Laure Albin Guillot (1879-1962) Marguerites, c. 1927. Vintage pigment print on gold ground, signed lower right. 29 x 38 cm In May 1927, Laure Albin Guillot filed a patent with the French Ministry of Commerce and Industry, entitled "Perfectionnements aux reproductions photographiques" ("Improvements to photographic reproductions"). The patent describes a process combining a pigmented potassium dichromate emulsion and a support (known as the substratum) made of precious metal leaf, wood or mother-of-pearl.)