Corvette Fiberglass Repair - Plastic SurgeryGiving Your Corvette's Bodywork A Facelift Can Be Easier Than You Think From the March, 2011 issue of Vette By Steve Temple Photography by Steve Temple
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Since Corvette bodies are made of a different material than most other production cars, repairing minor damage can require alternative materials and techniques. While fiberglass and SMC (Sheet Molded Compound, which is found on later models) have the advantage of being rustproof, such composites are subject to their own sets of problems. These range from crazing (also called "spider webbing") to cracking, usually from a slight impact. More-severe or widespread body damage may require the complete replacement of large components-a job best left to a pro-so we'll limit our focus to minor damage that can be repaired right in your own driveway. We'll start with slight surface imperfections. If polishing and waxing isn't producing the smooth finish you'd like to see on your beloved Corvette, consider using 3M Scratch Remover, which is designed to minimize defects that don't penetrate the clearcoat (assuming your vehicle has a two-part urethane paint). This product is fairly simple to use, requiring only three separate steps and a common household drill. We tried the 3M product on a C5 that had a few scratches on it, and they all but disappeared. For cracks or crazing (the latter is usually seen on older fiberglass bodies), a type of adhesive called Plastex can repair a wide range of materials. In addition to fixing fiberglass or SMC, it can be used to fabricate small components, or even repair metal (using a slightly different version of the repair kit). The inventor of Plastex, Tim Lewis of G.T. Motorsports, has some pretty impressive credentials in chemical engineering. In addition to being trained at the Northrop Institute of Technology, he's worked on the adhesive tiles used on NASA's space shuttle, and he served as manager of Harrah's car collection. So he knows his way around composite materials and how to take care of fine automobiles. Using Plastex is a straightforward process, easier than working with resin and fiberglass. Unlike conventional resin and catalyst, for most repairs the mixing ratio doesn't have to be in precise proportions, as long as the powder is thoroughly saturated. Depending on the type of damage, Plastex powder can be used with or without the cloth included in the kit. It dries very quickly in a variety of weather conditions, so you can sand it and prep for paint in short order.  Fine scratches in the clearcoat...  Fine scratches in the clearcoat can make your Corvette's finish look like a road map. If buffing and polishing doesn't get them out, a more intensive approach might work-as long as the scratches don't penetrate to the color coat. A quick way to evaluate the depth of the scratch is to run your fingernail over it. If you can feel the scratch, but your fingernail doesn't catch, you can probably repair the damage with 3M Scratch Remover.  The 3M Scratch Removal System...  The 3M Scratch Removal System is a simple kit, consisting of a small abrasive pad, a buffing wheel, two polishing pads (one coarse, the other soft), and two 1-ounce packets (Rubbing Compound and Scratch Remover). Look closely, and you can spot the small white scratch between the two pads. John Balentine, who volunteered his C5 for this project, says his dog Missy was the culprit. (She isn't allowed in the garage anymore.)  After washing the affected...  After washing the affected area with soap and water, spray water on both the finish and the abrasive pad.  Even though the 3,000-grit...  Even though the 3,000-grit pad feels soft, rub gently on the scratch until a bit of foam appears. After about 10 seconds of rubbing, wipe off the slurry with a wet paper towel to see if the scratch has disappeared. Don't overdo it, as the clearcoat is not very thick.  The area being rubbed will...  The area being rubbed will dull slightly, depending on the angle of the light. The following steps will eliminate this discoloration.  Insert the buffing wheel into...  Insert the buffing wheel into a standard household drill (note that a variable-speed trigger makes it easier to control the speed of the buffing wheel, as it's important not to let it heat up). Next, squeeze a dab of 3M Rubbing Compound on the pad. To prevent splatter, smear the compound around manually before starting the drill.  Use only a light to medium...  Use only a light to medium pressure (enough to slightly compress the pad at a flat angle), and operate the drill at a slow to moderate speed. Overlap the area slightly until the compound begins to dry, using progressively lighter pressure.  Remove any residue with a...  Remove any residue with a clean, dry microfiber towel. Make sure there's no dirt or grit on your towels, or you'll just make things worse.  Switch out the pads (they...  Switch out the pads (they can be rinsed for re-use), and apply the 3M Scratch Remover to the black foam pad. This product is thinner than the compound, so use care when squeezing it out, or you'll get too much on the pad.  Again, first smear the liquid...  Again, first smear the liquid without turning on the drill; this will minimize splatter.  Using a low-speed setting,...  Using a low-speed setting, polish the compounded area, overlapping it slightly.  Buff the area with another...  Buff the area with another clean microfiber towel until the finish matches the surrounding paint. Look at the area from various angles to ensure that all the scratches and compound have been removed. Repeat the previous step if needed. Protect with a polish or wax as a final step.  Fine crazing-also known as...  Fine crazing-also known as "spider-webbing"-can occur in older fiberglass due to age, weathering, and slight impacts.  Plastex can be used to repair...  Plastex can be used to repair just about any type of Corvette panel, from traditional fiberglass to urethane to SMC. (Highly flexible parts might require using another type of Plastex kit.) This particular fender panel had a slight crack, but we bent it open more for purposes of illustration.  To ensure a good bond, start...  To ensure a good bond, start by roughing up the inner surface of the area to be repaired.  Apply painter's tape to the...  Apply painter's tape to the outside area of the crack or hole.  The Plastex kit consists of...  The Plastex kit consists of three bottles of acrylate powder (clear, white and black, and colored additives are available for matching hues), a liquid hardener (methyl acrylate monomer), and a special untreated, non-reactive fiberglass cloth, which can be used on larger repairs.  Applying the powder can be...  Applying the powder can be done in a couple different ways, depending on the type of repair. For smaller damage, or vertical surfaces, first squeeze some powder into a small cup (provided in the kit).  Pour the hardener into a smaller...  Pour the hardener into a smaller bottle, and cap it with an applicator tip.  Add a couple drops of hardener...  Add a couple drops of hardener to the powder, but don't saturate it completely, as you'll use the applicator tip to pick up a small droplet.  Place the droplet into the...  Place the droplet into the crack and let dry.  Alternatively, you can sprinkle...  Alternatively, you can sprinkle the powder directly into the crack or hole to be repaired (as long as it can be laid horizontally, so the powder doesn't fall out).  Saturate the powder thoroughly....  Saturate the powder thoroughly. You don't need to measure the ratio; just make sure it's wetted completely.  Allow the mixture to dry,...  Allow the mixture to dry, checking by touch after 15 minutes or so.  Remove the tape from the outer...  Remove the tape from the outer surface of the part.  Use a Dremel or other fine...  Use a Dremel or other fine grinder to create a groove in the surface. The following steps also apply to repairing crazing or surface cracks on fiberglass.  Apply powder (or wet droplets)...  Apply powder (or wet droplets) to the groove in the outer surface.  Make sure the powder is completely...  Make sure the powder is completely saturated with hardener.  Use a spreader to force the...  Use a spreader to force the mixture into the groove and even out the surface.  After the mixture dries, sand...  After the mixture dries, sand the surface evenly until smooth, and then prep for paint.
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