A review of the development and testing of Incralac lacquer

This paper summarizes the development of commercial Incralac clear lacquer for outdoor copper alloys and reviews the research done in the 1960s with resulting formulations. The introduction of Incralac was groundbreaking for the coating industry and the product has been widely used to the present time. A review of minor formulation changes — mostly to comply with environmental regulations — is presented as well as discussion about how the components affect the overall performance. Originally developed for use on polished copper alloys, the product has been adopted for the protection of outdoor sculpture with varying results over the last few decades. This paper reviews the published performance testing of Incralac in the laboratory and in the field, discusses aging properties and removability, and provides a useful discussion about the challenges in evaluating the product in particular for its application to outdoor sculpture.