In a shop context this covers the final finishing after paint work and the polishing of fabricated metal parts.
Compounding removes oxidation, scratches and sanding marks. Compounds are graded by cut — heavy cut for severe defects, medium for general correction, fine for finishing. The pad, the speed and the pressure all affect how much cut is applied, which is why the same compound can produce very different results.
Polishing refines the surface after compounding. Polishes have finer abrasives and produce gloss rather than removal. Multiple stages with progressively finer polish and softer pads are what produce a scratch-free finish; skipping a stage leaves haze that shows up in direct light.
Protection — wax, sealant and ceramic coating — extends the life of the finish. Wax gives depth but limited durability; synthetic sealants last longer; ceramic coatings last longest and give the most chemical resistance, but require proper surface preparation to bond.
Metal polishing for bare aluminium, stainless and chrome uses different compounds and wheels. The compound must match the metal — a compound for steel will not produce a mirror on aluminium, and using too aggressive a compound on thin plating cuts through it.
