Carbon fibre epoxy resin & sunshine

[Rothgo Wooft]

Can anyone recommend a suitable epoxy resin for doing some decorative carbon bits and pieces?

A crystal clear resin, with high UV resistance. Its going to be in the sun all day everyday (in Spain, not here!). Should it be lacquered, or just polish up the resin?

Does anyone have any old CF that's seen a lot of sunlight? How did it hold up?

cheers for any information.

[Sam_68]

Rothgo Wooft said:

Does anyone have any old CF that's seen a lot of sunlight? How did it hold up?

I have a whole car made out of the stuff, manufactured in 1999, but I couldn't say how much time it has spent exposed to strong sunlight.

The main chassis tub (epoxy resin) is basically as new, with no fading at all.

The bodywork (moulded in polyester resin)was laquered, but has gone a bit milky despite the laquer. I'm planning to get the bodywork resprayed this year, as a result.

My understanding (backed up by experience on my car) is that epoxy is relatively UV stable compared to polyester, though a coat of laquer on top of it wouldn't do any harm.

[Rothgo Wooft]

No fading in 11 years sounds good to me. I read in a few places the epoxy resins are naturally UV resistant, but was a little sceptical.

Anyone sunbathed their CF for longer?

[gtmdriver]

In their literature West, who make a common epoxy system say that .........

"Paint or varnish applied over an epoxy barrier coat is intended to decorate the surface and protect the epoxy from sunlight. In so doing, the finish coating extends the life of the epoxy moisture barrier which, in turn, provides a stable base that extends the life of the finish coating. Together, the two form a protective system far more durable than either coating by itself."

I don't know if this applies to other epoxy coatings but I would imagine so.

[ezakimak]

I was chatting to a few mates the other night – urban legend stories type stuff – apparently a couple of years back there was a guy (and his wife) that flew their home built aircraft to an air show. It was an unpainted (might have been lacquered in clear) so to speak and basically carbon black weave in all its glory. The plane sat outside all day in the sun at the show. Apparently the wings/plane folded up just after takeoff as the resin had re-activated and lost all its structural strength. Both husband and wife perished.

Haven’t been able to confirm it as fact – but it’s made me wary of the subject.

[singlecoil]

ezakimak said:

I was chatting to a few mates the other night – urban legend stories type stuff – apparently a couple of years back there was a guy (and his wife) that flew their home built aircraft to an air show. It was an unpainted (might have been lacquered in clear) so to speak and basically carbon black weave in all its glory. The plane sat outside all day in the sun at the show. Apparently the wings/plane folded up just after takeoff as the resin had re-activated and lost all its structural strength. Both husband and wife perished.

Haven’t been able to confirm it as fact – but it’s made me wary of the subject.

It seems very unlikely to me, most epoxy resins cure with heat, the sort used in aircraft actually require heat in order to cure properly. In my younger days I worked at a specialist composite materials places and they had large walk-in ovens for this purpose

[gtmdriver]

I don't think epoxies have a structural problem and I doubt that it's heat related.

It's a slow degradation of the surface layer due to prolonged exposure to UV light.

[Z4MFarmerpalmer]

I do a lot of gliding and as such pretty much all the modern gliders are Carbon/epoxy, most parts are post cured after the initial cure and are all painted white to protect from extreme temps that would occur with just carbon weave in direct sunlight, I know there have been studies done in the States re the the temps a plain black carbon wing would reach in direct sunlight and there was a critical temp when failure would be likely (can`t remember the figue of the top of my head mind!).
Unless pre pregs are used I would imagine that a polyester gel coat (clear) would have been used as epoxy tends not to sit well on wax release agents and this could cause discolouration over time in direct sunlight. I dare say you could sand off the gel and then build it up using 2k lacker?

[Mabbx]

I work for an epoxy/PU manufacturer. We supply our resins to these guys who make their own parts and supply kits for the home user in carbon fibre - www.carbonmods.co.uk. Epoxy's are not UV stable but do have a degree of UV resistance. Due to the thin coating of epoxy resin required to wet-out the carbon cloth, the discolouration is very difficult to see and will take many years to yellow.

Hope this helps.

