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Prep And Paint Guide - Major Makeover

How To Prep And Paint Your Corvette

Steve Dulcich May 27, 2010
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There are many things that separate an average Corvette from the standout cars that make people turn their heads and take notice. The overall paint finish ranks right up at the top of what counts when it comes to the visual statement that speaks loudest. No matter how worthy your machine might be in other qualities, it's the paintwork that makes the first impression, whether rolling down the road or under scrutiny on the show field. In fact, often the key feature a car is judged by is the appearance of the paint. How often is a car described disparagingly as a 20-footer, meaning that it might look good from 20 feet away, but falls short under closer scrutiny?

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A fine paint job shows the level of craftsmanship as it is approached for a closer look. While the 20-footer might be a disappointment as you get closer and see the flaws, blemishes, and shoddiness of the paint, a great paint job will only draw admirers in. It takes a dedication to quality and an uncompromising eye for detail to achieve a fantastic show-quality paintjob, and that starts from step one-the body.

Get Professional Help or DIY?
One of the first things to contemplate when staring at your Corvette project and dreaming about perfect paint is what, if anything, you will tackle yourself. Here it's important to take into account your previous experience and level of skill, the equipment at hand, and perhaps most importantly, your own level of perseverance. Make no mistake, body restoration and paint is one of the most labor-intensive endeavors you'll ever encounter, and messy work at that. Expert paint and bodywork is very expensive, and it's tempting to save some of that costly work with a little (or a lot) of sweat-equity. However, it is also all too easy to get in over your head, or end up with results that fall far short of your dream of that fantastic paintjob. We've known do-it-yourself auto hobbyists that have succeeded in major body panel replacement and repair, and taken the project to completion with stunning paintwork, all in their own garages. We've also seen enthusiastic but botched attempts at the same that resulted in perpetually unfinished projects, and more work for the professionals that finally took over. What's important here is to be realistic in qualifying your own skill levels when deciding whether to tackle some aspects of a paint project, or just turn it over to the pros.

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The overwhelming majority of domestic vehicles relied on stamped steel body structures, while the Corvette body has always been manufactured from composite fiberglass material. This material takes a whole different set of rules when it comes to every level of repair and prep in comparison to a more common steel vehicle. Fiberglass is far softer, and unlike steel, it breathes, while reacting to chemicals and solvents differently. Steel will dent like a tin can, while 'glass will shatter and crack. The hammers, dollies, torches, and welders of a typical bodyman's toolbox are useless when considering Corvette repair. In their stead are techniques of fiberglass layup, cutting, and bonding. The bottom line here is there are auto bodymen, and there are Corvette bodymen. While there certainly are some very talented individuals out there with the skills to handle both, for the most part when considering having work done to your Corvette, it pays to seek out those who specialize in our plastic-bodied machines.

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Whether you plan on taking on the whole task of painting your car yourself, or placing it in the experienced hands of an expert, it's worthwhile to understand exactly what's involved in getting the job done. We'll go through all of the major steps in taking a car through the body and paint process, from beginning to end.

Difficulty: 3 Wrenches

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Virtually any repaint other than a bottom-of-the-barrel, mask-and-blast job is going to require some level of disassembly. The amount of disassembly can vary considerably, from just removing some of the exterior trim, to a full frame-off, total strip-down to the bare body. Naturally, the scope of the project is going to dictate the extent of the teardown to some extent, as will the condition of the vehicle to begin with. If the goal is a national-level restoration or show car, a complete disassembly is generally required. On the other hand, if a good presentable daily driver is the goal, very respectable results can come from a minor partial disassembly. When contemplating how far to go, it's important to keep in mind that it will take many times longer to reassemble the vehicle than it did to take it apart. Overly ambitious disassembly has led to many failed project attempts.

