The coating of plastics has occupied the attention of polymer chemists for the past 30 years. Several problems are immediately obvious. If the coating is a hard resistant thermoset like a baked phenolic, it provides a surface to which every few substances will adhere: Two generations ago all telephones were black for this reason. If on the other hand the polymer is thermoplastic, adhesion is not necessarily a problem but solvents are, since the solvent in the coating can erode the polymer's surface. Plastic surfaces require coating for a number of reasons and this has caused imaginative chemists to devise new coatings and new coating techniques to meet the challenges. Some plastics require coatings simply for decoration. Some require coatings in order to protect the surfaces. This is particularly true in the electronics area. The need for coatings for plastics has been accelerated by the desire of the automotive industry to replace metal with polymers. If the plastic is part of the automobile body it must be coated to match perfectly the coated metal part. Reaction injection moulding (RIM) is providing a means for supplying the automotive industry with large parts such as bumpers, fascias, and in the not too far future doors and hoods. Naturally the coatings on these must duplicate precisely the coating on the metal portions of the car.