Exploring and Comparing Factory-applied and Field-applied Coatings

Full disclosure: My involvement in the coatings industry centers around the field of prepainted metals. These factory-applied coatings were always fascinating to me because metal coils of all types of substrate pedigrees could be unwound onto a paint line and all the processes needed for painting completed in a matter of minutes. These processes went all the way from cleaning the surface to curing the paint, resulting in pristine coils waiting to be formed into parts for almost every market. Therefore, for purposes of this article, “factory applied” is defined as painted before forming, or prepainted. Conversely, “field-applied” refers to painting after forming—regardless of the application method or painting location. Factory-applied painting was very different from what some call “the traditional” method of applying coatings, which involves forming the parts, putting them together, and then cleaning and painting the end product. This method of painting after parts are formed could be done in an immersion or spray painting section of a facility, outsourced to another company, or painted on location during construction. Joseph L. Hunter, an early pioneer in the paint and coatings industry, invented the first coil coating apparatus to streamline the very time-consuming chore of painting venetian blind slats in 1930. This coating method was quickly adopted by the venetian blind industry. In the 1950s, coil coating lines were designed to handle large steel and aluminum coils and the industry grew by leaps and bounds.