There's no denying that the further the vehicle is disassembled, the more detailed the final results. Removing the bolt-on body panels provides a level of access for refinishing the jamb areas that simply cannot be matched with the panels installed. Removing the bumpers will allow perfect paint coverage in the filler areas behind, while removing trim and handles will give a seamless finish. Removing moldings, weatherstrips, hinges, latches, lights, and the like allows full paint coverage in the blind, hidden, and covered areas for a seamless look, devoid of tell-tale tape lines, or worse yet, overspray where there should be none. Therein lays the balance-judging just how far to go with tearing the car down with the amount of time and effort that is added to the project. Just where this balance is struck will have everything to do with the quality of the final result.

Even in a driver quality repaint, the condition of the car will play a major role in the level of disassembly required. For instance, a problem such as sagging doors with worn hinges will probably require the doors be removed to repair the defective parts, increasing the scope of the disassembly. It's in these early stages of the paint and body project that problem areas need to be identified and corrected. Things like the panel fit of the doors, hood, and headlamp assemblies may require attention, which will lead to their removal during the body and paint process. Rubber items such as seals and weatherstrip may be deteriorated, so naturally they should be removed before proceeding with the paintwork.

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Whatever the extent of the teardown, it's imperative to have a system to organize and catalog the parts for reassembly. Boxing, bagging, and labeling are just as important here as the actual wrenching while taking the parts off. Photos are a very good way to provide a visual reference of how the various items removed go back together. A factory assembly manual is also a highly recommended reference. Keep in mind that a major paint project can take much longer than anticipated, and as time passes, it's going to be very difficult to remember where everything goes if the parts are all piled in a heap under the work bench.

Difficulty: 3 Wrenches

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As with disassembly, a decision is going to have to be made early on whether to completely strip the car's original paint. Again, the car's condition may very well dictate the required course of action here. The only situation in which the original paint can be retained is if it is sound and in good condition to serve as the base for a repaint. As is often the case, with the common acrylic lacquer paints used through to the 1980s, the original paint may be brittle, checked, and cracked, making it an unsuitable base for additional paint. Another common problem with older Corvettes is too many previous repaint and panel repairs. We have seen some cars with up to eight previous repaints, with an unbelievable paint film thickness as a result. This is usually the result of a succession of cheap paint jobs by previous owners, often with low quality materials. Again, this is a case of the current condition of the vehicle dictating what will need to be done; in this case stripping the paint.

There are several methods to remove old paint. Each have their advantages and disadvantages, though all the techniques we will discuss can be successfully employed to strip the car. The most basic technique is simply sanding the paint. This is very easy with a metal-bodied car, since the material removal essentially stops once the bare metal is reached. On a 'glass-bodied car such as a Corvette, the sandpaper will keep cutting right through the factory gel coat and through into the fiberglass. The bottom line here is that sanding can inflict serious damage to the body panels, digging in and creating waves and scars that were not there before. We have, however, seen experienced Corvette technicians strip a car using a common air-powered D/A (dual-action) autobody sander with no damage at all. Operator skill is the key between success and failure here.

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Another approach to stripping, which like sanding can be done by the home hobbyist, is chemical stripping. There are many brands and formulations of paint stripper on the market, some with harsh chemicals, and some newer environmentally friendly types. When contemplating a chemical stripper, be sure to use a product that is rated safe for fiberglass. Chemical strippers vary in their effectiveness and may take multiple applications to strip difficult or thick paint. Overall, for the do-it-yourselfer, chemical stripping is the favored technique. When using any chemical stripper, the manufacturer's instructions and precautions should be followed, and the material should be tested in a small contained area of the car's body to guard against an unexpected reaction with the panel. The chemicals and removed paint can be very messy, and care should be used to contain the used material. Normally, after chemical stripping, the panel surfaces will need to be thoroughly cleaned and neutralized, and the panels given a final detail sanding by hand.

Besides the above-discussed process of sanding, there are other mechanical means of paint removal that will work to strip the paint off your Corvette. Many Corvette enthusiasts and restorers will use a scraping technique, typically employing a razor blade on edge to literally scrape the paint off an inch strip at a time. With the right technique, scraping can be very effective and surprisingly quick, removing the paint without damage to the underlying panels. This is especially effective with the old and brittle original lacquer paints and primers. Of course, a sharp blade in the wrong hands has the potential to gouge and scar the panels, so caution is the watchword here.

