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Weird air bubbles under top coat of carbon frame

24K views 52 replies 20 participants last post by  rkb 
#1 · (Edited)
For the last couple of weeks, I've been ripping around on a new carbon roadie. It's been fantastic and has rejuvinated my love for riding again! I needed that!

Unfortunately, over the last couple of weeks or so, I've noticed some weird air bubbles under the clear coat on the top tube of my carbon roadie. The bubbles are sandwiched between the clear coat and the carbon weave underneath. You can't feel them with your fingers. There's no sign of damage, etc anywhere near the sections. None of the other tubes seems to have this issue…just the top tube. Weird. These certainly were NOT there when I bought the bike new.

Here's a pic:



Unfortunately, since I noticed it a week ago, it looks like it is spreading. There are 3 distinct areas along the top tube where there are air bubbles. I'm sure it's cosmetic at this point, but, part of the strength in carbon comes from the outer layer. If that's starting to have issues, it could mean probs down the road. And, since it's spreading, I'm concerned!

What do you think?
 
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#2 ·
wow, that is wierd...I never heard of anything like that....could it be the fiber de-laminating?


can you see the bubbles?.....I can't tell from the pic, all I can see is a bulge....if it is indeed spreading I would be more than a little concerned. Talk to the mfr.
 
#4 ·
Touch0Gray said:
wow, that is wierd...I never heard of anything like that....could it be the fiber de-laminating?
I certainly hope not! But, I've sent an email with the picture to the manufacturer, the distributor and the LBS to see what they think. I don't think it's good as it should NOT be doing that. IMHO, in order for the air bubbles to form, the tube must be flexing/twisting. I'm only 135lbs, so I don't think I do that much to a frame ;)

Gotta say, this is my first carbon roadie (after years of Ti) and I'm glad I'm buying a Moots Ti roadie on Monday! :thumbsup:

can you see the bubbles?
Yes. The pic shows the non-drive-side view of the top tube near the head tube. Just back from the head tube bulge (top left corner of pic), there's a series of air bubbles on the top of the top tube that extends down the non-drive-side side of the top tube. The bubbles are pretty much right in the middle of the pic.
 
#6 ·
My frame something similar on both sides of the down tube, near the head tube. It was there when I bought the frame (I got a discount because of them). I haven't noticed them getting any worse, however.

The rep for this area, the LBS owner and I all discussed it and decided it wasn't a problem other than looks.

Of course, I got assured that IF it became and issue down the road, it would be covered under warranty.
 
#8 · (Edited)
looks like a bonding issue (resin to CF). Should be covered under warranty.

Maybe someone had KFC for lunch and touched that spot with their greasy fingers prior to impregnating with resin/curing under vacuum.

could also just be that the vacuum pressure wasn't high enough in that spot during curing
 
#10 ·
in theory, the bonding of resin to CF is very important for the overall performance of the composite system. While that may not be a critical location of stress (top tube near seat post doesn't seem too critical), it is more than cosmetic. If nothing else it affects resale value should you try to sell it.

as far as what it actually is, I am just speculating of course.
 
#11 ·
Yes, I understand the theory of composites and would think that if there's a degradation of the composite (in any way), it weakens the overall structure. That's why I'm concerned...and, by the fact that it is spreading. When I first noticed it a couple weeks ago, it was just a few dots on the top of the top tube. Over the course of 10 days or so with some mileage, the dots seem to be propagating down the non-drive-side of the top tube. Also, a second spot has appeared further down the top tube towards the seat tube. FWIW, the area in the pic is a couple inches behind the head tube, not seat tube.
 
#12 ·
Brought my bike down to the LBS so they could have a personal visual inspection. They were confused as to how/what/why the bubbles are there? They've taken more digital pictures and spoken with both the local distributor and the manufacturer. We'll see what they say....
 
#13 ·
I would be concerned but I'd certainly not jump to conclusions and assume it was something wrong with the carbon fiber layup. While it could be that, it could just as likely (more likely?) be a problem with the clear coat. Let the LBS work with the factory rep and determine the proper course of action. I see a new frame in your future, whether it's a clear coat problem or something more serious.
 
#14 ·
Mel Erickson said:
I would be concerned but I'd certainly not jump to conclusions and assume it was something wrong with the carbon fiber layup.
Agreed....I'm certainly not a carbon expert, although I do have some opinions on the subject. But, I'll let the experts decide what happened.

Let the LBS work with the factory rep and determine the proper course of action. I see a new frame in your future, whether it's a clear coat problem or something more serious.
Yep, that's what I've done. Fingers-crossed.
 
