carbon rear stays help needed

[zaskar rider]

Hi All,

Ive just picked up a Kinesis racelight frame and the coating on the carbon rear stays is flaking off due to a harsh salty winter.... i can peel it back to solid with my fingernail... but what should i re-coat with and how should i do it ?

any advice would be great...thanks

chris

[cycleruk]

I wouldn't have thought that "salt" would have any effect on the finish of carbon structure.

I would try and contact Kinesis and ask their advice.
Is this a newish frame?

[steady eddy]

This is almost certainly a cosmetic laquer sprayed on to make it look good. Carbon fibre is either pre impregnated with resin and laid up under pressure or wet laid using epoxy. It is widely used in boat building and will not be affected by a bit of road salt. Unlike the aluminium frame which will gradually dissolve, whilst generating electricity for you.

Get the smallest quantity of West System 2 pack epoxy or similar from a yacht chandler or from Axminster.It is expensive. Rub off the laquer gently with wet and dry 400 grit or finer and recoat with the resin. (Do not sand the carbon) Do this somewhere warm and dry. Epoxy doesnt work well in cold or damp conditions. Do not mix up a large quantity of the resin as it is exothermic and generates heat during curing. Keep the resin off your hands, particularly if you have sensitive skin as it can cause an allergic reaction. Dont wate time trying to clean up brushes afterwards,just bin them. Although Acetone will clean up if necessary as will WD 40 at a push!!

Before you recoat, check for impact or stress damage which might have caused the surface to deteriorate. If you are in any doubt seek advice from a professional frame repairer who deals in carbon.

If the original finish was cellulose or a water based laquer then it is not surprising that it is comming off especially if the surace wasnt properly cleaned first. Epoxy mouldings produce what is known as an Amine Blush on curing, which is a slightly slimey finish. If this isnt properly cleaned off then getting any finish to stick or more resin to bond can be a problem. Conventionally 2 pack polyurathane is the only finish that really sticks to epoxy based mouldings.

Alternatively buy a can of laquer from Halfords and just respay it.

[[XAP]Bob]

Dump the brushes - grab a cheap brush from a local diy shop first.

It's cheaper than cleaning fluids.

[zaskar rider]

Hi all

great advice... thank you so much

cycleruk...it isnt a newish frame,i dont know how old it is or how long the racelight frames have been made for but it looks nice so i wanted to get it back to its former glory.

thanks again
chris

[sleeping_menace]

The only time I've seen that happen on a Kinesis, it wasn't salt, but a harsh solvent someone had used to clean off the chain and rear cassette. In the process, they'd managed to get it all over the rear stays, and not only did it affect the outer cosmetic coating, scratching at it with your fingernail it gave the impression that it'd affected the resin of the frame itself. Check it carefully, and make sure the damage is only cosmetic.

[zaskar rider]

thanks sleeping menace i'll have a close look

what should i be looking for ?

[sleeping_menace]

Just make sure it still feels absolutely solid.. and there's not the slightest hint of 'sponginess' if you will. It was subtle on the one frame I saw it happen to, but it'd been definitely been affected by it.

[zaskar rider]

aahhh thanks sleeping menace i'll have a squidge the next time im at my garage.. fingers crossed

[sleeping_menace]

Good luck with it..

The best way to describe the effect it'd had on this one..was that it gave the impression of the resin not quite being cured.. just.. barely still flexible.. This was VERY slight mind you, but with the rear stays, it's not an area of the bike which you want compromised. As long as you don't feel anything funky when you drag a fingernail over it.. or moreso, try to leave an imprint with the end of your nail, then you should be fine.