Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by function]
6. colorant (material)
7. pigments
8. [pigment by color]
9. blue pigment
10. synthetic inorganic blue pigment

Anotations

Scope note:

A coarsely ground blue potassium glass containing small amounts of cobalt oxide, which provides the source of the blue color. It is used as a blue colorant in paints, glazes, glass, bluing paper, laundry blue, starch, textiles, and rubber. Although it was intended as a substitute in painting for natural ultramarine blue, which was very expensive, it was discovered that smalt blue discolors when placed in an oil-based medium.