How do pencils keep improving?

1564, a disastrous hurricane hit the island of England, and many trees in the severely affected Cumberland area were uprooted. After the storm, people found a black mineral under the roots of trees. As long as you make a slight stroke on an object, you can leave a black mark. This is graphite. Local shepherds often use it to mark sheep for easy identification. Later, someone made it into a stick and sold it to a businessman as a packaging mark. 178 1 year, German chemist Faber mixed graphite powder with sulfur, antimony and rosin, made it into paste and extruded it into strips, which was the prototype of the pencil. This kind of pencil has a certain hardness, which is much easier than writing with a graphite rod. Inspired by this, people cut graphite blocks into small strips for writing and painting. This is the earliest pencil. Soon, King George II of England simply owned the Barodale graphite mine and made it a specialty of the royal family. But writing with graphite strips is easy to get dirty and easy to break.

The task of putting a wooden stick coat on a pencil was completed by American craftsman Monroe. He first built a machine that can cut wood strips, then carved a groove on the wood strips, put pencil lead in the groove, and then aligned and glued the two wood strips, with pencil lead tightly embedded in the middle, which developed into the pencil we use today.

new hand

With the development of the times and the progress of science and technology, the manufacture of pencils has also injected a lot of scientific and technological content. Telescopic mechanical pencil with core protection, mechanical pencil without residual core, pen and paper, etc.

The biggest feature of retractable movable pencil with core protection is that its lead core protection tube can be retractable under certain pressure. This pen uses a metal chuck, which is equipped with a protective spring to prevent heavy pressure. After pressing, it can semi-automatically eject the core, which not only can accurately eject the core, but also can avoid puncturing the pocket and protect the lead core. Mechanical pencil without residual core is different from mechanical pencil, where the lead can only be used to 12.4 mm, and mechanical pencil without residual core can still be used even if the lead is used to the last 1 mm ... This is a great innovation of mechanical pencil in the past 100 years. It mainly adopts a double-clip structure in the pen. The front chuck clamps the front end of the lead, and the rear chuck is responsible for clamping and pushing the lead. Paper and pencil, also known as environmental protection pencil. Mainly using waste paper as raw material (instead of wood in traditional pencil production), it is made by simple cutting and fine processing. Compared with traditional wood-based pencils, paper-based pencils have better quality, diverse products, easy rolling and good performance, and absolutely avoid the shortcomings of broken core, broken core and eccentricity that wood-based pencils can't overcome.

sign

Today, we see that H, B and HB marked on the pencil represent the hardness of the pencil, which is also historical.

Until the end of 18, only Britain and Germany had pencils in supply. Britain and Germany cut off the supply of pencils to France after Napoleon launched a war against neighboring countries. Therefore, Napoleon ordered the French chemist Comte to look for graphite ore in his own country and then make pencils. However, the quality of French graphite ore is poor and its reserves are small. Comte mixed clay with graphite and put it in a kiln for barbecue to make the most durable pencil lead in the world at that time. Pencil lead produced by different clay proportions in graphite has different hardness and color. "H" is the initials of the English word "Hard", which stands for clay and the hardness of pencil lead. The larger the number before "h" (such as 6H), the harder the pencil lead, that is, the greater the proportion of clay mixed with graphite in the refill, the less obvious the written words, which is often used for copying. "B" is the initials of the English word "Black", which stands for graphite and is used to indicate the softness of pencil lead and the obvious degree of writing. With "6B" as the softest and blackest handwriting, it is often used in painting. The label of ordinary pencils is generally "HB", and the label of pencils used to paint answer sheets in exams is generally "2B".

Specific function

Many people may not know that pencils can also identify the authenticity of diamonds. After the diamond is wet with water, scrape it with a pencil, and the surface of the real diamond will not leave pencil marks. Fake diamonds made of crystal, glass and tourmaline will leave traces.