For a good finish, it is essential to prepare the surface well, sanding to provide a key and thoroughly degreasing with naphtha (panel wipe). Areas not to be painted should be masked, although for repair work it is important to avoid spraying a full coat right up to the masking tape, which will leave a hard line; it is better to fade the new paint into the existing paint, especially if the color is difficult to match. The flow of paint should be started or stopped on the masked area rather than over the area intended to be painted, as aerosols often discharge "blobs" of paint under these conditions. Coats should be built up lightly enough to avoid runs, but a "dry" finish must be avoided by spraying too thinly or from too far away. The optimum distance between the can and workpiece is around one foot (30cm). Most automotive paints will require a clear lacquer after the color coat, normally 24 hours later. The color coat should be well matted down with very fine abrasive paper before applying the lacquer.