How bad is polyester resin?
 

Hey guys,
I'm about to purchase some carbon parts. However, the company uses polyester resin and not epoxy for their carbon production. I asked around and did some google searches and found that polyester is of the lower quality. Making me extremely hesitant to go with the purchase.

I know many of you have carbon parts so I want to ask. How much of a difference is it? Is polyester really that brittle and will just shatter at the sight of sunlight or even a light bend?

my car will be parked indoors, but of course it will see sunlight and i won't be painting the parts anytime soon.

I have the option for fiberglass parts. Should i just opt for that instead?

Eboxy?:seriously:

Your fine many boat are made with polyester resin.

It depends on the parts. For a sub-enclosure, polyester & fibreglass are the way to go. For a hood or fender, you'd want epoxy, vacuum bagged with a proper gel coat, finish, and careful strand/weave orientation. You have to see the pieces and make sure they are as nice as the pieces they advertise on the website.

Epoxy binds more effectively to strands than polyester does - so for a load bearing part like a hood, epoxy is a good idea.

Vinyl ester is an okay medium as well..

my bad lol epoxy*

The part i'm getting are front fenders. No load on it. I'm just really worried they will deform and turn into a ugly yellow color. I've been hearing some horror stories of polyester, but also some good ones.. not sure what to believe lol. But thanks.

Epoxy resins are better. They don't discolor with exposure to UV, they are more flexible, more water resistant so they don't "fog" over and are more suited for higher heat applications. Most importantly when making parts for visual esthetics most epoxy resins dry crystal clear. Most polyester resins dry with a slight yellow tint.