Fibreglass resins

John Lowe · 05-07-07, 06:32 AM

Help for Newbie. I am in the short strokes of deciding which GT40 replica to go for (RCR v CAV). Can any of you guys tell me why Vinylester resin claims to be superior to Polyester resin when used in a car body? Is the difference big enough to make any real difference in practice?

Love the build site's especially Bill's, you can almost feel the heart he is putting into his 40.

Thanks in eager anticipation

John

Growin' old Disgracefully!

FRPGUY · 05-07-07, 07:41 AM

John, I use both resins in the GT40 bodies I make. The vinylester's end product is a stronger, more ridged, and most important; more stable in high heat. It doesn't go soft in the sun light. It doesn't burn as fast as polyester also. The down side of vinylester resin is that it is more difficult to use in the wet layup process and it costs more money in it's promoted state. Four years ago I was paying $400.00 USD per 55 gallon drum, now it's $1800.00 USD per drum. It was the same resin that Factory Five uses. Polyester is $750.00 USD per drum. I'm making everything with polyester now! I buy the best polyester that's avialable now.

John Lowe · 05-07-07, 07:51 AM

Don't know how to address you FPRGuy. Anyhow thanks for quick and informed response, most helpfull. First technical question on the site and the guy who answers has a birthday one day away from mine, we scorpio's got to stick together!

Regards

John

John Lowe · 05-07-07, 07:53 AM

OOps should be FRPGuy. Hunt and peck typing not up to much!

Mark Worthington · 05-07-07, 11:27 AM

John, you can call him Bill.

The other thing to consider is that, as a practical matter, it is very difficult to find vinyl ester resin. I'd like to have some on hand for the samll amount of wet layup work that I need to do, but I have been unable to find it.

John Lowe · 05-07-07, 01:25 PM

Mark

Thanks for the info. The only "specialist" site's I can find are to do with boat hulls.

Regards - John

FRPGUY · 05-07-07, 01:56 PM

Mark, I buy my resins from Composites One in Bristol, RI 1-401-253-4800
The vinyl resin I use only comes in 55 galon drums, but they do have some other types of vinyl resin in 5 gallon pails. The problem with vinylester resin; is that it has to be permoted ( the addition of some active chemicals so it will cure when you add the hardener ) either by you or by the company that sells it. It has a short shelf life with these chemicals added. Vinyle works best with a post heat cure also.
John, a good quality polyester makes for a good GT40 body jsut like the originals.

John Lowe · 05-07-07, 02:54 PM

Bill

Thanks. Opinion of a pro is reassuring.

John

chuck smith · 05-07-07, 04:24 PM

can you use polyester resin to repair a vinylester body with damage? I have that issue coming up on my CAV.

BruceLambo · 05-07-07, 05:37 PM

I have been using Epoxy resin with all my carbon stuff over the last few years. Definate strength improvement. I know its damn expensive, but I have contacts in the boat building industry who get it for me at a fraction of the shop price, so its all I use now. One good reason Ive been using it is that it doesnt melt styrofoam or similar. So you can acurately form parts out of foam and glass straight over them without the foam melting.

FRPGUY · 05-08-07, 07:43 AM

Chuck, You can use polyester to fix vinylester, just rough up the surface areas really well.
Bruce, I do the same with the epoxy and foam sometimes. I usually use a foam to shape out parts that doesn't melt with polyester. It's made for the composite industry.... and not cheap! I use vinylester with carbon with great results.