxide. MEKP which is added in small proportions.

The actual amount of hardener added depends on temp of the day the amount you are mixing and the speed you expect to use it. A large pot will exotherm ie get hot and go hard quite quickly compared to the speed it hardens when spread out on the job.If you don't add enough headener it will take longer to harden but this can be fixed by providing heat to the job.

If you are doing a small gel coat repair using perhaps a teaspoon of resin then you can add 3 or 4 drops of hardener ( a high proportion) becaue you will have it on the boat in seconds and want it to harden quickly.
By the way I had a friend ask me why his gel coat filler wouldn't harden. It turned out he had bought a little bottle of pigment and in fact there was no resin in what he was applying just colour. The pigment goes into resin then add hardener to get it hard.

Now I didn't write this thread to argue about wording. I may be wrong but I suspect that from popular miss usage catalyst has been confused with hardener. I simply want to warn that you should make sure the wording you use gets what you want. ie make sure poyester resin is already promoted with catalyst and that you buy the correct hardener.
From there the best trick is to try a test piece first. good luck olewill
 
I think that its just a language problem. In our yard it's nearly allways called catalyst or butanox. Igf only to not to confouse it with hardner that goes in epoxy. /forums/images/graemlins/smile.gif
 
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