Almost every syllabus, teacher, and standardized test requires a No. 2 pencil. Are there other ... added to a mixture determines the hardness of the lead. Although the method may have been agreed ...

Q Were pencils ever really made with lead, or has it been graphite all along ... The number printed on the side of a pencil indicates hardness of the graphite. The higher the number, the harder ...

You can even use one yourself to figure out the hardness of any given material. The hardest pencil, rated 10H, corresponds to roughly 3 on the Mohs scale. For reference, a human fingernail ...