What happens if I drop my clay bar on the floor?

Discard it immediately. A clay bar that touches the ground picks up grit that embeds into the clay surface, and that grit will scratch the clear coat on the next pass. There is no way to clean it out. The same rule applies to synthetic clay mitts and towels, though a mitt can be rinsed under running water to release surface contamination before being reused.

Which clay grade should I choose, and does temperature matter?

Choose a softer grade (soft or medium) for cold weather, when firm clay becomes too stiff to glide cleanly and increases marring risk. Use regular (firmer) grades in warmer conditions when the clay stays pliable. On a cold day, always warm the clay in your hands before starting. Bilt Hamber white clay (soft grade) is a suitable default for most paintwork and glass in typical UK conditions.

How do clay bars compare to synthetic clay mitts and towels for marring?

A soft clay bar leaves minimal marring on medium-hardness paint when used with a proper lubricant such as ONR at 1:64 dilution. Synthetic formats (mitts, towels, clay blocks) showed visible marring under an inspection light in a comparative test on the same panel. Synthetic mitts are faster on large flat panels and rinse out easily, but clay bars outperform on heavily contaminated paint where synthetics tend to skate over deeply embedded particles.

Can I clay matte, satin, or vinyl finishes?

No. Clay is safe on smooth surfaces including paint, glass, and headlights, but it is too abrasive for matte or satin finishes and for vinyl. Using clay on these surfaces will alter the texture and sheen permanently. If a matte or vinyl panel has contamination, use chemical decontamination only and consult a detailer before applying any mechanical decon method.