In the 1960s a coating system formed by overcoating a molten hot-melt coating with a latex paint was conceived as an answer to a search by the wood siding industry for a primer to improve paint performance on its product. Performance testing, including weather exposure, had a positive outcome, but circumstances prevented commercialization. Thirty years later, the originator of the concept undertook a more thorough investigation. This article is a public a report on coating system composition and performance.

The concept of an organic coating system consisting of a hot-melt coating (also known as thermoplastic coating), overcoated with a water-thinned coating while in the molten state, was explored by the development of solvent-free shop primers for forest product-based exterior architectural components. These shop primers with and without commercially available finishes were compared to selected commercial coating systems on various substrates by weather exposure in multiple locations. The concept is in its infancy, but coatings developed are commercially practical with performance equal or superior to conventional coating systems of recognized quality. Suggested applications of the concept include road marking and interior trim. The field is open for exploitation.