PA types 6, 66, 610, and 612 are different variations of the polyamide molecule. The different nylon manufacturing processes and ingredients are different, and this can affect the resulting filament performance in brushes. PA 6, for example,contains the ingredient caprolactam, which is frequently notcompletely bonded to the molecule. PA 6 brush filaments in an aggressive brush tool can leave a residue on the part.
PA 610 is made from extracts of the castor bean plant.
The base sebacic acid will contain some impurities and can vary in quality.
Nylon 66 and 612 are synthesized polymers made from 100% petrochemical derivatives, so the quality is carefully controlled to ensure consistent quality.