[Rothgo Wooft]

CarbonMods seems to know their stuff, but I may be looking at some fairly large quantities. It would be useful to know the specific epoxy, hardener, lacquer & additives combination to compare prices. I expect they don't write it on the labels though! There seems to be a fair bit of secrecy about such things, and interweb trawling is coming up with lots of differing opinions on manufacturers. Coming to some conclusions, but nothing solid. Getting a bit from each and comparing isn't really practical as I'd have to wait several years to see the results.

If anyone cares to PM on the subject, rather than write it on a public forum, I promise to keep the secrets safe. The use I have in mind is not related to cars or supplying kits of anything, and so won't be in competition with anyone. However, it would still be sensible for me to keep the information to myself.

Any gurus out there?

[dazm]

Silmar 459 - it's not an epoxy but a polyester resin used to make surfboards usually. Very good UV resistance especially when given a coat of laquer afterwards too. It's what most companies that 'wrap' parts in real carbon use - although most will insist they use an epoxy!

You could always call up a resin manufacturer and ask what they'd recommend too. Matrix composites in Bristol are generally pretty good for hobby quantities, although some of the big suppliers may sell smaller quanitities to individuals if you ask nicely...

[mikeveal]

Give CFS Cornish Fibreglass supplies a call (you find them easily iwht Google.) They should answer your question.

[robm3]

Mabbx said:

I work for an epoxy/PU manufacturer. We supply our resins to these guys who make their own parts and supply kits for the home user in carbon fibre - www.carbonmods.co.uk. Epoxy's are not UV stable but do have a degree of UV resistance. Due to the thin coating of epoxy resin required to wet-out the carbon cloth, the discolouration is very difficult to see and will take many years to yellow.

Hope this helps.

Mabbx, I have a carbon spoiler that's been lacquered but now has stone chips on it, can you suggest anything that can remove the lacquer (at least I think it's lacquer) without damaging the carbon fibre weave underneath?

[Rothgo Wooft]

robm3 said:

Mabbx said:

I work for an epoxy/PU manufacturer. We supply our resins to these guys who make their own parts and supply kits for the home user in carbon fibre - www.carbonmods.co.uk. Epoxy's are not UV stable but do have a degree of UV resistance. Due to the thin coating of epoxy resin required to wet-out the carbon cloth, the discolouration is very difficult to see and will take many years to yellow.

Hope this helps.

Mabbx, I have a carbon spoiler that's been lacquered but now has stone chips on it, can you suggest anything that can remove the lacquer (at least I think it's lacquer) without damaging the carbon fibre weave underneath?

An interesting question, that I'd also like to know the answer to.

[Z4MFarmerpalmer]

Rothgo Wooft said:

robm3 said:

Mabbx said:

Mabbx, I have a carbon spoiler that's been lacquered but now has stone chips on it, can you suggest anything that can remove the lacquer (at least I think it's lacquer) without damaging the carbon fibre weave underneath?

An interesting question, that I'd also like to know the answer to.

The only method I know of is good old elbow grease, wet and dry used wet then respray with lacquer, flat and polish up to a good shine with G3 or the like.

[Mabbx]

robm3 said:

Mabbx said:

I work for an epoxy/PU manufacturer. We supply our resins to these guys who make their own parts and supply kits for the home user in carbon fibre - www.carbonmods.co.uk. Epoxy's are not UV stable but do have a degree of UV resistance. Due to the thin coating of epoxy resin required to wet-out the carbon cloth, the discolouration is very difficult to see and will take many years to yellow.

Hope this helps.

Mabbx, I have a carbon spoiler that's been lacquered but now has stone chips on it, can you suggest anything that can remove the lacquer (at least I think it's lacquer) without damaging the carbon fibre weave underneath?

Accetone will deteriorate poyester/polyerethane and epoxy but I would not suggest you use it as it will effect the carbon. If you are looking to make as good as new again you have a couple of options. One would be to wet and dry out the chips and get re-coated in a lacquer or you could try floating in some resin into the chips and flatting back out. Hope this helps. Another company I deal with - streamline Carbon put a UV lacquer on thier parts. They may be able to help with re-spraying