GEL COAT OVER WEST SYSTEM EPOXY

[FELLOW-SHIP]

Enclosed is correspondence regarding Gel Coat over West Systems Epoxy. This question was posted on their web site last week by me.
Question Comments:

THERE HAS BEEN SOME CONFUSION REGARDING APPLYING GEL COAT OVER A REPAIR JOB DONE WITH WEST EPOXY. I RE BUILD A 23' SEACRAFT AND USED APPROX 12 GAL OF WEST EPOXY TO RE DO THE DECK, CAP, AND TRANSOM I HAVE HERE TWO STORIES ONE YOU CANT RE GEL COAT A BOAT THAT HAS BEEN DONE WITH EPOXY RESIN AND NOW I AM HEARING THAT YOU CAN. COULD PLEASE LET ME KNOW WHAT IS THE ANSWER TO THIS QUESTION
THANKS
KEN

7-15-03

Ken:

We have had excellent results applying polyester gelcoat over WEST SYSTEM® epoxy for above the waterline repairs. To be successful, the epoxy has to be cured completely and needs to be washed with water and sanded completely dull with 180-grit or coarser sandpaper. If you fail to remove amine blush (forms on the surface of epoxy while it cures) with water or if you apply the gelcoat before the epoxy has cured completely (several days at or above 20°C.) you may experience gelcoat curing problems. Using 205 fast hardener will minimize potential for problems as it cures in cooler temperatures and achieves a complete cure considerably faster than when using 206 hardener. We have also applied polyester gelcoat successfully over WEST SYSTEM epoxy repairs after an overnight cure by heating the epoxy repair for several hours with a radiant heater to force it through its cure.

Part of the reason for the confusion is that many gelcoat producers offer instructions that say "Do Not Use Over Epoxy". They say this to minimize their likelihood of hearing from frustrated customers. In some ways I don't blame them because if the epoxy is not cured or if you fail to remove amine blush the gelcoat will not cure. Our experience shows that gelcoat works fine over epoxy repairs if you cure the epoxy thoroughly, remove the amine blush with water and an abrasive pad and sand with 180-grit sandpaper.

Please feel free to call or e-mail with questions or comments.

Regards,

Tom Pawlak
Technical Service