Due to my experience manufacturing plastics, I receive many calls and requests about how to care for your C4 Corvette Acrylic Targa Top. Basic roof maintenance goes a long way toward increasing the life and appearance of acrylic panel.
For a bit of history, when Chevrolet redesigned the Corvette for introduction in 1984, they came up with a lot of great ideas used in other sports cars in the past. Instead of the T-Top roof panels that had been used on the 1968-1983 Corvette C3, they opted for a Targa roof like the Porsche 911. The standard roof was a fiberglass panel painted the same color as the car. . Chevrolet also had an optional sunroof that featured a bronze or blue smoked plastic. Lexan was originally used on roofing in 1984 but was found to be easily scratched. Lexan is a very tear resistant material, but the downside to its tear strength is its soft surface that scratches quite easily. As a side note, all race cars use Lexan for their front windshields from local tracks to the Nascar Nextel Cup Series. In the Nextel Cup and Nationwide Series, race teams use tear-off films on top of the Lexan that can be removed during the race, minimizing scratches on the windshield. Later in the 1984 model year, General Motors switched to acrylic with a scratch resistant coating to help prevent scratches on the roof.
Caring for an acrylic ceiling panel is easy. Wash the panel with a mild detergent, Walmart standard car wash detergent is fine. The key is to spray the ceiling well with a hose to remove loose dirt BEFORE CLEANING THE SOAPY RAG. After the ceiling is dry, apply wax to the ceiling. It is important NOT to use a cleaner wax, repeat DO NOT use a cleaner wax as it has abrasives to clean dirt and rust on a car paint and will scratch the plexiglass roof. I suggest applying several coats of wax and applying frequently as the wax will burn in the sun.
Removing deep scratches from the ceiling is a bit trickier, but if you’re careful and cautious, it shouldn’t be a problem. You should first sand down the scratch with 1200 grit sandpaper. Personally, I use wet / dry paper and wet sand the scratch with water that has a little dish detergent mixed in with it. The water acts as a lubricant to help keep scratches on the sandpaper surface to a minimum. After this step, pat the area dry and buff. If it is a small scratch, you can rub it by hand. Starting with a heavy-duty cutting compound, buff the area with a soft cloth. Then buff it with a finish cut polishing compound until all scratches are gone and the shine has come off. The last step is to apply a few coats of paste wax to the ceiling. If the scratch is large, you will need to use a buffing wheel. Before using a buffing wheel, make sure you have experience with it. If not, I suggest you call an auto detailer in your area.
For fine scratches on the surface, it is not necessary to use sandpaper, simply sand the ceiling by hand with a scratch remover compound, such as Maguire’s. It may take some time, so be patient.