Hierarchy classification:

1. top of the aat hierarchies
2. Activities Facet
3. Processes and Techniques (hierarchy name)
4. [processes and techniques by specific type]
5. [subtractive processes and techniques]
6. cleaning
7. purification (cleaning process)

Additional parents:

1. top of the aat hierarchies
2. Activities Facet
3. Processes and Techniques
4. processes and techniques by specific type
5. temperature-related techniques

Anotations

Scope note:

The act of purification, clarification, or distillation of a substance or product, by a series of industrial processes. Examples may include the processing of sugar, crude oil, or metals.