BLU OLTREMARE ARTIFICIALE
PB 29/77007 Ultramarine Blue; Ultramarine Blue can be either the pigment extracted from Lapis Lazuli or the synthetic form polysulfide of sodium, potassium, lithium or silver alumino-silicate. Synthetic ultramarine is made by mixing anhydrous sodium sulfate or sodium carbonate with charcoal, clay, rosin, silica, sulfur, and slowly calcined in a reducing atmosphere to 1,380º F (750º C). The various shades of blues, greens, reds and violets are produced by varying heating times and temperatures, mixture proportions, and/or other modifiers. For example Ultramarine Green is the "first product of ignition in the manufacture of Ultramarine blue by the indirect process. Synthetic ultramarine blue has particles that rounder, finer and more even in size than the natural ultramarine. "Since 1828 it is created by fusing together a mixture of kaolin, soda ash, Glauber's salt, sulfur, carbon and kieselguhr. The mixture being fused by heating without air for 7-10 hrs. The resulting Ultramarine Green (PG24) is cooled, then ground and mixed with 7-10% of sulfur, the blue hue develops after heating the mixture for about an hour. The resulting blue colored mass is cooled and washed, then wet ground, levigated and finally ground to a fine powder."
CAS 1317-97-1; CAS 57455-37-5
PB 29/77007 CAS 1317-97-1; CAS 57455-37-5.
Alluminosilicato di sodio polisolforato artificiale. Adatto e stabile in tutte le tecniche. Variante con buona stabilità anche in ambiente acido.