Painting The Factory Five Cobra Jet Challenge Car

Painting FFR_edited-1

As with any specialty-built custom, our Cobra Jet Challenge Car would never be complete without a stunning exterior finish, something to set it apart from any factory-fresh hue and give the car true presence. Snakes are known both for their mixtures of colorful patterns warning of toxicity, and their muted shades to slither subtly — camouflaged from detection.

Project FFR Cobra Jet has both the bite and the bark to back up its namesake — now it’s time to look the part. To achieve the effect we were shooting for, we opted to blend a custom mix of pigments, pearls, and clears. Turning to the specialists at Sherwin Williams for excellent materials, and the deft hands of Sergio Cantu of 3rd Gear Customs, we settled on a finish that suits the car in the way it was envisioned.


“Painting is easy — you can ask any body man, the last five minutes, and the very last coat is what matters. Everything up to that is a buildup of either success, or total failure,” Cantu prefaced his story. “The main challenge we had was trying to make sure the fiberglass mold was fit perfect. When Factory Five sent over the mold it was on a horse — fiberglass flexes — and it flexed a lot so we had to do this in stages,” he continued.

Don’t Look A Gift Snake In The Mouth

Fiberglass is a composite material, meaning that it is a combination of elements that each lend a characteristic toward the final product. Woven fiberglass cloth is impregnated with a catalyzed resin which cures into a polymer. Without the cloth the resin is brittle, and without the resin the cloth is flimsy. In the end we are really working with plastic — so flexibility is a characteristic to work around.

“The first stage was to get me the car on the actual chassis, because if I fit all the doors, the hood, and the trunk on a horse where it allows the fiberglass to hang, when we put it on the car it would be completely wrong,” illustrated Cantu.

20150730_160240_HDRWith the car on the chassis Cantu set forth to bring the body work into focus. Embodying the spirit of this build as a true grassroots kit, he would continue the work started by owner Mark Gearhart, in his own garage. Several specialty considerations came into play as Cantu circled the bare body, because this FFR Cobra Jet is a Challenge Car version, an extensive roll cage winds through the cab to encapsulate its occupants.

Cantu first made relief cuts where the cage interfered with the traditional body lines — through the doors, turtle deck and other contact spots. Next Cantu set to establishing show car-quality panel gaps, and door jambs.

Using tape lines as boundaries up to where he cut, Cantu established extremely tight panel gaps.

“I knew we weren’t using rubber gaskets so I took it on my own to say, ‘we are going to have much tighter tolerances.’ A lot of people don’t realize when you have a jig and butt two pieces of fiberglass together they lay a fiberglass seam filler along the joint. You can finish this surface one of two ways — you can sand it flat and risk air pockets being underneath, or cut it all out,” Cantu proposed.

20150917_150740_HDRWishing to deliver only the highest quality for a SEMA-bound custom, Cantu was not about to cut corners here. “I dug out all of that junk, all across the seams — I ended up using Duraglass — it’s like fiberglass powder thrown into Bondo. Just in this process alone, I had about 200 hours — all hand blocking. There is no machine that can do this kind of work. It got very thin in some places, so it was a very scary situation where I had to be careful not to break any of those bonds,” Cantu recalled.

The joints were ground down and refilled with Duraglass to prevent any future defects.

Achieving a perfect finish on any composite part is a challenge due to the process by which they are fundamentally made. Layers of cloth and resin forced against a mold with a plug are not immune to air pockets and pin holes. Gel coat that lines the female mold helps to minimize the occurrence of defects but some inevitably escape. After Cantu chased down all the pin holes with a metal roller meant for scoring paper he could move away from the messiest of the body work.

Sherwin Williams Automotive Brings Color To Our Project

We talked to Sherwin Williams product manager Kyle Hauenstein for some background on the products we used finishing project FFR Cobra Jet. Water-born paints are the future for us builders, but that doesn’t mean despair, low VOC (volatile organic compound) applications exist and perform comparably to old school catalyzed paints.

“A few things that make our water-born base coat “AWX” are it’s versatility, they dry quickly, fast flash times, great coverage, and a good color match — if you have a target you can get to it pretty easily,” Hauenstein explained.20160224_105902_HDR1

This build has been featured as a true do-it-yourself project, working in garages and drive ways. Sherwin Williams appreciates the needs of the home builder and that shows in their products.

“Anytime you’re spraying base-coat/clear-coat as a do-it-yourselfer that can be challenging, it is nice to have a product that can dry quickly if you want it to, you could get this done in a couple days. Some of the capabilities we have for our end users to look up colors through our online retrieval system are really nice, it’s called Formula Express 2.0,” Hauenstein continued.

Priming The Surface

20151010_143107_HDR“Then we get into the primer stage — and this isn’t just normal primer, it’s the primer Sherwin Williams provided. There’s one primer that can be used for multiple things, it’s P27 — it can be used for a speed primer if you are in a rush, it can be used as a heavy fill primer ready to block in 24 hours, and it can also be converted into a sealer, and you can use it direct to metal,” detailed Cantu.

“P27 for low-VOC markets, and P30 for other places are probably the most well known products we have — just because of the flexibility that it has. Most primers are just gray, black or white — this one you can mix to get over 150 colors. You could mix this to get whatever color you need to help get coverage — which is great in a production environment but also for a do-it-yourselfer,” Hauenstein added.

20151010_143119_HDRBy using the three different types of reducers this versatile primer replaces the need to source different primers to suit each task. Although one consideration to keep in mind is that while the different reducers may yield different primers, the color will remain the same. Spraying one layer over another may benefit from a little tinting to differentiate the coats.

