I was hoping for some help. We are producing a carbon and fiberglass laminate part. The carbon weave is standard plain weave and when held up to the light, light shows through the weave. We have heard that some type of urethane film had been used to solve this is. Does anyone know what this might be? We have tried dyes with mixed results. If anyone know a dye that works well with high viscosity epoxy that would be great to know as well.
Thanks in advance,
Richard Davis
Using a clear epoxy resin? Add graphite powder to make it black. And as a bonus you’ll get a higher: Tg, stiffness, hardness, toughness, and wear resistance.
You can always shoot the back of part with black paint.
What is the thickness of the part?
I make some sheets with 1 layer of 200 gr carbon and 1 of 500 gr glass. I impregnate carbon with pure resin, glass with resin + black pigment. Or i paint black sprye color on glass after cured
Another thing to consider, assuming the job doesn’t specifically call for a particular weight of carbon, is using a heavier weight weave.
Most people use 5.7 ounce, but by simply stepping up to 6 ounce, it’ll give you a more fill look, while leaving the weave less room to move.
I wouldn’t go so far as to call the weave “tighter”, but it definitely helped solve some of the issues we had early in development.
Painting, as Wyowindworks mentioned, is also a reasonable solution.
Hope this helps. 
Or you can use carbon fiber that has more Density pics (weaves) per inch, instead of using 12x12(Most common for 2X2 Twill Weave 5.7-6.0) oz carbon fiber, you could use 14x14, or 17x17.
Another possibility is to use a black dyed polyester veil behind the carbon. There are even carbon veils if needed.