Bloom and other marks on carbon frame - a concern or nothing to worry about?

[DCLane]

On the Ridley Damocles I've picked up there's very little laquer left and the carbon has a lot of bloom/marks.

I'm wondering whether this is a concern or it's just been over-cleaned? A photo of the typical marks are here:

I've no plans for the frame at the moment other than get it working, although it may turn into a bespoke hillclimb bike for my 14yo.

 

[Racing roadkill]

It looks like mostly issues with the paint / laquer to me. It looks worse because your getting to the inner layers. Unless you start to see actual fraying of the Carbon weave, or splits, I wouldn’t worry too much.

 

[Levo-Lon]

As above, lacquer looks like its reacted to cleaners and sunlight.
You often see this on older cars ,patches of white looking areas.

I'd think the frame would look great if it was stripped and either left or re lacquered.

 

[Drago]

Probably the lacquer.

Probably.

 

[DCLane]

Thanks - most of the laquer has been taken off by whatever cleaner the previous owner used. The bike looked to have been used in the winter and cleaned using something abrasive.

If I can source the missing parts needed I'll probably get a re-paint done. Hopefully I can find the correct decals, not just Damocles ones.

 

[Yellow Saddle]

I'm not quite sure what I'm looking at but I assume you've loosened a clamp and moved it up, to expose the white stuff on a carbon post?

If that is the case, you're looking at galvanic corrosion. There is a potential (electric current/voltage) active between aluminium and carbon in close contact, in the presence of water.

The white is aluminium oxide. The aluminium component is the one that gets sacrificed. The only solution is to electrically isolate the two. Usually paint does the job but it often fails at a small point and then lifts the paint off from the inside, spreading all over the contact area.

The carbon will be structurally fine and probably so, the aluminium. You'll notice when it gets really rotten and holes start to appear.

 

[DCLane]

I'm not quite sure what I'm looking at but I assume you've loosened a clamp and moved it up, to expose the white stuff on a carbon post?

Sort of - some of it was where the clamp was, other bits away from the clamp. The bike's come as a load of mostly complete bits plus some broken parts left on - so the seat clamp wasn't attached at the time.

 

[Yellow Saddle]

Sort of - some of it was where the clamp was, other bits away from the clamp. The bike's come as a load of mostly complete bits plus some broken parts left on - so the seat clamp wasn't attached at the time.

Without a full photo I can't really see what's going on. It does look as if the white area's border matches the aluminium casting's outline. Either way, aluminium in contact with carbon is a bad idea. But just because it is a bad idea, it doesn't mean frame manufacturers don't do it. I've seen plenty of it. It does help if the aluminium is passified before connected. This can be done by anodising. However, anodising doesn't work on the inside of hollow structures which are effectively Farraday shields.

In the early day of carbon frames, the BB shell used to be an aluminium BSA threaded tube glued into the carbon frame. This is so problematic that frame companies moved over to pressfit BBs, which open a large Pandora's box of their own.

Nevertheless, you'll never see exposed carbon fibres/weavebecause the resin isn't involved in the reaction, only the carbon and aluminium.