09c - CARBON FIBER OVERLAY / WRAP

When you can’t afford to go through the process of making molds off of an existing part, wrapping the part in carbon fiber is always an option. This of course is only for cosmetics and is often considered “blasphemous” to true carbon fiber nerds. Instead of making a part lighter from carbon fiber, you make it heavier by adding carbon fiber. Needless to say, the part is going to look great and 99.9% of people will have no clue that it is only wrapped in carbon fiber. In this blog we will walk through the steps required to wrap a pair of canards in carbon fiber.

Examine the Parts

The parts provided where fiberglass canards for an EVO. As you can see in the picture below, they are painted white and have a smooth surface finish. Prior to starting the carbon wrap, it will be important to do some surface prep. In addition, do note the many different surface orientations. This part has vertical walls, horizontal walls, and a top and bottom side. All surfaces need to be finished surfaces so we can’t hide the seam on an underside. This means that these parts are going to take some considerable work to complete! Consider this an “Expert” wrap job. I would start on a simpler part if you are considering a wrap project yourself.

Surface Prep

There are a few things to consider before performing a carbon fiber wrap on a part:
First, is the part smooth?If the part has too smooth of a surface finish the carbon fiber may not stick to it. If this is the case, sand the surface with a low grit sandpaper (~80 grit). Make sure all bonding surfaces are sufficiently scuffed.
Second, what color is the surface? Because you will be using a single layer of carbon fiber to wrap the part, there is the possibility that the original part will show through. To prevent this from being visible, be sure to spray paint the original part black before starting.

Third, how will the carbon be attached prior to the resin curing?In most cases, a simple spray adhesive will work to adhere the dry carbon fiber to the part before resin is added. However, as resin is applied, the spray adhesive will dissolve and lose its tackiness. As this occurs some surfaces may release from the part and the result can be unsightly bumps across the surface. An alternative to spray adhesive is a fast drying epoxy. Painting the original part with epoxy and letting it cure to a nice tack before applying the carbon fiber is one of the best options. The use of an epoxy compatible gelcoat also works well, especially if you can find a black gelcoat that will work as your spray paint and your adhesive.

Wrap the Part

After selecting the adhesive to use on your part (spray adhesive, epoxy, or black gelcoat), you are ready to wrap your part. This portion of the project requires the most finesse. You want to ensure that the fibers are straight and all edges are fully wrapped. In a complex part like this one, determine where you will hide the seam. The seam on these parts was placed on the bottom. Also, always start on the most important (visible) surface. Once that surface has been stuck you can fold, cut, and wrap to complete the rest of the surfaces.

If you are good at wrapping Christmas presents then you will likely excel at this process as well. Cut slits in the carbon where it is needed for it to deform to wrap your part. Once again, try to finish all edges on the underside of the part. Extra spray adhesive/epoxy can be used to adhere flaps to the underside.

Apply the Resin

Now begins the hard part. On a part like this one, you have to choose a side to start applying resin to. Use a foam or bristle brush to fully coat as much of the carbon fiber as possible. When applying the first layer, there is guaranteed to be a texture on the surface; don’t worry about trying to eliminate it all on the first pass. Doing a carbon wrap typically requires at least three layers of resin.

After the first layer has cured, rotate the part to apply resin to the next side. You will find it is much easier to apply a thick layer of resin to a horizontal surface, then a vertical surface. Once you have applied the resin, feel free to blow some hot air over the part to increase the curing process. On a part with four perpendicular surfaces, you can expect to need to complete 12 different resin applications. Without a heater, the time adds up quickly!

As resin is applied, layer after layer, you will likely notice bubbles forming in the resin. This is completely expected, but it is preventable! Use a heat gun on low to expand and pop these bubbles under the surface of the resin. The result is a glass-like finish clear of voids. Do be carful to not get the resin too hot as it can start to cure prematurely. This is one of the most important tricks to making a carbon fiber wrapped part look good.

Wet Sanding

Once enough layers of resin have been built up and there is no longer any carbon fiber weave texture, the part is ready to be wet sanded to its final state. Start at a lower grit (~220) to ensure the part is flat without any pumps. Do be careful to not sand through the resin into the carbon. When wet sanding the water should appear white and milky. If it turns dark and black, this means you have sanded too deep and are in the carbon. If you sand too deep into the carbon you may distort the weave, or worse, go straight through it. If this is the case, you will need to add another layer of resin.

Assuming you don’t have to add more resin, continue to wet sand as you step through your grits. Before stepping up to a higher grit, ensure all scratches from the previous grit have been removed. I would recommend the following grits: 220 – 400 – 600 – 800 – 1,000 – 1,500 – 2,000. After reaching 2,000 grit you are ready to buff and polish the parts! See ourBuffing & Polishing posts to help perfect your technique! If you want an added level of UV protection you may want to spray the part in a layer of automotive clear coat to prevent yellowing of the epoxy resin. The parts pictured below are shown pre-clear coat.

Do note that this is not as easy of a process as it sounds. It is certainly cheaper than making a custom mold, but it does require many hours of hand labor to perfect. If paying a shop to do this, it could actually cost just as much as making a mold depending on their rate. Carbon wraps also have other downsides. Epoxy resin is not meant to be built up like this and you could find your self with odd surface anomalies. Amine blush is commonly experienced when wrapping a carbon fiber part. Amine blush presents itself as a milky appearance within the resin and is caused by the presence of moisture in the air during the cure. To prevent this, it is best for resin to cure in a vacuum, but this can’t always be achieved when wrapping a part. To minimize the risks, consider only doing a process like this on a hot day when the humidity is low.

Install and Enjoy

Thanks to our friend Sherwin for sponsoring this project! Below is the final result with the canards installed on his EVO. This is just one small part of his complete rebuild!