Polishing pitches are deposited by casting, dropping or melting them on polishing tools, either pure or mixed with enhancing materials (sawdust, felt flakes). Hard types of polishing pitches and those containing enhancing materials are suitable for pre-polishing and, when using higher pressure and speed, while soft types are used for smoother application techniques in precision optic industry.
|Other Hardesnesses||17,18,19, 20, 21, 22||24, 25, 26, 27, 28, 29, 30, 31||33, 34, 35, 36, 37, 38, 39, 40, 41|
Hardness is defined according to the original Zeiss
Jena standards as the temperature which makes a needle with a pinpoint of 1 mm2 penetrate 2 mm deep into the material within 10 sec at a pressure of 1 kg.