I having given it two gel coats first coat catalized at 2% and second gelcoat at 1% because I wasn't sure of open time for coupling coat,I think am going to bring part to work and give it coupling coat mid morning then apply main reienforcement about 6 that should be sufficient time.

I have used 2% Catalyst in the past on the gel coat because at 1% the gel coat was taking too long to go off and eating/attacking  the plastic part I was moulding off. 

Carbon Copies Ltd

I usually make my molds from epoxy so the open time is crucial,this is first time using unimo

Hi, assuming you are talking about the Uni-Mould System. I usually apply the coupling coat when the gel coat is tacky 5/6 hours. But recently I left it for two days (not intentionally). I have also quickened the process by using heat ( 6/7 hours for the whole mould). I am not suggesting that either would be recommend by EC but both moulds have been used for Infusion multiple times and are holding up well.

Does any one no the maximum open time is before coupling coat can be applied can the open time be days.