Compatibility: Polyester Putty and Epoxy Resin

[Aquabelle]

For the fiberglass experts: I have a job where I would like to fill a gap using a polyester 'putty' (like an automotive body filler) and then lay some 'glass in epoxy resin against it. I want them to adhere.

Any problem doing this?

 

[Comodave]

You can use epoxy over poly but not poly over epoxy.

 

[Sailor of Fortune]

I would stick with polyester resin and glass over a polyester putty or use an epoxy based (thickened "putty") with epoxy and glass over. Why mix the products?

 

[Insequent]

You can use epoxy over poly but not poly over epoxy.

And bear in mind that most epoxies do not fare well as far as UV is concerned. Given you cannot put polyester gelcoat/flowcoat on top of the epoxy, you would have to paint it for a final finish if your job is an exterior one.

 

[RT Firefly]

Greetings,
Mr. A. Also keep in mind the cloth must be epoxy compatible. One can use "epoxy cloth" with both epoxy and polyester but one can't use "polyester cloth" with epoxy. ONLY with polyester. Automotive type cloth can ONLY be used with polyester.

 

[psneeld]

No problem.....but not necessarily the best of all worlds.,,,but I have done it plenty of times as the filler is easier to work with and less expensive.



West Systems guide online tells you how to mix these products such as poly gel over epoxy with the right primer with no issues.


http://www.epoxyworks.com/index.php/polyester-over-epoxy/



"Our test clearly demonstrates that polyester gelcoat will bond to a properly prepared WEST SYSTEM epoxy as well as to a cured polyester laminate. This test confirms that polyester gelcoats can be applied over cured WEST SYSTEM ™ epoxy on repairs below the waterline."

 

[Aquabelle]

Yes psneed has it right: cheaper and easier to work with poly putty. Appreciate the advice and links provided