Conventional surface coatings or paints applied in spray painting are usually a mixture of: • resins or polymers which ‘cure’ or ‘harden’ to produce a durable coating on the application surface • coloured pigments and fillers, and • solvents or water acting as carriers for the resins that evaporate during application and drying. Solvent-based coatings were the first to be developed and are generally the preferred type for smash repairs. Water-borne coatings also contain small amounts of solvents. Water-borne coatings are used by vehicle manufacturers for undercoats and primers, but are mostly unsuitable for refinishing because of relatively long drying times. Top coats or finish coats have tended to be solvent-based for automobile coatings.