Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by function]

Anotations

Scope note:

Any materials added to increase optical density and make opaque. In ceramics, opacifiers are substances added to glaze or enamels for this purpose. They include tin oxide, titanium dioxide, and lead chromate.