By jameslawson - 1/2/2025 3:19:55 AM
Recently I imported a few completely carbon car trims, these are not the typical cheaper carbon/fiber glass pieces that you see the Asia market often exporting.
One thing I spotted however is that nearly all their pieces no matter which supplier you use has a faint blue'ish hue, almost like a cloudy appearance when you view it under direct sunlight and from acute angles. I have tried sanding this all the way back to the fabric however what I typically find is the fabric layer is exactly the same due to it soaking up the resin.
Is this a reaction from post curing, or generally poor grade resin? I can't quite understand why 90% of the manufacturers I have come across have this ''issue'' yet the odd one or two don't. Frustratingly the suppliers who have this cloudy resin often produce much higher quality cosmetic items than the ones with absolutely clear resin.
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By jameslawson - 12/16/2025 1:46:54 AM
Weird follow up I know, but I think I just figured out why most of the Asian imported products have this appearance.
I took delivery of a fiberglass reinforced carbon bonnet in summer along with a large inflatable spray booth to paint it. However I noticed the resin top coat was FULL of micro bubbles, so much so in direct sun light it looked dusty, you could hardly see the weave. As I didn't want to spend days fixing this I decided to just prep and paint it.
Fast forward a few weeks and after letting the primer/base/clear finish off gassing I noticed a patch in the middle looked much clearer than everywhere else around it. When I got up close I noticed it was a patch I had to prep a little more, I had sanded through the micro bubbles and made it visually clearer. Whilst 90% of people wouldn't spot this it ate away at me for 3 months until last week, I sanded the entire exposed carbon section and began noticing the resin they had used must be a polyester resin, versus epoxy. It's insanely hard to cut through the layers by hand, I had to use my rotary sander with some heavy force to make a difference, this is when I began to notice it stripped back in layers and when I wet the surface again those areas without sanding now appeared blue/milky compared to the sanded sections!
These photos show the lighter versus darker areas of where the resin began thinning out.
 
Painfully I took it as close to the edge without burning into the basecoat and then prepped the surface back to 800 ready for Spectral clear again.
This would also correspond to my issue with where the weave has sank a LOT, they built it as a v-weave bonnet and the middle join is constantly printing through all paints, I can only assume the polyester resin has a pretty low temperature rating.
But yeah there we go, I can only assume polyester resin is cheaper in their market and easier to work with versus epoxy.
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