Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by composition]
6. organic material
7. elastomer
8. [elastomer by form]

Anotations

Scope note:

Light spongy rubber made by mechanically whipping air into the rubber latex prior to curing. It is used for mattresses, cushions, and insulation. Foam rubber turns yellow and becomes powdery when exposed to sunlight.