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.
| CSA Group | |
|---|---|
| Product Category | Standards and Technical Documents |
| Product Number | ISO 9177-2:1989 |
| Product Name | Mechanical pencils - Part 2: Black leads - Classification and dimensions |
