Abstract:
Synthetic ultramarine inorganic blue pigment is one of common type of blue pigment
which can be easily produced from locally available geomaterials. The chemical
composition of these geo-materials (sulphur and clay) was investigated by the silicate
analysis method and Synthetic ultramarine blue pigment was synthesized by a solid state calcination process. A literature review was used to select and investigate the
effect of reaction temperature (750, 800 and 850 0C), residence time (4, 5, and 6
hours), and sulfur weight amount (20.56, 21.34 and 22,06w %) on the blue pigment
production process. The main blue coloring strength was identified by Commission
Internationale de l'éclairage laboratory coordinate value (L*, a*, b*) where L* is the
lightness value starting from 0 up to 100, a* and b* are correlation coordinates which
show the coloring value between +60 and-60. The optimum process parameters for
the production of blue color pigment were determined by a design expert. The optimal
process parameters were a reaction time of 4.87hr. (4 hours and 52 minutes), reaction
temperature (799.840C), sulfur concentration (22.06 wt. %), and blue color value
(b*=-13.13). The pigment properties were characterized by density, moisture content
and color value, resistance to heat, detergent, acid, alkali and light. The crystalline
nature structure and the functional group were determined by X-ray diffraction and
infrared spectroscope. The quality of the blue color strength was also examined by
spectrophotometer CM- 600d. According to the results of the research, there's an
opportunity to produced ultramarine pigment material by using local geo-minerals.
