Gel coat over vinyl ester while still tacky?

[Gene Neill]

I tried to get my whole question in the title. I think I know the answer, but I'm hoping for some confirmation. Since gelcoat is polyester, and vinyl ester resin is, um, vinyl ester ... it seems to me that it would be not only acceptable, but preferential, to apply gelcoat while the resin is still at least slightly tacky.

True? False?

Cinnamon toast is delicious??

 

[Charles Erwin]

Yes poly gel coat is OK over vinyl ester but you will need PVA (or a wax additive) over the gel coat. That is because both vinyl and poly are air inhibited - which means that they do not harden until air deprived.

PVA is essentially a brush/spray on saran wrap - which cures the surface by depriving the surface of exposure to air - but it is easily washed off.

PVA is better than a wax additive according to some of us.

Charles

 

[finding41]

I'm a wax additive guy. My boat was made with wax in the gel-coat so...
Air access = sticky. No air = cured properly.
I have used PVA in the past for making parts but now I use Mothers carnauba wax. It is more work when I am making a mold but it forces me to pay more attention to detail when I'm preparing it.
Note: If you are doing a patch remember to wipe the gel-coat around the patch well with acetone to remove the old wax. (Yes there is still wax after all these years.)