Composite Panels Classroom-- Car Craft Magazine

Here’s what makes it all happen. A composite material is composed of a matrix material and a reinforcement material. Carbon fiber uses woven strands of carbon as the reinforcement and an epoxy as the matrix. The carbon reinforcement carries most of the load burden when the material is bent and stretched, and the epoxy transfers the load from fiber to fiber to evenly distribute that load. Some composites use a thermosetting polymer as a matrix material and must be oven-baked to cure, but the epoxy we used cures with a liquid hardener.
Here’s what makes it all happen. A composite material is composed of a matrix materia
First, clear a large, clean work space. You want it as spotless as possible; trapped dust and dirt look pretty lame in composite panels. Preparing the mold is simple when you’re fabricating flat panels. We placed our glass sheet on a table, then sprayed it with glass cleaner to make sure it was clean. The next step is to apply the mold release so the carbon won’t stick to the mold after it’s cured. Apply the release in a swirl pattern, like you’re waxing a car, and buff off the haze after it dries. For a new mold, repeat the waxing process at least 4 times. On the final coat, buff the glass as if you were detailing a 100-point show car, because every imperfection (including dried wax residue) will show up in the carbon’s surface. Preparing a good mold is the key to turning out flawless panels.
First, clear a large, clean work space. You want it as spotless as possible; trapped dust

Unroll as much carbon cloth as you need. Be sure to allow for 2 inches of extra cloth in every direction, because the fiber strands on the edges are likely to distort—you’ll want to trim those edges off after the panel has cured. Lay out the piece you want to cut with low-tack masking tape. Keep in mind that you can cut the carbon at either 90- or 45-degree angles (on a bias). Bias cuts look cooler but usually waste more material—it’s your choice. Cut down the center of the tape lines so the carbon strands don’t unravel. Even with the low-tack tape, we still pulled off the outer two strands of carbon when we removed the tape after cutting out the cloth. That’s why we recommend you cut extra material! Unroll some of the clear plastic sheet and cut out a piece that’s approximately 1 foot larger in all directions than your carbon. Lay the carbon flat on top of this plastic sheet.
Unroll as much carbon cloth as you need. Be sure to allow for 2 inches of extra cloth in e
A good rule of thumb when mixing the epoxy/hardener is to use one part epoxy to one part carbon cloth, by weight. We didn’t have an accurate scale around the shop, but fortunately there’s an approximation that makes measuring easier: 1 fluid ounce (volume) of epoxy weighs about 1 ounce. We bought a few disposable graduated measuring cups from U.S. Composites, so it was easy to measure the epoxy in fluid ounces. The carbon cloth we purchased was 5.7 ounces (weight) per square yard. We cut a 10x10-inch piece of carbon, and although we didn’t have a scale, we were able to calculate its weight by knowing a square yard of this material weighed 5.7 ounces.
A good rule of thumb when mixing the epoxy/hardener is to use one part epoxy to one part c
Using this equation, our carbon piece weighed 0.44 ounce, so we combined 0.33 fluid ounce of epoxy with 0.11 fluid ounce of hardener (three parts epoxy to one part hardener). Stir the epoxy for a few minutes.
Using this equation, our carbon piece weighed 0.44 ounce, so we combined 0.33 fluid

Pour some of the epoxy onto the carbon cloth that you laid on the plastic sheet. Use the Bondo squeegee to carefully saturate the carbon with epoxy, spreading the epoxy from the center of the carbon to the edges. Add the rest of the epoxy and squeegee until the carbon is completely smooth and “wet” with epoxy. Carry the carbon and the plastic sheet over to your glass mold, flip it over on the glass (carbon-side down), and continue to squeegee the carbon through the plastic sheet.
Pour some of the epoxy onto the carbon cloth that you laid on the plastic sheet. Use the B
Carefully peel the plastic sheet off the carbon, and squeegee off the excess epoxy, making sure there aren’t any dry areas on the carbon. Any dry spots or air bubbles will appear as “pinholes” in the finished carbon panel, so take your time. Let the epoxy dry (this will take a few hours—we came back the next morning to finish the project).
Carefully peel the plastic sheet off the carbon, and squeegee off the excess epoxy, making
You have a few options when it comes to reinforcing the carbon-fiber layer. “Sandwich core” construction is the most rigid reinforcement. This involves a layer of fibrous material sandwiched between the carbon outer layer and a fiberglass backing. We didn’t need a panel that was very rigid (we built a radio block off-plate/ switch panel for our Chevelle), so instead we opted to laminate the back of the carbon with two layers of fiberglass weave. The finished panel is plenty strong, but not as rigid as a sandwich-core construction. Lay out and cut two or more pieces of fiberglass using the low-tack masking tape, so each piece is the same size as the carbon fiber. We cut each fiberglass piece at a slightly different bias so the weaves were at different angles. This adds panel strength because the fibers “pull” in more directions when the panel is loaded.
You have a few options when it comes to reinforcing the carbon-fiber layer. “Sandwich

The fiberglass cloth also gets saturated with epoxy in the same proportion as the carbon cloth (1:1 by weight). Measure and mix the correct amount of epoxy and hardener and place your fiberglass cloth atop another piece of plastic sheet. Before you transfer the ’glass onto the dry carbon-fiber sheet, wet the carbon with a little epoxy to help the ’glass stick to it. Then flip the plastic sheet over and transfer the fiberglass onto the carbon fiber. Squeegee in the same manner as you did the carbon fiber. Let the ’glass dry, and repeat the process with your other fiberglass layer(s).
The fiberglass cloth also gets saturated with epoxy in the same proportion as the carbon c
After all the laminates are applied and everything has dried, it’s time to reap the rewards of your work! Pop the carbon fiber panel off the glass mold. We needed to use a razor blade to “encourage” the carbon to come off the glass, but the panel came off without incident (this is why we applied five coats of mold release). The panel looks awesome, and it’s amazingly resilient and strong. We trimmed it with a sheetmetal shear, but it’s possible to cut these thin panels with scissors if you’re careful. Larger panels require a cutoff wheel or the like, but use respiratory protection and wear gloves because the dust is downright nasty. Don’t even think of grinding on your panel near open flames, because the airborne carbon dust will ignite!
After all the laminates are applied and everything has dried, it’s time to reap the r

Bet you never dreamed youd see a carbon-fiber how-to story in the pages of Car Craft! Dont worry; we havent fallen victim to the import craze, and were certainly not going high-buck on you. Were not totally clueless. We invested a total of $127 into this project, and we made some strong, light, and trick-looking carbon fiber panels in our garage. Care to read on?

Theres an aura surrounding composite panels that keeps them shrouded in mystery from most car guys. Certain composite-manufacturing processes do qualify as black arts, but laying up simple carbon-fiber panels doesnt require an advanced degree or an enormous pile of cash.

We kept the panel design simple for this story because it was our first crack at fabricating carbon fiber. Learning to lay up flat panels is the best way to start because theres no need for a complicated moldall you need is a clean and scratch-free piece of glass. Guided by the information in this story, you can create a set of door panels or a switch/gauge panel for that sexy street machine in your life. Thanks in part to help from Ivan Nausieda (proof that younger brothers are good for something), this project turned out so well that were planning to make a carbon dash cluster for our Chevelle. Well be sure to show you that project in the futureprovided we can make it look as good as these flat panels.