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Blasting is yet another option for paint removal, but unlike the other techniques mentioned, it is generally done commercially. Many types of media are effective in removing paint without damage to the fiberglass below, making this a very viable option. When shopping for a commercial blasting establishment, look for a business that has had previous experience with Corvette bodywork. Blasting soft fiberglass should not be done using some of the harsher media often used on steel.

Difficulty: 3 Wrenches

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It has long been said in the classic car world that paint can hide a multitude of sins. Once the paint is stripped and your machine is sitting there in bare 'glass, it is all out in the open. This is really the point at which a true assessment of the condition of the body can be made. It's not uncommon to find some real problems that were hidden by the previous paint, and some can require very extensive repairs. Often these are botched or shortcut previous repairs, using improper materials or techniques. We've seen examples where every body panel turned out to be junk, hidden under multiple cheap repaints and bondo. These kinds of problems simply do not provide the solid foundation required when it comes to high-quality Corvette paintwork. Usually, these improper repairs, if neglected and simply painted over, will show through over time making it impossible to achieve a top-notch finish.

If major improper panel repairs are found under the paint, the best course of action will be to replace the full panel. It can be distressing to contemplate having to replace major body sections when all seemed relatively sound under the disguise of the old paint. The truth is, replacing the panel is definitely the superior alternative, and is actually quicker and easier than a partial panel repair or patching the damaged piece back together.

Even a Corvette body in relatively good condition will typically have minor structural problems and flaws, such as stress cracks, or even surface webbing in the fiberglass itself. Fiberglass simply is not tolerant of surface bending stress and flexing, especially over time, creating these flaws. It is important to identify these areas through a very careful and detailed inspection of the surface. While the smaller examples of these kinds of distresses in the fiberglass will temporarily be filled with primer and seem to disappear with fresh paint, the damage will usually begin to show through with time.

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A Corvette body panel that is visibly in good overall condition can still have small or minute stress cracks and 'glass damage that can be very difficult to identify while the surface is in bare fiberglass. These small imperfections have the potential to surface later, once the new paint has fully cured and the panel surface is once again stressed in use. A technique for finding these flaws is to wipe the surface down with a wax and grease removing paint prep solvent, and carefully examining the surface as the solvent evaporates. The solvent will collect in minute cracks and breaks in the surface, identifying minor flaws, breaks, or cracks that can pose problems if not addressed.

Difficulty: 4 Wrenches

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Fiberglass body repair is a skilled trade onto itself, and here the professional Corvette bodyman distinguishes his ability from a regular steel car guy. The temptation for a novice is to simply "mud" a damaged panel with filler and call it a day. The problem with these kinds of repairs is that body filler has very poor structural strength, and stresses will work through a filler repair, eventually showing the original damage through the new paint.

Body panel work on Corvettes comes in two main categories-panel repair and panel replacement. Here, a decision has to be made on the best course of action in effectuating a strong and long-lasting repair, and it is a judgment call. Sometimes it's easy to evaluate what is needed, letting the condition of the panel dictate the correct approach. A panel with minor flaws and some surface splitting, but in otherwise good condition, is easily repairable. These small flawed areas are sanded, and the trouble spot can be reinforced with a thin layup of fiberglass mat and resin. Once cured, the area is sanded smooth and then filled and blended with a light skim of body filler. The added fiberglass will add structural strength to the surface of the repair. Deeper or structural cracks can often be similarly repaired, with the best chance of success involving grinding the front and back of the panel and laying up the fiberglass on both sides.

Working with fiberglass is not too difficult to master with a little practice, especially in smaller, contained areas. The fiberglass mat material is cut to form a patch on the required shape with ordinary scissors, and then a batch of resin is mixed with the activator. Using a short bristle brush, the resin is applied to the mat to saturate it, and then it's applied to the surface. There are many little tricks and techniques that can be used in applying the repair mat. The repair area of the panel can be pre-wet with activated resin to better accept the repair mat. Once the patch is in place, it can be covered with ordinary plastic wrap and a brush or roller can be used over the top to roll out excess resin and/or air bubbles. A good application of fiberglass will not have excess resin or air inclusions.

