Pencils are special pens for writing and drawing and sketching. It has a history of more than four hundred years. Among them, there are many types of pencils for drawing and sketching. They are divided into three stages of development, namely graphite and wood. Penholder, pencil with cap; in addition, its color has stripes such as red and white, black and white, yellow and black.
The hardness mark of pencil lead core generally uses “H” to indicate a hard pencil, “B” to indicate a soft pencil, “HB” to indicate a pencil with moderate hardness, and “F” to indicate a pencil with a hardness between HB and H. Arrangement (from soft to hard) 9B, 8B, 7B, 6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, 9H, 10H, etc. Hardness level. The larger the number in front of H, the harder the lead and the lighter the color. The larger the number in front of B, the softer the lead and the darker the color. The classification of pencil shafts is based on the amount of graphite in the pen core.