In 1564, a catastrophic hurricane hit the island of England, and many large trees in the severely affected Cumberland area were uprooted. After the storm, a black mineral was found under the roots of the trees. As long as you lightly scratch the object, you can leave a black mark, which is "graphite". Local shepherds often use it to mark their sheep for easy identification. Later, someone made it into a stick shape and sold it to merchants for marking packaging. In 1781, after many experiments, the German chemist Faber mixed graphite powder with sulfur, antimony, and rosin to make a paste and then squeezed it into a bar shape. This was the prototype of the pencil. This kind of pencil has a certain hardness and is much easier to write with than 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 simply took the Barrodale Graphite Mine into the royal family and designated it as a royal exclusive product. However, writing with graphite strips can easily stain your hands and break easily.
The task of putting the wooden shaft jacket on the pencil was completed by the American craftsman Monroe. He first built a machine that could cut out wooden strips, then carved thin grooves on the wooden strips, put the pencil lead into the slot, then aligned and glued the two wooden strips, and the pencil lead was tightly The ground was embedded in the middle, which developed into the pencil we use today.
New members
With the development of the times and the advancement of technology, a lot of technological content has been injected into the manufacturing of pencils. There are retractable mechanical pencils with protective cores, mechanical pencils without residual cores, paper pencils, etc.
The biggest feature of the core-protected retractable mechanical pencil is that its lead core protective tube can retract under a certain pressure. This kind of pen uses a metal chuck, which is equipped with a protective spring to prevent heavy pressure. After pressing, it can semi-automatically remove the core. Not only does the core come out accurately, but it can also avoid puncturing the pocket and protect the lead; the mechanical pencil without residual core is different from the ordinary mechanical pencil. Unlike mechanical pencils whose lead can only be used up to 12.4 mm, non-remnant mechanical pencils can still be used even if the lead is used down to the last 1 mm. This is a major innovation in the mechanical pencil in more than 100 years. It mainly uses a double chuck 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 pencils are also known as environmentally friendly pencils. It mainly uses waste paper as raw material (replacing wood in traditional pencil production), and is made by simple cutting and fine processing. Compared with traditional wooden pencils, paper pencils use paper instead of wood and are of better quality. The products come in a variety of colors, are easy to curl and have good performance, and absolutely avoid core breakage and chipping in the shaft that are common with wooden pencils. Disadvantages such as folded core and eccentric core are difficult to overcome.
Symbols
Today we see H, B, and HB marked on pencils, which represent the softness and hardness of the pencil. This also has its origin.
Until the end of the 18th century, only Britain and Germany had pencil supplies in the world. After Napoleon launched a war against neighboring countries, Britain and Germany cut off the supply of pencils to France. Therefore, Napoleon ordered The French chemist Comte found graphite ore in his own country and then made a pencil. However, the quality of graphite ore in France was poor and the reserves were small. Comte mixed clay into the graphite and roasted it in a kiln to make the most durable pencil lead in the world at that time. Different proportions of clay mixed into graphite produce pencil leads with different hardnesses and different color depths. "H" is the initial letter of "Hard" in English, which stands for clay and is used to indicate the hardness of the pencil lead. The larger the number in front of "H" (such as 6H), the harder the pencil lead is, that is, the greater the proportion of clay mixed with graphite in the pencil lead, the less obvious the written words are, and it is often used for copying. "B" is the initial letter of "Black" in English, which stands for graphite and is used to indicate the softness of the pencil lead and the obviousness of writing. "6B" is the softest and has the darkest writing, and is often used for painting. Ordinary pencils are generally marked "HB", and pencils used to mark answer sheets during exams are generally marked "2B".
Special functions
Many people may not know that pencils can also identify the authenticity of diamonds.
After the diamond is moistened with water, scratch it with a pencil. The surface of a real diamond will not leave traces of pencil scratches. Fake diamonds made of crystal, glass, tourmaline, etc. will leave traces