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Panel Replacement
Difficulty: 4 Wrenches

Often, once a body panel is stripped of paint, we'll find a minefield of previous repairs that are not up to restoration standards. These can be previous accident damage repairs covering large areas of a panel, and sometimes the structural value of the repair work is very poor. In cases like this, it's best to consider panel replacement. New body panels are available from a variety of sources, and the advantage here is that the fiberglass is structurally sound. Corvette body panels are bonded in place, with the seams between various panels backed-up by bonding strips. Sometimes partial panels are used to make a repair to a portion of a body panel where the damage is localized; however, this will require an additional, non-original seam in the vehicle's body. These seams can create stress points and can even come back to show through the paint after the vehicle has been put back into service; however, partial panel replacements can be successful employed.

The best approach in a major repair is to replace the panel along the factory seams. If possible, the factory bonding strips should be retained and remain in place to provide a guide for the placement of the panel. The old panel is simply cut off short of the flanges and then the bonding areas are ground back to remove the original panel adhesive, and the new panel is bonded in place. The key here is to carefully fit-up the panel prior to bonding until it shows perfect alignment when screwed and clamped in place. Grind, trim, and adjust until the panel falls into place perfectly before reaching for the panel adhesive. Once everything is confirmed to be perfect, the panel is bonded in place using a specialty Corvette body panel adhesive, or a panel adhesive rated by the manufacturer for use with fiberglass. When the panel is clamped and screwed into position, spread and feather the excess bonding adhesive using a putty knife or plastic spreader where it squeezes out to the outer surface. After the adhesive is cured, remove the clamps and screws and apply a layer of panel adhesive over the length of the bond line to act as a filler, and then fill and finish with conventional filler as required.

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Primer and Blocking
Difficulty: 3 Wrenches

Once all of the body repairs have been made, getting a Corvette's body ready for paint requires the tedious process of using a primer surfacer and "blocking" the car smooth. The primer acts as a filler material, helping to level the surface and filling small imperfections. Primer surfacers come in a wide range of formulations, depending upon the brand or product line, including urethanes, epoxies, and polyester resin based products. All of these utilize an activating catalyst which creates a more stable cured product in comparison to older air-dry lacquer-based primer surfacers. Again, we'll issue the warning to make sure that the primer product being considered is rated for fiberglass use, and advise that the primer should be a part of the product line system from the manufacturer of the intended finish top-coats.

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The idea in using a primer surface is to build a layer of primer as filler material on the surface of the body, and then sand the surface back in a way that allows the primer to remain in the lower areas, bringing the entire body up to an even, smooth, and level surface. This is done by "blocking" or block-sanding the body by hand. Block-sanding simply means sanding the surface with the paper backed-up by a backing pad or sanding board, and using a technique to enhance the leveling action. There is real skill involved here, and the choice of backing blocks depends upon preference. Some can work the curved body of a Corvette to perfection using a hard, rigid sanding board, while others prefer a flexible sanding block. Generally, blocking is done using long strokes following the lines of the body panels, and the "breaks" of the panel's curvature. A criss-crossing motion is often used in multiple passes.

An aid to successful blocking is using a primer guide coat. Here, a contrasting color of primer or basecoat is lightly dusted or fogged over the primer before sanding. The guide coat will provide a visual reference to the sanding progress, since it will be sanded off the high spots, and remain in low areas or those that need further sanding. The guide coat will help identify areas that might require further filling, since those areas will not "clean" with sanding even though the adjacent areas have been virtually sanded through the primer layer.

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The blocking process will usually require more than one go around, and may actually end up taking several, meaning that the car will need to be blocked, and then re-primed, and sanded again, until the surface will block-sand to perfection. Often a painter will prefer to use a coarser sandpaper for the first go-around with block-sanding, such as 180-220 grit, to aggressively cut the primer level, with finer paper such as 400-600 grit used in the later block sanding go-around (or whatever grit is recommended as the final surface for the paint being used). This is definitely a time consuming and tedious process, but it makes all of the difference in the final outcome of a paint project.

