Gel Coat Application

[MotoMike]

Hello, I'm a new member and wanted to ask for some advice. Making fiberglass moulds with tooling gel coat and isophthalic tooling resin. Plug is 14-inch by 16-inch. I have been applying 2 coats of gel coat of about 125 grams per coat using a cup gun. Shop temperature is 72 to 75 F. I have let gel coat dry for up to 48 hours before laminating but the moulds always seem to have a thin gel coat when held to the light. It seems like the resin pulls the pigment or dilutes the gel coat. Anyone have any ideas or am I just not applying enough gel coat?

Thanks.

Mike

 

[berkshire]

Go back to your resin supplier and get yourself a gel coat thickness gauge, a small metal or plastic step gauge.
After you have sprayed 90% of your gel coat check to see your applied thickness,you should have at least 18 to 20 mils.Put the rest of the gel coat in the thin areas right away, do not wait for the coat to gel and apply more.
You can start your layup when the gel coat is hard enough to write on with a ball point pen. Insufficient tooling gel thickness can result in "Alligatoring" in the mold.
B.E.

 

[MotoMike]

B.E.,

Thank you for the advice. I will pick up a thickness gauge. I did a test and added another 50 grams per coating. Turns out I may have been putting it on a little thin. I was concerned about getting it too thick and generating too much heat but everything looks good.

Thank you!

Mike