I wanted to check if it is still ok to lay down a coupling coat on top of a gel coat that has fully cured? Due to some unforeseen circumstances outside my control I was interrupted at the weekend when laying up a mould using the uni-mould system. Unfortunately I was only able to put down the gel coat. This will therefore have had 48 hours+ (probably most likely 56)  of curing before I can put down the coupling coat.

The gelcoat had a catalyst at about 2%, and has been curing in temp range between about 20-27 degrees. It has hardened and as of this morning had no discernable 'tackiness'. I just want to check it is still viable to lay down the coupling coat and 150csm? I imagine there should still be a bond between the two, but would it be advisable to put a key in the gelcoat?

Additionally i won't be able to finish off with the 450csm and tooling resin until the weekend, but I see previous advice on this forum suggests that will be fine if I key the coupling coat.

Many thanks.

If you give the gelcoat a good key with 120 grit paper and thorough clean  you should be fine.  A wipe over to clean with acetone might even help make the surface a little tacky again. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

+x

 

Warren (Staff) - 2/12/2020 10:37:30 AM

If you give the gelcoat a good key with 120 grit paper and thorough clean  you should be fine.  A wipe over to clean with acetone might even help make the surface a little tacky again. 

This worked fine, thanks. I wasn't able to get back to it for a week, and the gelcoat still had a bit of 'grab' when I came to give it a key. It (mostly) all removed from the plug fine. 

Glad to hear the project went well for you.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant