Fun facts about pitch and the pitfalls of ignorance
Birgit E. Gillman, Flemming Tinker · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1999
The various properties of polishing pitches have different advantages and are selected according to the type of work intended. It is important to check pitch properties before a pitch lap is poured; to ensure that the final polishing lap properties will be as desired. A simple penetrometer test is utilized as a quality control tool for measuring the hardness (viscosity) of various types of pitch as received from the manufacturer. Only a small sample, 20 grams, is needed for this test. Another simple method for determining pitch quality is the measurement of the softening point. A description of this method and typical results will be described. Lastly, the 'tackiness' of pitch and its importance will be discussed.