By "surfboard resin" I guess you mean polyester, a clear resin that you add about 1 percent catalyst to.

Polyester is sensitive to all sorts of other stuff especially water, even if it's a bit damp, it will slow setting quite a bit. It doesn't need air to go off, so tape shouldn't be a problem, but sometimes I've noticed some tape glues can also slow setting but that's only right next to the tape.
Heating will help it go off if it's going to, try putting under black plastic in the sun.

A "hot brew" on top of the old resin can also help, use up to 5 percent catalyst, but get it on quick, and don't leave the left over resin anywhere near flammable stuff!

Haven't seen your old post so not sure exactly what you're doing, but for most of the purposes you use carbon for, polyester isn't the ideal resin, it's too brittle to get the maximum strength from the carbon.

If you forgot to add the catalyst, then I think you'd better start again.

Thanks guys, I think the tape did slow down the curing process. I took some of the tape off left it in the sun room and it appears to have set.

keef said...

keef said...

if your looking to sand the carbon laminate, you will need to use a filler resin because some laminateing resins have wax and will clog your paper,

when i mentioned painters tape i thought you was useing epoxy ,polyester needs oxigen to cure
sorry about putting you on the wrong track des but waxed polyester resin helps the sanding what ever you do you will need a gloss coat heres a couple of fin's ive laminated and i'm sure it's the finnish your looking for

I think your wrong Keef, air hinders polyester setting not help it, that's why resin without wax (laminating/gellcoat), doesn't sand well, there's a thin layer of uncured resin on the surface that clogs the sandpaper. that's why filler resin has wax in it, the wax comes to the surface and excludes the air, allowing the surface resin to set.
It's also why another layer of resin on top of laminating resin forms a chemical bond, unlike filler resin, which has to be sanded before the next layer sticks, it's not a chemical bond it's mechanical.

BTW, nice looking fins!!!

But if you have spin out problems, they may work better if you give them a wet and dry with 400 grit

No I missed it, think that's when we were in Europe.