Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by property]
6. surface active agent

Anotations

Scope note:

Liquid or chemical added to a solution to reduce the surface tension and give greater ease of mixing and stability, such as liquid added to watercolor so that the paint will flow freely and take evenly on the paper.