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Does pencil chewing really lead poisoning? The truth is here...

Source: Time:2018-07-11 19:27:08 frequency:

In fact, people who have this doubt often think that lead in pencil lead, the use of lead pencils, naturally lead poisoning. So, does the pencil lead contain lead? To answer this question, we have to start with the origin and development of pencils.
Will long-term use of pencils lead poisoning? This problem often troubles some people.

In fact, people who have this doubt often think that lead in pencil lead, the use of lead pencils, naturally lead poisoning.

So, does the pencil lead contain lead? To answer this question, we have to start with the origin and development of pencils.

In the 16th century, a black mineral, graphite, was discovered in Borrowdale, England. Soon, some local shepherds found that graphite could be used to mark sheep.

Inspired by this, people cut large pieces of graphite into small strips for writing and painting, but graphite strips easily dirty hands, and easy to break, in addition, pure massive graphite ore is very rare.

Later, a German scientist in Nuremberg proposed a method of preparing graphite strips from powdered graphite.

He mixed sulfur, antimony, rosin and other substances into graphite powder, then heated and solidified the mixture and pressed it into the shape of a pencil, which was the earliest prototype of pencil.

At this time, only two countries in the world, Britain and Germany, can make pencils. After Napoleon launched a war of aggression against his neighbours, the two countries cut off the supply of pencils to France.

The French don't have pencils to use. What can we do about it? One officer in Napoleon's army, Nicolas-Jacques Cont?, finally explored a new way to make pencils after repeated experiments. He mixed clay in graphite and barbecued it in a kiln to make a very durable pencil lead in the world at that time.

The pen core produced by this method is stronger and wear-resistant than the original pure graphite block, and this method can be applied to any graphite ore, changing the dependence on pure block graphite.

This method has been used until today. We can see that H (hard pencil), B (soft pencil) and HB (moderate hard pencil) on the pencil mark actually indicate the hardness of the pencil core. The hardness and color of the pencil core are different when the proportion of clay in graphite is different.

The problem of the pen core has been solved. When did the wooden pole coat outside the pen core be added?

It is said that at the beginning of the 19th century, a carpenter in Massachusetts named William Munroe added a wooden pole coat to the pen core. He carved a groove in the wood, then embedded a pencil core, then glued two pieces of wood together to make a pencil with a wooden pole coat. Since then, many pairs of pencils have made pencils with a wooden pole coat. The pencil is the same as the pencil we are using now because of the improvement of the manufacture of the pencil core and the insertion technology of the pencil core.

Seeing this, some people may have another question: the production process of pencils, lead is not used at all, so why call it a pencil, rather than a "graphite pen" and so on?

This is because in the early years when graphite was discovered, the subject of chemistry was still very immature. People lack accurate understanding of graphite as a new thing. They think that they found lead ore and named graphite "lead ore".

In this way, the pen made of "lead ore" is naturally made into "pencil". This ambiguous name is used in German, Irish and other languages.

Real understanding of the nature of graphite is a later thing. With the continuous development of natural science, people find that this kind of black, slightly greasy material is made up of layers of carbon atoms, and it and diamond are "relatives". Both elements are carbon, but carbon atoms in diamond. The arrangement is different, which is also the fundamental reason for the huge difference in color, hardness and other properties between the two.

Since there is no lead in the pencil lead, is it absolutely safe to use a pencil?

Some people often hold the pencil in their mouth when they use it, even bite it twice. In fact, for those who have the habit of biting pencils, we should pay more attention to it and get rid of it.

This is because the wooden poles of pencils are usually coated with colorful pigments. If the pigments contain trace heavy metals or other harmful substances, these harmful substances often enter the human mouth during the biting process and then are swallowed by the human stomach.



To sum up, there is no lead in the pencil lead used by everyone. Therefore, correct use of pencils will not lead to lead poisoning.

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