#15 ·
Got a reply from the manufacturer after receiving the digital pics of the frame. Here's what they said:

"Dear Mike,

the small air bubbles under clear coat aren´t worrying. It´s only an minor optical defect.
The reason could be too high air humidity at the painting process. Thereby the clear coat could become milky after a couple of weeks or months."


To which, I replied:

"Thank you for your quick reply concerning this matter!

Is this normal and can be expected on all XXX or only a small subset? Have you seen this issue before? Can you guarantee me that the this is 'optical' and will not have any 'structural' issues?

I specifically purchased the XXX (versus the YYY, or any of the competitions frames: Cervelo R3, etc.) because of the clear coat finish which showed the beautiful carbon weave underneath. I didn't want the carbon to be covered by paint, etc....I wanted to see it! If I knew this was going to be an issue, I would not have purchased the XXX.

I'm concerned by the fact that the air bubbles are spreading. What originally started-out as a small pea-sized section of air bubbles on the top tube a couple weeks ago, has started to extend down the side of top tube. Also, a second section has appeared further down the top tube from the first.

While it may be an optical defect, I'm sure you'd agree, it's not the quality I was expecting when I purchased the XXX, your top-of-the-line frame for 2007."



To which, they replied:

"I´m sure it´s an opitcal and not an structural defect. The carbon layers are okay.

This issue isn´t normal and it isn´t a special XXX problem. It could be happend at every carbon frame, but it´s really rare. I know another 2 cases only.

I´m agree with you this isn´t the quality of an high end frame. And you´re free to complain the frame about your dealer to XXX. We will replace the frame then, but I have no idea how long the process take."


I'm pushing for a new frameset....
 
#16 ·
You bet. Have your LBS start the process. You deserve a new frame.
 
#18 ·
1speed_Mike said:
Got a reply from the manufacturer after receiving the digital pics of the frame. Here's what they said:

"Dear Mike,

the small air bubbles under clear coat aren´t worrying. It´s only an minor optical defect.
The reason could be too high air humidity at the painting process. Thereby the clear coat could become milky after a couple of weeks or months."


To which, I replied:

"Thank you for your quick reply concerning this matter!

Is this normal and can be expected on all XXX or only a small subset? Have you seen this issue before? Can you guarantee me that the this is 'optical' and will not have any 'structural' issues?

I specifically purchased the XXX (versus the YYY, or any of the competitions frames: Cervelo R3, etc.) because of the clear coat finish which showed the beautiful carbon weave underneath. I didn't want the carbon to be covered by paint, etc....I wanted to see it! If I knew this was going to be an issue, I would not have purchased the XXX.

I'm concerned by the fact that the air bubbles are spreading. What originally started-out as a small pea-sized section of air bubbles on the top tube a couple weeks ago, has started to extend down the side of top tube. Also, a second section has appeared further down the top tube from the first.

While it may be an optical defect, I'm sure you'd agree, it's not the quality I was expecting when I purchased the XXX, your top-of-the-line frame for 2007."



To which, they replied:

"I´m sure it´s an opitcal and not an structural defect. The carbon layers are okay.

This issue isn´t normal and it isn´t a special XXX problem. It could be happend at every carbon frame, but it´s really rare. I know another 2 cases only.

I´m agree with you this isn´t the quality of an high end frame. And you´re free to complain the frame about your dealer to XXX. We will replace the frame then, but I have no idea how long the process take."


I'm pushing for a new frameset....
What's with this XXX crap??? What is it? - TF
 
#19 ·
1speed_Mike said:
Got a reply from the manufacturer after receiving the digital pics of the frame. Here's what they said:

"Dear Mike,

the small air bubbles under clear coat aren´t worrying. It´s only an minor optical defect.
The reason could be too high air humidity at the painting process. Thereby the clear coat could become milky after a couple of weeks or months."


To which, I replied:

"Thank you for your quick reply concerning this matter!

Is this normal and can be expected on all XXX or only a small subset? Have you seen this issue before? Can you guarantee me that the this is 'optical' and will not have any 'structural' issues?

I specifically purchased the XXX (versus the YYY, or any of the competitions frames: Cervelo R3, etc.) because of the clear coat finish which showed the beautiful carbon weave underneath. I didn't want the carbon to be covered by paint, etc....I wanted to see it! If I knew this was going to be an issue, I would not have purchased the XXX.

