They come in a variety of grades: B pencils have more graphite in them ... you can purchase the 9000 pencil in any hardness individually. The casual sketcher perhaps doesn’t need the extended ...

That number two rating is based on a scale for hardness: 1 ... David Thoreau when he was working at his family's pencil factory. American graphite was inferior to English graphite, and to separate ...

Numbers are used to classify grades of pencils in the United States ... A No. 2 pencil is towards the middle when it comes to the hardness of lead (graphite) and the darkness of the shade.

Before Conté, pencil hardness varied from location to location ... using a combination of numbers and letters known as the HB Graphite Scale. So why are testing centers such sticklers about ...

and HB-grade pencils fit the bill. But what do those grades mean? The letter H in the grading system designates the graphite’s hardness, the B its blackness. The degree of each attribute is ...

The pencils are graded by their ratio of graphite to clay. Grades ranged from 9B to 2H, where H denotes the hardness caused by the pencil’s clay content, and B denotes the blackness due to the ...

Unlike diamond, graphite can be used as a lubricant or in pencils because the layers cleave readily. It is soft and slippery, and its hardness is less than one on the Mohs scale. Graphite also has ...