Difficulty: 4 Wrenches

After the intensive effort in bodywork, prep, and block-sanding, the final painting is just the icing on the cake. The work in the paint booth will vary, depending upon the materials being used and the type of paint. A basic single stage paint job will just require two to three coats of color to be sprayed, and it's all over. An involved custom candy or pearl effect paint might take eight hours of spray gun time in the booth. The key to success is to become familiar with the material being used. The manufacturer will have the product data, which will include the recommended application technique, and recommended spray gun specifications and air pressure.

Often the painting stage does not start with paint at all, but a sealer coat of primer. This will depend on the specific requirements of the top-coat materials, and even the primer used at the surfacing stage. The sealer coat may also be tinted to resemble the final top coat color, which will help in achieving an even coloration in the final finish. Follow the system for material sequence as specified by the manufacturer. Generally, the paint must be applied in sufficient thickness to provide a uniform coverage and color, while clear must have sufficient film thickness for the cutting and polishing process. The most important thing in paint application is to apply each layer of material as smoothly, and with as little surface texture, as possible. This will come down to many factors including the paint mixture and reduction, air pressure, the quality of the spray equipment, and the painter's technique.

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When applying the paint, cleanliness is vital. Dirt and contaminants will ruin a perfectly prepared surface, so it's imperative that the vehicle's surface, the environment, paint materials, and air supply are clean. If a major problem is encountered when attempting to paint, the best course of action is to stop, fix the problem, and then come back to attempt the job later. Even if cutting and polishing after paint is the plan, it will only go so far in correcting flaws in the paint application.

Difficulty: 3 Wrenches

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If everything goes right, the moment of rolling a freshly painted Corvette out of the paint booth is one of the most satisfying you'll experience as an enthusiast. While modern catalyzed paints will cure in a matter of hours, it will actually take a period of weeks for the paint to reach full hardness. Generally, most paints can be cut and polished shortly after painting (check the specific recommendations for the materials used), and after the paintwork is done comes re-assembly. The amount of work here can be anything from attaching a few articles of trim, to fully building up your Vette from a bare body, depending upon the starting point. With the look of gleaming fresh paint, you'll find it hard to attach anything to the body that is not as perfect as the new finish

Getting the car to this stage requires considerable work, and one of the chief concerns during re-assembly is to protect that investment and avoid damaging the new paint. When re-assembling bolt-on body panels, adjusting doors, and aligning the hood, the new paint can easily be gouged or scraped. Some extra hands on deck to handle the heavy items and the use of foam pads and lightly low-adhesive masking tape on panel edges will minimize the potential for damage.

Another Approach
While most of the information presented here involves intensive paint projects, starting from the bare fiberglass and working up, not all Corvette repaints necessarily require starting from the ground up. Many cars, particularly late-model machines still in their factory finish, can be given a good cosmetic paintjob with a more basic approach. The C4 pictured here was in very sound condition, wearing its factory paint. The sensible approach for this driver was to simply repaint the car.

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In this case, the disassembly was kept to a minimum, with some trim removal and a detailed masking. The factory paint was in very sound condition, so it was simply wet-sanded to scuff the surface for adhesion of the repaint materials. The entire body was hand-sanded, which avoided the potential for damage to the panels, as well as any remaining trim, or glass, which can easily be scratched while machine sanding. The body was thoroughly inspected, just as in a complete body restoration, and a few minor surface flaws were located. These flaws were spot-repaired, with fiberglass mat used in the few minor cracks found. Once reinforced with 'glass, the areas were blended with filler, spot-primed, and sanded. The entire body was then given a surfacer coat, guide coated, and block-sanded once. Extensive blocking was not required, since the panels were generally in very good condition. From the block-sanding, the car was moved into the booth, masked, and then shot with sealer, base, and clear. After buffing, the car presented a finish the owner could be proud of.


J & D Corvette
Bellflower, CA 90706



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