[Closed] Carbon care.

Might stop it from dulling in the sun

Interetsing stuff, I found this article:[url= http://me.eng.sunysb.edu/~compmech/downloads/N29.pdf ]Article[/url]

From what I can gather quickly skimming it is that damage can occur when both intense UV, and 100% humidity at 50c is used for extended periods of time:

[i]"For this case, specimens were exposed to UV
radiation in the 295–365 nm band at a temperature of 60C
An irradiance level of 0.68W/m2 at 340 nm was chosen to match the typical maximum irradiance of summer sunlight at noon.

In this exposure condition, the specimens were exposed
to water vapor condensation at 50C. Condensation on the specimen surface was achieved by water evaporation and resulted in 100% relative humidity inside the testing
chamber.

It was observed that only
1000 h of cyclic exposure to both UV radiation and condensation resulted in a 29%
decrease in the transverse tensile strength of the material."[/i]

I think its important to remember though, that most carbon kit has a cosmetic carbon veneer outer layer whch will protect the structural carbon from uv, and a layer of laquer, which will protect it from condensation, so it's probably a non issue, or a cosmetic one at best.

From LB website:

Our rims are constructed with a 3k weave on the nipple bed regardless of what the outer (aesthetic) ply is, so it is okay to use UD on the outer ply of the rim. It does not significantly impact the weight or strength of the rim.

Buy a pack of baby wipes and save yourself a fortune.

Moisture absorption and high temperature certainly has an effect on carbon's strength, laquer layer or not there will be moisture ingress and the material properties will be degraded.

Hopefully your carbon bits will be designed with this in mind. If anything could prevent it then why not use it, however I would doubt somewhat that anything would be particularly effective.

I would hope that the makeup of the filler would include something to provide protection against the UV, and there should as above be a scrim layer which will absorb some anyway.

It's not the carbon itself that suffers from wetness/UV/heat, it's the matrix, particularly if you have a low cure temperature matrix it can't be expected to work well as the temperature approaches your cure temperature.

Edit- some grades of aluminium alloy will suffer permanent degradation of material properties at below 100°C too...

It's the epoxy matrix and any thermoplastic tougheners and resin to fibre coupling agents that break down over time with moisture (hydrolysis) and UV exposure. Normally you have a clear coat lacquer or paint that is UV resistant.

In reality how long does your bike actually stay in the direct sun or submerged in water or in a very humid environment?

I would expect the plastic parts n your grips, saddle, shifters etc to start showing signs ofuv damage before the carbon fibre.

'Emperors new clothes' product innit, sunscreen for carbon bicycles?

There's a fair few carbon road frames knocking about well over a decade old now none seem to be crumbling in sunlight...

I clean carbon fibre bike frames/wheels with isopropyl alcohol, then treat the appropriate surfaces with a bike specific polish that's carbon friendly.

If a bike is particularly dirty we'd use our rozone parts washer and then diluted Muc-Off before a wipe with the isopropyl and polishing.

Fibre grip carbon paste(seat post), finish line Teflon grease (press fit BB and headset bearings)and anti seize where appropriate

"For this case, specimens were exposed to UV
radiation in the 295–365 nm band at a temperature of 60C
An irradiance level of 0.68W/m2 at 340 nm was chosen to match the typical maximum irradiance of summer sunlight at noon.

In this exposure condition, the specimens were exposed
to water vapor condensation at 50C. Condensation on the specimen surface was achieved by water evaporation and resulted in 100% relative humidity inside the testing
chamber.

It was observed that only
1000 h of cyclic exposure to both UV radiation and condensation resulted in a 29%
decrease in the transverse tensile strength of the material."

That sounds like they put it in a QUV cabinet. 1000h is a fairly long duration given that the cabinet is designed to accelerate natural weathering processes.

Andyl is pretty spot on. The kind of testing they are looking at is what we use for paints and coatings exposed to the weather year round. Your bike will be fine. IT won't be UV degredation that breaks it.

I clean carbon fibre bike frames/wheels with isopropyl alcoho

I wouldn't recommend solvents on a carbon fibre components - probably worse than UV. Soap, water and polish if you are really bothered.