Per I-CAR curriculum: “Overspray is a common defect on a refinished vehicle. One of the most effective methods of removing overspray is the use of a clay bar. Several defects can be removed using clay. Clay is a nonaggressive material that:

• is specially formulated for defect removal. Modeling clay is NOT a substitute.
• works on any hard surface. Clay will not work on soft, porous trim or moldings, especially if contaminants have penetrated the surface.
• is effective for removing overspray because the overspray is on a surface that is not prepared for it. There is no chemical or mechanical bond, so the material sticks to the clay when it is rubbed across the surface.
• can reach where buffing or sanding may not, or where solvents may be damaging.

Besides clay, other methods for removing overspray include:

• scraping on glass with a plastic razor blade. Metal razor blades can easily scratch glass.
• applying a solvent from a spray bottle and wiping off the overspray.
• using a sponge pad and an adhesive cleaner on fresh overspray, or a mild buffing compound on dried overspray.
• sanding, followed by buffing. This is performed in extreme cases.

Do not use steel wool, which is too aggressive, and also leaves metal fibers in crevices that will corrode.”