I'm concerned by the fact that the air bubbles are spreading. What originally started-out as a small pea-sized section of air bubbles on the top tube a couple weeks ago, has started to extend down the side of top tube. Also, a second section has appeared further down the top tube from the first.

While it may be an optical defect, I'm sure you'd agree, it's not the quality I was expecting when I purchased the XXX, your top-of-the-line frame for 2007."



To which, they replied:

"I´m sure it´s an opitcal and not an structural defect. The carbon layers are okay.

This issue isn´t normal and it isn´t a special XXX problem. It could be happend at every carbon frame, but it´s really rare. I know another 2 cases only.

I´m agree with you this isn´t the quality of an high end frame. And you´re free to complain the frame about your dealer to XXX. We will replace the frame then, but I have no idea how long the process take."


I'm pushing for a new frameset....
I guess it’s not a Cervelo R3? Is your bike in a Witness protection program? It would be nice to know what companies take care of these matters and which ones people have issues with.
 
#21 ·
My Guess Is Out-Gassing

I've been in polymer floor surfaces and chemical containment for 19 years. Epoxy biz for short. I have two guesses as to what your problem may be. I could be wrong on both but, I don't think so. The first is simply a contaminated spot on your frame where the clear coat didn't adhere. Hamburger grease or sushi on a worker's finger.

It could also be out gassing which is air trying to escape from a porous substrate through a non-breathing surface, your clear coat. This sometimes happens when we apply a thick coat of high viscosity epoxy to a concrete floor. What I would be worried about on your frame is the fact that there may be air pockets in the carbon lay up. NFG! Once the frame was exposed to sun light and warmed, air trapped in the carbon expanded and pushed to the surface. With some frames, the clear coat actually figures into the overall strength of the tube. Look, for instance, will void your warranty if you paint one of their frames because of the possibility of paint solvent attacking their surface. The bottom line is, there shouldn't be air trapped in your frame. That's the whole objective of Trek's OCLV (optimum compression, low void) process. Personally, I would not ride the frame in the photo, especially given where the bubbling is.
 
#22 ·
oily666 said:
I've been in polymer floor surfaces and chemical containment for 19 years. Epoxy biz for short. I have two guesses as to what your problem may be. I could be wrong on both but, I don't think so. The first is simply a contaminated spot on your frame where the clear coat didn't adhere. Hamburger grease
Hmm, frame was made in Hamburg, Germany! That's got to be it! :p

It could also be out gassing which is air trying to escape from a porous substrate through a non-breathing surface, your clear coat. This sometimes happens when we apply a thick coat of high viscosity epoxy to a concrete floor. What I would be worried about on your frame is the fact that there may be air pockets in the carbon lay up. NFG! Once the frame was exposed to sun light and warmed, air trapped in the carbon expanded and pushed to the surface.
Yes, that's what I'm thinking happened, too.

With some frames, the clear coat actually figures into the overall strength of the tube. Look, for instance, will void your warranty if you paint one of their frames because of the possibility of paint solvent attacking their surface.
I'd agree, but I don't know specifically if this is what Stevens does on the SLC. I'd assume, due to the ultra-lightweigth, it's intended to add some strength.

The bottom line is, there shouldn't be air trapped in your frame. That's the whole objective of Trek's OCLV (optimum compression, low void) process. Personally, I would not ride the frame in the photo, especially given where the bubbling is.
Agreed! I won't be happy until I get a new frameset. Optical or structural, it's a problem and I don't want anything to do with it.
 
#23 ·
Glad I could help, Mike. Good luck. I'd be interested in knowing more about the manufacturer. If the came recommended, they probably put out a good product. You just ran into one of, maybe, a few whoop's that should never have been shipped. More over, they've probably eliminated the problem. Do they have a web site?
 
#24 ·
i've seen this before about in the motorcycle industry. it used to be a common problem when painting or clearcoating carbon. a friend had carbon-fiber bodywork and had it clearcoated. bubbles started forming here and there, and as someone else stated, it's trapped air, but when i've seen it, it was not from the carbon, but from the clearcoating process. in my friends case, it was strictly a visual issue and not a structural one. a mechanic saw it and said he'd seen dozen's of bodywork with simliar issues- but this was 10 years ago.
 
#26 ·
doowde said:
where does the word "clearcoat" come into the equation? Are you referring to all the epoxy as simply a "clearcoat" or another separate "clearcoat" layer that then gets put over the epoxy?
The carbon frame pictured has a layer of 'carbon weave' (carbon doesn't really look like that) and then a layer of clearcoat over that. Some claim that their clearcoat privides UV protection to the actual resin??? - TF
 
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