Pencil is a stationery that we have been in contact with since childhood
As a good partner of the art student, a little helper for answer card
I believe everyone knows the importance of a pencil
But do you know a pencil
It does not contain lead!
Today, I will give you a good popular science
Those things about pencils ~
Past life of pencils
The name of the pencil is not groundless. Because as early as the ancient Roman era, people often used lead rods to marks, and the lead rods were called pencils at that time. However, this real pencil effect is not good, not only light color but also great toxicity.
Until 1564, a shepherd in England discovered a black mineral -graphite (the raw material of the pencil core). This new mineral material has excellent color rendering, so he used it to numbers the shepherd.
Soon after, the merchants found business opportunities and cut graphite into strips for sale, so that people can markers in daily life.
Although people have begun to use graphite to make the prototype of a pencil, everyone does not know that this new mineral is graphite, and because it is the same as lead, it can leave black marks on the paper, which is called “black lead. “”. So the pens made in the early days were called a pencil, and this title continued.
Know the pencil from the standard
Now, the pencil is no longer roughly made into a pen. Instead, it has “put on” a wooden coat for the pencil core through mechanical suppression, forming a pencil we now recognize.
The GB/T26704-2011 “Pencil” stipulates that the pencil is divided into graphite pencils and color pencils according to its lead core materials, and is divided into ordinary and advanced products. Among them, graphite pencils are divided into 6B, 5B, 4B, 3B, 2B, 2B, B, HB, HB, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, 9h in total; Different classifications.
Popular science expansion -HB on a pencil
The pencil we bought daily has HB symbol logos. What does this mean?
When you see the number beside the “H” on the pencil, the larger the core, the harder the pen, the thin and shallow words.
“B” is the abbreviation of the English “BLACK”. When you see the larger number next to the “B” on the pencil, the darker the core, the thick and deep the words written.
This is because the proportion of clay mixed in the graphite is different, and the hardness and color of the pencil core are different. When you see the “HB” printed on the pencil, it means that it is moderate. The most commonly used writing options.
In the standard, the lead -related performance of the pencil has been strictly strictly regulated:
In addition to the performance of the lead core, the standard also strictly provides the diameter of the lead core and the length of the pen rod:
↑ Standard for the diameter of the lead core
Standard for the length of the pen rod ↑ ↑
In addition, the appearance requirements are also required: the pen roll performance is good, the surface of the pen rod is not obvious, and the marks can be identified.
Take you to pick a pencil
When we choose a pencil, pay attention to the following aspects:
Look at the appearance: The cross section of the pencil is flat, and the core is complete. A good pencil cross section is positive hexagonal, the plane is symmetrical, the rod diameter is uniform, the pencil is short and uniform, and the paint color is bright.
Look at the packaging: Good pencils are packed from small to large packaging, and they are printed with signs, models and other signs, and the printing is clear and complete. The inspection code is complete.
Look at the trademark: The good pencil trademark pattern is clear and clear, the outline is full, the steel printing traces are coordinated and correct, each of which is neat.
(Part of the material comes from the Internet)
Supply: Chongming District Market Supervision Bureau