In the midst of panel fitting and blocking we encountered a challenge with the provided hood scoop. As in most cars, the drivetrain does not run down the exact centerline of the car — and by extension neither does the induction system. An asymmetrical hood scoop might be fine if this was a cubist interpretation of a 1960’s roadster but for our build something special needed to be done.


Two scoops were combined and centered on the hood (not over the opening) to preserve aesthetics.

Taking two standard hood scoops Cantu was able to split them off-center and graft them together to create a larger scoop. Simultaneously we enlarged the opening in the fiberglass hood to accommodate the carbon fiber circle track K&N air filter.

“With that we went to heavy blocking, I think I put three coats on so I could get it blocked out and perfectly straight — then I went to the underside of the car and we smoothed out some of the edges,” Cantu explained.

With the car fully smoothed and primed there was yet more sanding and smoothing to lay the ground work for the flawless paint job we were after. “After the final primer coat I started wet sanding. In order to get the final finish of how slick the color is now with the matte, the pearl, and the metallic — this is where the process starts. If this doesn’t start out slick it’s like a ripple that gets worse, and worse, and worse — if you have a little bit of orange peel in the beginning, in the very end it’s going to be terrible,” Cantu emphasized.


Extensive blocking and wet sanding were required to smooth the surface. Exposed (red) gel coat areas had to be re-primed to promote paint adhesion.

“We went in with the base — this is a water-born color that I mixed, I had some green pearls, and some blue pearls. I like to think of the color as like a pencil lead light and gray in some lighting and dark in others,” Cantu relayed sentimentally.

Mixing The Perfect Ratio


The ratio to achieve this satin finish was labor intensive to discover, but ultimately favored a matte clear to gloss almost 10:1.

“Every color, whether it’s solvent-based, or water-born-based, they all dry matte — so you have to put some sort of finish on them. I put four layers of clear down, then I cut and buffed it, got every bit of trash out so it was perfectly slick — zero orange peel, ready for me to come back in 24 hours with my clear mixture to drop one coat. If I start painting first thing in the morning I have sealer coat, base coat, and clear coat floating in the air, and they will settle. By coming in first thing in the morning, wet sanding, and shooting one coat, there’s going to be zero movement in the air and you’ll get a perfect finish,” Cantu theorized.

20151021_105724_HDR“To get it down to where it wasn’t a matte finish It took me about eight tries to figure it out, I basically went down to a 9:1 ratio. Nine parts matte to less than one part of gloss. Even though I only used two quarts, I mixed two gallons just to get it right because I had to find that little bit of ratio,” he continued.

“A lot of the time when you get reduced-gloss finishes pre-packaged it’s very difficult to keep that consistency throughout the product — we like to give our customers an opportunity o mix it on site. We’ve done a lot of due-diligence behind the scenes to say you need this percentage of flattener to get this sheen,” Hauenstein identified.

Cantu was new to using Sherwin Williams products, having sprayed another mainstream brand for years. He explained to us that the transition was amazingly easy, and that he is a Sherwin Williams guy from here on out!

“They were so easy to get a hold of, making the switch to Sherwin Williams easy in the sense that their data sheets were so specific, and they have so many tech reps I could get them on the phone nearly 24 hours a day,” Cantu explained appreciatively.20151021_105720_HDR

Wielding pinches of colorful pearls and hovering over a paint mixer like an alchemist to a caldron, Cantu concocted a blend to turn this pencil lead gray into an subtly iridescent green and gold.

“The final top coat was just a dusting of the pearl — that way it’s not too prominent and in your face. It was just something I did by eyeball, it took me six hours to get it right and it was a six-hour gamble because I was not sure Mark was going to like it. I think I nailed it with a 3rd Gear Customs twist — it comes easy to me, I love pearls — but you have to pick the right ones,” Cantu concluded.

Five Things You Should Know When Prepping Your FFR Roadster With Sergio Cantu

  • Make sure you fit the body and all the panels on the chassis, not on the horse.
  • Determine if you are going to be using fixed pieces like gaskets and hinges.
  • Make sure you get all the air pockets out of the gel coat. You never know when those are going to come back; don’t cut corners.
  • After blocking, turn the body upside down to look for any thin or light spots to reinforce.
  • You must use quality products.

The end result of Project FFR Cobra Jet is a graphite hue that exudes a warm brilliance. Accented by the iridescence of green and blue pearls this car embodies the reptilian appearance its name suggests. Different lighting conditions vastly alter the perceived color — from very dark to nearly silver, and Cantu’s pencil lead analogy certainly applies. Mixing a color and a surface finish as unique as this makes it nearly un-reproducible.

Making tiny incremental adjustments to achieve the desired effect and going by an artist’s eye means calculations and recipes get muddled. We are thrilled the end result stands up to the caliber of this project. Stay tuned for final installments of the build!

Screen Shot 2016-02-04 at 9.45.37 AM copy

Cantu’s favorite shot of the paint job, highlighting the pearls reflective quality and colors.

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About the author

Trevor Anderson

Trevor Anderson comes from an eclectic background of technical and creative disciplines. His first racing love can be found in the deserts of Baja California. In 2012 he won the SCORE Baja 1000 driving solo from Ensenada to La Paz in an aircooled VW. Trevor is engaged with hands-on skill sets such as fabrication and engine building, but also the theoretical discussion of design and technology. Trevor has a private pilot's license and is pursuing an MFA in fine art - specifically researching the aesthetics of machines, high performance materials and their social importance to enthusiast culture.
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