The working principle is to use rubber molecules and other material molecules between the easy to force, and the rubber itself is soft texture, do not destroy the paper. In daily life, even if the same words are written, we can tell which one is written by pencil and which is written with a pen.
and words written in pencil and words written with pens must be taken with different erasers to wipe them off. Write with a pencil, the handwriting is only kept on the surface of the paper, not deep into the inside of the paper, but the pen is different. When writing with a pen, the handwriting is immersed in the inside of the paper and dyed the paper into a ink color.