This makes it an ideal pencil for technical drawing. As we have already discussed H and B refer to the hardness and blackness of the pencil so what is an F-grade pencil?Īn F-grade pencil is classed as being firm and can be sharpened to a fine point. If you refer back to our diagram of the graphite scale you can see that between the grades of HB and H is the F grade. Or they represent an increase in the hardness of the core due to a higher ratio of clay to graphite producing lighter grey marks ie H, 2H, 3H, 4H, etc. HB is considered to be the middle point of the scale and the numbers represent either an increase in the blackness or softness of the core of the pencil i.e. This equates to the B or Blackness letter on the pencil graphite scale. This equates to the H or hardness letter on the pencil graphite scale.Īnd if you reduce the proportion of clay to graphite in the core of the pencil it is now a lot softer and will leave a darker black mark. If you have a high portion of clay the core of the pencil is very hard and leaves a lighter grey mark on the paper. By altering the ratio of graphite to clay you are changing the properties of the pencil core. The clay is used as a binder to hold the graphite together as it would be too soft to use on its own. Whereas clay is very hard and leaves a light grey mark when rubbed against the paper. Pure graphite is very soft and leaves a dark mark when rubbed against the paper. The core of a wooden pencil is made from two components graphite which is a very soft dark greasy material and clay which is a type of soil made up of several different minerals. For more information check out our guide What is Pencil Lead Made of?Where we go into this in a lot more detail. It was wrongly assumed that it was a type of lead and was centuries later before it was correctly identified as a form of carbon known as graphite. This is not true, and it is historical dating back to the 1500s when graphite was first discovered. First, let us get the elephant out of the room people often refer to pencils as lead pencils which infers that the core of a pencil is made of lead.
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