Dyed Fiberglass- Cosmetic Alternative to Carbon Fiber

Some of you who know me, know that I have a particular interest in composite construction and have done alot of projects over the years both professionally at Apex Designs and personally for my racing projects. Several weeks ago, I was approached by a medical related company looking for a way to "dress up" their current machine by using carbon fiber covers in place of their existing injection molded plastic parts. After meeting with them and seeing the complexity of the parts, I quoted the project based on pre-preg oven cure carbon because the parts had several features that would be difficult to achieve by wet layup and bagging- especially since these were parts whose sole purpose was to add cosmetic appeal. My pricing for tooling and parts per unit were considerably higher than they wanted to spend for a relatively low production figures (80 parts annually) and I could not even come close to the economy of the plastic injection molded parts currently being used. Even so, the company asked me to research other alternatives to get the carbon look.

I had heard of 'black dyed fiberglass' that some folks were using to acheive the carbon fiber look and that I understood to be considerably less expensive than carbon. I researched it on the net and found that Fiberglast stocks the material as a dry fabric for about $15 per sq yard- about 1/2 the price of real carbon but still quite a bit more expensive than the Rutan glass I love to work with from Aircraft Spruce. I called Fiberglast and spoke with one of thier technical sales reps who was very helpful in sending me comparison photos of parts made with the glass and parts made with real carbon. I decided to purchase some to experiment in hopes that I could find an economical solution for my medical friends.

The glass arrived and the first thing I noticed was that it did indeed look ALOT like real carbon material- the color was nearly identical to real carbon. I also noticed that the weave was considerably tighter than standard 2x2 #284 twill weave carbon. This probably contributed to the material's lack of pliabililty- by that I mean that it was very difficult to wrap the material over even 70 degrees onto adjacent surfaces of my test tooling. Normally, my Rutan bi-directional glass literally drapes over the tool with ease and will stay put during the layup until the part is bagged. Not the case here with the black glass. I had considerable difficulty getting the fabric to stay in place over any folded edge- even when orienting the fabric at 45 degrees to the fold line- a technique that works very well with glass and carbon over tight radiused parts. I had to use ALOT more epoxy than I liked to wet out the cloth and get it to stick to the tool long enough for me to insert it in the bag and begin curing. (the epoxy used was the room temp cure West System #105 and #205 Hardener)

I let the part cure - 5 hours under vacuum, and then overnight before releasing it from the tool. With the amount of epoxy that went into the layup process, I was expecting to see a very nice smooth finish from the tooled side of the part but that was not the case here. The part had considerable voids in the corners of the weave- hundreds of tiny voids that gave the part a speckled appearance and that would be very difficult to correct even with heavy clear coating and sanding. The other interesting result was the the finished side's color was so much darker than real carbon that you could hardly even see the weave pattern- it looked more like a painted black panel.

I spent several hours clear coating, sanding and polishing the part and was never able to achieve a finish that I would ever allow coming out of my shop. I showed the real carbon sample and the black fiberglass sample to my medical friends, and they concurred with my assessment.

In conclusion, its my opinion that the black fiberglass material is not a good substitute for real carbon - especially since it's intent is primarily cosmetic. The black glass is only 1/2 the cost of real carbon, doesnt wet out very well because of its tight weave, and is too stiff a fabric to build much more than flat panels. Bottom line, if you are looking for a carbon alterative, this is not it. I would be very interested in finding people who have had success with this material, perhaps my methodology could be tuned to aid in the success of using this material.

-Steve