Elizabeth La Duc and Dr. Aaron Shugar
Abstract
The use of matte paint is often required in conservation for successful inpainting. A matte surface can be achieved in several ways, for example, by using a paint with a high pigment concentration, by abrading the surface to increase roughness, or by adding a matting agent to the paint. While fumed silica is often used as a matting agent by conservators, its efficacy has been called into question. Fumed silica is produced commercially as a thickening or thixotropic agent, not as a matting agent; in contrast, precipitated silica is sold specifically as a matting agent. Paint samples modified with fumed silica (CAB-O-SIL M-5, Cabot Corporation) and precipitated silica (ACEMATT HK 125, Evonik Degussa) were compared with gloss analysis, colorimetry, and differential scanning calorimetry (DSC). In addition, the characteristics of a commercially available matte acrylic emulsion paint were investigated. Precipitated silica was found to be easier to use than fumed silica and nearly as effective at reducing gloss, with a 1% addition to paint reducing gloss by over 60%. Commercially available matte paint was found to be glossier than expected or desired, reinforcing the importance of understanding and testing one’s materials.