The Roosterman Coat of Arms

Detail of coat of arms	When purchased by the CMA in 1999, this portrait had a coat of arms identifying the sitter as 17th-century Haarlem merchant Tielemann Roosterman. Scholars were able to identify the coat of arms and crest based on a detailed description written in the 19th century.
Tielemann Roosterman was a rich merchant of fine linens and silk fabrics in the city of Haarlem. As the leading portraitist of Haarlem, Frans Hals would have been the clear choice to paint Roosterman's portrait.
Detail of pigments under the microscope	Hals did not paint the coat of arms and crest, which do not date from the 17th century. The proof is in the pigments used in the coat of arms, especially Prussian blue, a synthetic pigment not invented until 1704 and not widely used until after about 1720. This pigment was easily identified in slide-mounted samples studied using a polarized light microscope .
Detail of cross section	Indeed, a microscopic-sized paint layer sample taken from the painting, mounted in resin, and then smoothly polished in cross section, was viewed to determine the exact sequence of layers. Beneath the Prussian blue pigment-containing paint layer, a thin but distinct layer of varnish clearly indicated that the coat of arms was added later over a surface of dried and varnished paint.
The coat of arms was already present by 1866, which is both the earliest traceable date of the painting's whereabouts and the year it was acquired by Friedrich Jacob Gsell (Gsell sold the painting in 1872 to Baron Anselm von Rothschild, the father of Alphonse von Rothschild). Thus, the coat of arms must have been added to the painting sometime between 1704 and 1866. Based on the brushstroke style, experts have narrowed the dates to the period between 1750 and 1800.

Page 2 of 3 | On the next page: Covering the Roosterman Coat of Arms