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.
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
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.
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.