HB: hard black;

2B: 2 black;

4B: 4 black;

The number represents the degree, the larger the number It means that the darker it is, the higher the carbon content, and the softer the signature;

Similarly: 2H, 4H, the larger the number, the higher the hardness.

H represents a hard pencil, the larger the number in front, the harder it is:

B represents a soft pencil, the larger the number in front, the softer the lead;

< p>HB means a pencil with moderate hardness and softness, suitable for daily writing.

B stands for Black, which means black. It represents the depth of black drawn by a pencil, which is the degree of visibility, so there are 2B, 3B, 4B, 6B, etc. 6B is the blackest and softest when written;

H stands for Hard, which means the hardness of pencil drawing. It is divided into different grades: H, 2H, 4H, 6H, etc. 6H is the hardest, and it is not very obvious. HB is commonly used. label.

Today's pencils are made of graphite and clay and do not contain lead. They are so named because of their historical evolution.

In ancient Greece and Rome, lead rods similar to pencils were made from metallic lead. They are mostly cone-shaped, leaving traces of lead after rubbing with other objects, and are used to draw lines and make marks. In the 14th century, pencils similar to today's appeared in Europe. In 1565, the British began to hand-make the most primitive wooden pencils using graphite as the refill. In 1662, Germany built the world's first pencil factory. From 1790 to 1793, France's Kant used clay to bond graphite to make a pen core, laying the foundation for the modern pencil industry.