AIC's 45th Annual Meeting

Butvar® is the trademarked name for a series of polyvinyl butyral (PVB) resins used in a wide variety of industrial applications, most notably in laminated safety glass. Commercially, PVB resins are used as adhesives, coatings, and binders and are valued for their optical clarity, adhesion to varied surfaces, rheology, toughness, and flexibility. In conservation, Butvars® have been used primarily for the consolidation of deteriorated wood, but also for consolidation of stone, plaster, bone, fossils, and baskets. This paper will review the properties of Butvars® and their conservation applications and will present two treatments of paintings in the collection of the Saint Louis Art Museum in which Butvar® B-98 was used to consolidate friable matte paint. The first case study, Enforcer, 1962, by Larry Poons, was created with Liquitex acrylic paint and Fabspray, a proprietary fabric paint with vinyl and alkyd resin binders marketed for spray-painting upholstery. While the acrylic paint was in excellent condition, the Fabspray was matte, highly deteriorated, and powdering off the surface of the canvas support. Several consolidants were evaluated, including Butvars® of varying molecular weight, gelatin, and methylcellulose. Butvar® B-98 performed best and was sprayed in several applications to consolidate the friable paint layer with minimal change to the surface sheen and gloss. The second case study, Micenic, c. 1942, by Siegfried Reinhardt, is a small oil painting on pressed board. The paint layer had poor cohesive strength and was lifting from the underlying ground in local areas. Typical consolidation approaches were unsuccessful due to the friability of the paint, which crumbled under any pressure or contact. Butvar® B-98 was applied to improve cohesion of the paint film and was followed by dilute BEVA® 371 to set lifted paint flakes back in place. Application techniques and solvents were selected to ensure that the BEVA® did not undermine the Butvar®, and the two-step consolidation proved successful both structurally and aesthetically.