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.