Gel Coat

1) Yes. Because it's not in a mass like the left over stuff it's not generating enough heat to set itself. It will go, may take 24 hours and leave a horrid waxy residue on top that eats wet & dry paper. It may still feel tacky after 24 hours. Appy washing up liquid and sand with 400 or 600 wet and dry. The tackyness is the wax residue.

2) Not really

3) Definatley.

Another thing which you should consider is that i assume that you haven't used any wax additive in your gelcoat which means that the gel will go off and feel but slightly tacky. The gelcoat normally reacts with the wax based binding agent in chopped strand matting and sorts this problem out, but when you do a repair there is obviously none of that.

How tacky are we talking, can you poke it about still or is it just slightly sticky if you run your hand across it?

I would suggest rubbing the top layer with acetone or something similar as it just removes the residue and then you can crack on wet and drying it without clogging up your paper straight away. Once you have wet and dried to 1200 you can then polish it with rubbing compound and robert is your mothers brother as they say.

If i give you any more tips our repair man will be out of a job as anyone could do it so i will bite my tongue for his sake!

Don't know about the stuff you can get these days, but back 'when i were a lad' I always used to cover over the repaired area with a taped-down piece of mylar film. This would (1) allow the shape to be set, hence less sanding (works well on a less gunwhale) and (2) meant there was no sticky surface after curing.

Don't know if this still applies to the gelcoat repair stuff around now.

As a short follow-up, I'm not sure where to cheaply/easily get mylar film in small amounts. These days I just snip pieces off a plastic (magazine freebie type) CD envelope....

Originally posted by Paramedic Originally posted by GK.LaserII According to our clubs glass fibre expert, who is a glass fibre engineer The curing of Polyester Gelcoat is aerobicly inhibited, the suface won't set unless covered with film to keep the air out as ColH suggested,. This should only effect the surface unless the gelcoat is applied very thin (less than .5mm approx)  and then non of it sets unless covered. Thats interesting. We've only found this a problem with old gelcoat that we've had over about 6 months and is starting to lose it's styrene content. Mix in some styrene and it's usually ok again, but that's a tip worth remembering.

I think the gelcoat in most peoples toolboxs will be over 6 months old (mine is). There is a "surface wax" additive for eliminating  surface tackiness.The tackiness is useful if applying multiple layers as it helps the layers to bond. The top coat needs to be covered to keep the air out.