Hi there

I'm relatively new to using composites and not familiar with the different types of resins available. I am looking to make fiber glass petrol tanks for competition motorcycles. There are a lot of people already using these on the Pre65 Trials circuit but in the last few years a lot of them have started to delaminate and bubble. Additionally the resin has been clogging up the carburettors. This is attributed to the Ethanol in modern fuels.

Is there a resin available that is resistant to ethanol even at the quantities used in E85 which has yet to reach our shores.

Many thanks

Steve

Hi there I to have just finished making carbon tank with Kevlar before I bond the parts together I will seal the tank,like you I've been looking for the right resin system but ethanol eats epoxy over time check out novalac tank sealer it says ethanol resistence,but it's very thixotropix so so don't think you can laminate with it,I already built my tank pieces,because I have peel ply finish should be able to brush on.be interested how you get on I can't 

here is what i found

ethanol friendly tank lining materials

CarbonFiberCreations

more info on this isssue but in boats. it goes into technical details of what is chemically happening

fuel tanks

CarbonFiberCreations

We don't stock any resins designed for petrol tank and ethanol resistance. You would likely need to use a special tank sealer after making the tank to ensure it is properly sealed.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Im no expert by any means but it sounds to me like the expoxy must be sealed away from the fuel. Maybe an automotive paint such as 2K would work as this dries rock hard, and as we all know when you spill petrol at the forecourt it doesn't peel away or react.

There is a big difference between occasionally pouring fuel over paint and soaking in it 24/7.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

I suppose yes, good point Warren. 

Many thanks for the advice. I was really hoping to laminate with it but I might have to settle for a coating. There have ben similar issues with some of these tank sealers but there is one on the market that everybody seems to swear by. I'll have to research it further and get back to you. If you haven't glued the 2 halves of your tank together yet, have you thought about having a flexible bladder made for it out of Viton or similar. This is what I was going to do but for the number of tanks I want to make of one shape this would be cost restricitve. However, if you've gone to the trouble of making a carbon fibre tank you might be happy with the cost. I can supply details of a good manufacturer if you want it.

Hi Warren - thanks for your reply. About a year ago I read about a Phenolic resin that was allegedly Ethanol proof. I think it was called Christic 99 but I can't find any record of it now. It's possible I imagined it and it could have just as easily been a vinylester or polyester resin, but from what I remember of the curing process it was most likely Phenolic. If I didn't imagine it, I'm not sure whether whether there is a gel coat that works with Phenolic resins. Possbily a polyester coating would but with reduced fire retardation, which I'd be prepared to live with if it was ethanol proof. Would you have access to any resources to be able to research this further please?