State of the Art of Factory Applied Protective and Decorative Plastic Coating Finishes

Abstract

The use of plastic coatings to protect or decorate metallic substrates may be seen by many to be a black art or, more crudely, bucket chemistry. This is far from reality. It is therefore the intention of this paper to dispel any myth relating to plastic finishing and demonstrate that several factors must be considered before the application of a plastic coating can satisfy the engineer's particular need. Whether one is desirous of protection against corrosion, a decorative and aesthetic finish, or a combination of cosmetic and anticorrosion characteristics, the design of the component to be coated, the attention to substrate preparation, and the selection of the coating medium should be the main features considered. Unless agreement between the designers, specifiers, and coating contractors can be reached on these fundamental concepts, the coating may not be able to perform the task required of it. The coating is often the final stage in a long line of activities and, being the first thing the user sees, often attracts unfair criticism when component design or coating type may be the prime cause for concern. By examination of design criteria, service conditions, inspection regime, and the coating materials atthe right time in the project span, it should be possible to produce components that perform as required. One cautionary note should be added, however: coating will not necessarily provide a limitless life to the component, although it will provide longevity compared to a similar but uncoated item.