ISO 9177-2:1989, Mechanical pencils -- Part 2: Black leads -- Classification and dimensions
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Book Details
Description
Two types are available, black leads in which the binding agent is an organic polymer (designated by the letter "P"), and black leads in which the binding agent is clay (designated by the letter "C"). Classification is made according to the degree of hardness. Part 1 deals with the classification, dimensions, performance requirements and testing.
