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Old 02-12-2013, 09:52 PM
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painted jester painted jester is offline

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Originally Posted by speedydeedy View Post
You seem to know a lot about the different resins. How about explaining Isothalic resin,I think I spelled it right.I was always taught that this was the best for making new car parts because it remains more flexible.Set me straight if I am wrong or explain it better if I am right.I have made and repaired a lot of race and street car glass parts but I am better at doing than writing.

Isophthalic resin I think your talking about? Its just a different product then the usually used Vinyl Ester resin when repairing boats in the top end shops!

Its like comparing the old Bondo Brand from 50 yrs. ago To the new fillers of today!


I found this so I'll copy and past! I type too slow to explain what you need LOL I"m not a Chemist LOL

"There is a big difference between isophthalic polyesters and vinylesters, worth every penny of extra cost. In any polyester, ortho- or iso-, the monomer is styrene (45% to 48% by volume usually). The polyester molecule is dissolved in the styrene. A peroxide compound, usually methyl ethyl ketone peroxide (MEKP) is used to catalyze the resin, which cross-links with some of the styrene, but not all of it. What styrene is not used in the chemical reaction flashes off, giving that fiberglassy smell, leaving microscopic holes in the laminate. It is through these holes that water passes during osmotic blistering.

Vinylester resin also uses styrene as a monomer in about the same proportions. And it also uses peroxides like MEKP as a catalyst. What is different though is that practically all of the styrene is used in the chemical reaction. Most of the styrene catalyzes with the vinylester, and the remainder crosslinks with itself, which makes polystyrene molecules within the resin. This closes off the vast majority of the microscopic holes in the resin, and this is why vinylester is so impervious to osmotic blistering. This is why chemical storage tanks, such as underground gasoline tanks, are always made with vinylester resin.

I always specify vinylester resin for blister protection and repair if the client does not want to use epoxy resin. Epoxy, by the way, is 100% solid, and therefore is the best blister barrier material."

As told by 2 big resin manufacturer tech's
"that the Iso. resins have also excellent resistance to blister. Without getting into specific manufacturers - They sell this particular Iso. as a 'matched performance system' for use with their marine gelcoat for use in 'marine' and other similar industries. This particular iso. costs as much as my gelcoat, but the V/E is about 75% more expensive, it's a DCPD modified V/E specifically for skincoats. They describe the iso. resin that if used with their gelcoat it offers a 'superior blister resistance'."

Last edited by painted jester; 02-12-2013 at 10:08 PM.
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