Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by composition]
6. inorganic material
7. glass (material)
8. [glass by technique]
9. crown glass

Anotations

Scope note:

Refers to a type of glass characterized by central circular ridges around a pontil mark. It is a pane created from the central portion of a sheet of crown glass, which is created by spinning a bubble of glass on a rod and cutting one end so that the bubble opens into a large circular sheet.