questions about polyester resin

[phatmanmike]

#1. can it be thinned with acetone or any other product?<br /><br />#2. can it be thickened with anything, such as wood flour or milled fibers or anything?<br /><br />#. can polyester reisn be applied over top of epoxy? i heard one will stick to the other but not the other way around, and cant remember what it was?

 

[BillP]

Re: questions about polyester resin

Originally posted by phatmanmike:<br /> #1. can it be thinned with acetone or any other product?<br /><br />#2. can it be thickened with anything, such as wood flour or milled fibers or anything?<br /><br />#. can polyester reisn be applied over top of epoxy? i heard one will stick to the other but not the other way around, and cant remember what it was?

1. Styrene is the correct thinner for polyester but acetone works.<br /><br />2. Yes, but thickening weakens it. Glass fibers are the best for strength. Milled fibers (cotton/linen)are the easiest to mix and use. Microballons for lightness and cabosil as a general "do it all" thickener. Flower comes in last but works too.<br /><br />3. Epoxy over polyester...not polyester over epoxy.

 

[Chris1956]

Re: questions about polyester resin

Mike, BillP has provided good advice. However, you can apply polyester resin over epoxy, if you sand and clean the cured epoxy to give it some "tooth".

 

[quantumleap]

Re: questions about polyester resin

BillP is correct, no polyester over epoxy. Sanding may make it adhere temporarily, but it will eventually de-laminate.

 

[Terry H]

Re: questions about polyester resin

agree with the delam business...been there, done that...just a thought

 

[CTD]

Re: questions about polyester resin

what about polyester gel coat over epoxy repairs?

 

[petrolhead]

Re: questions about polyester resin

Polyester gel coat is really no different to polyester resin, just thicker, it won't stick to epoxy for long no matter how well it's cleaned and keyed. Use epoxy over epoxy.

 

[thehermit]

Re: questions about polyester resin

The west system site does detail a procedure to apply geloat over an expoxy repair. Having had poly resin pull up in sheets before I dont think I would give it a try over epoxy.

 

[PW2]

Re: questions about polyester resin

There is no "thinner" for polyester resin. Styrene (monomer) is a cross linking agent, and is mixed in the proper proportions from the factory. Acetone will indeed make it thinner, but also less strong.

 

[Bondo]

Re: questions about polyester resin

#3) Polyester is a "Casting Resin".........<br /> Epoxy is a "Glue"...........

 

[quantumleap]

Re: questions about polyester resin

Bingo Bondo!

 

[petrolhead]

Re: questions about polyester resin

"Polyester is a "Casting Resin".........<br />Epoxy is a "Glue"..........."<br /><br />But interestingly epoxy makes an excellent casting resin too! I use it a lot at work where I need to cast something with a lot of fine detail, and/or where I need it to be tougher than a polyester casting.

 

[Hooty]

Re: questions about polyester resin

The best filler to use with polyester or epoxy is talc.<br /><br />c/6<br />Hooty

 

[BillP]

Re: questions about polyester resin

Originally posted by PW2:<br /> There is no "thinner" for polyester resin. Styrene (monomer) is a cross linking agent, and is mixed in the proper proportions from the factory. Acetone will indeed make it thinner, but also less strong.

Every resin mfg I've dealt with says styrene is "the" thinner to use with polyester...it is more compatible than acetone for the reasons you noted. Styrene is also superior for prepping surfaces to be glassed with polyester.<br /><br />Here's one supplier web that states styrene as a "preferred" thinner. This is universal.<br /><br /> http://www.fibreglast.com/showproducts-category-category-9.html#220