Pencils are stationery that we have been exposed to since childhood
As a good partner for art students and a helper for answer sheets
I believe everyone knows the importance of pencils
But do you all know about pencils
It actually doesn't contain lead!
take it easy
Today, the editor will give you a good science popularization
The things about pencils~
The Past and Present of Pencils
The name pencil is not groundless. Because as early as the ancient Roman era, people often used lead bars to make marks, and the lead bars at that time were called pencils. But this real pencil is not very effective, not only is it light in color, but it also has great toxicity.
Until 1564, a shepherd in England discovered a black mineral - graphite (the raw material for pencil leads), which had excellent color rendering, so he used it to number his shepherd.
Soon after, merchants discovered a business opportunity by cutting graphite into strips for sale, making it convenient for people to mark in their daily lives.
Although people have started using graphite to make the prototype of pencils, they do not know that this new mineral is graphite, and because it, like lead, can leave black marks on paper, it is called "black lead". So in the early days, pens made of graphite were always called pencils, and this name continues to this day.
Understanding Pencil from Standards
Nowadays, pencils are no longer made of rough graphite in the shape of a pen, but are mechanically pressed to "coat" the pencil lead with a wooden jacket, forming the pencil we know today.
GB/T26704-2011 "Pencil" stipulates that pencils are divided into graphite pencils and colored pencils according to their lead materials, and are classified into ordinary and high-end products. Among them, graphite pencils are divided into 17 types according to their hardness, including 6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, and 9H; Colored pencils are classified according to different color combinations.
The larger the number next to the "H" on the pencil, the harder the pen lead and the thinner and shallower the words written.
B "is the abbreviation for" black "in English. The larger the number next to" B "on a pencil, the darker the pen lead and the thicker and deeper the words written.
This is because the proportion of clay added to graphite varies, resulting in different hardness and color of the pencil lead. When you see "HB" printed on the pencil, it roughly means moderate hardness, so HB is currently the most commonly used writing choice.
The standard has strict regulations on the lead related performance of pencils:
