The meaning of the pencil model: the hardness mark of the pencil lead, generally use "H" for hard pencils, "B" for soft pencils, and "HB" for moderately soft and hard pencils.

Arrangement (from soft to hard) 12B, 11B, 10B, 9B, 8B, 7B, 6B, 5B, 4B, 3B, 2B, B, HB, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, 9H, 10H and other hardness grades.

The larger the number in front of H, the harder the refill and the lighter the color. The larger the number in front of B, the thicker the color and the softer the refill. The classification of pencil shafts is based on the amount of graphite in the refill. Among them, H-type pencils have relatively high refill hardness and are suitable for objects with relatively hard or clear interfaces, such as woodworking scribing, field drawing, etc.; HB-type pencils have moderate refill hardness and are suitable for general writing, or typing For contouring, type B pencils, with relatively soft refills, suitable for drawing.

When soft lead is used as a large tone, it can easily and quickly open up the relationship between light and shade and create a tone atmosphere of the picture. It is suitable for depicting dark and dark parts, but due to its poor adhesion of pen dust, it is easy to stain the picture. Hard lead can play a role that soft lead cannot match in dealing with the texture of the picture, delineating the lines with rich changes, and realizing the subtle changes of the bright surface.

When using, usually use the soft lead to "prime" the dark color, and use the hard lead to describe in depth, following the order of soft first and then hard. If the order is reversed, the soft lead will not be able to draw deeply in the place where the hard lead has been painted many times.