Why is a simple pencil called "simple"? How is the hardness of a pencil marked in different countries?

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

In everyday life and work, each of us, to one degree or another, needs pencils. For people of such professions as an artist, engineer, technologist, designer and draftsman, such a value as the hardness of a pencil is important.

The history of pencils

In the 13th century, the first prototypes of pencils made of silver or lead appeared. It was impossible to erase what was written or drawn by them. In the 14th century, they began to use a rod made of clay black slate, which was called the "Italian pencil".

In the 16th century, in the English town of Cumberland, shepherds accidentally stumbled upon a deposit of a material that looks very similar to lead. It was not possible to get bullets and shells from it, but they were excellent at drawing and marking sheep. They began to make thin rods from graphite, sharpened at the end, which were not suitable for writing and were very dirty.

Somewhat later, someone fromartists noticed that it is much more convenient to draw with graphite sticks fixed in a tree. This is how simple slate pencils got a body. Of course, no one thought about the hardness of a pencil at that time.

Modern pencils

The look in which pencils are known to us today was invented at the end of the 18th century by the French scientist Nicolas Jacques Conte. At the end of XIX and beginning of XX century. several important changes have been made to the design of the pencils.

So, Count Lothar von Fabercastle changed the shape of the pencil body from round to hexagonal. This has helped reduce pencil rolling off the various sloping surfaces used for writing.

And the American inventor Alonso Townsend Crossa, thinking about reducing the amount of consumable material, made a pencil with a metal body and a graphite rod that extends to the desired length.

Why is hardness so important?

Any person who has drawn or drawn something at least a couple of times will say that pencils can leave strokes and lines that differ in color saturation and thickness. Such characteristics are important for engineering speci alties, because at first any drawing is done with hard pencils, for example T2, and at the final stage - softer ones, marked M-2M, to increase the clarity of the lines.

The hardness of the pencil is no less important for artists, both professionals and amateurs. Soft lead pencils are used to create sketches and sketches, and forthe final work of the product is more solid.

What are pencils?

All pencils can be divided into two large groups: simple and colored.

A simple pencil has such a name because it is structurally very simple, and it writes with the most ordinary graphite lead, without any additives. All other types of pencils have a more complex structure and the mandatory introduction of a variety of dyes.

There are quite a few types of colored pencils, the most common are:

• regular color, which can be both single-sided and double-sided;
• wax;
• coal;
• watercolor;
• pastel.

Classification of simple graphite pencils

As already mentioned, graphite leads are installed in ordinary pencils. Such an indicator as the hardness of a pencil lead is the basis for their classification.

Different countries have adopted different markings indicating the hardness of pencils, of which the most common are European, Russian and American.

Russian and European markings of black lead, as ordinary pencils are also called, differ from the American one in the presence of both letter and number designation.

To indicate the hardness of a pencil in the Russian marking system, it is accepted that: T - hard, M - soft, TM - medium. To clarify the degree of softness or hardness, numerical values \u200b\u200bare entered next to the alphabetic values.

BIn European countries, the hardness of ordinary pencils is also indicated by letters taken from words that characterize hardness. So, for soft pencils, the letter “B” is used from the word blackness (blackness), and for hard pencils, the letter “H” is used from English hardness (hardness). In addition, there is also an F marking, coming from the English fine point (thinness) and showing the average type of pencil. It is the European letter hardness marking system that is considered the world standard and is the most common.

And in the American system, which determines the hardness of pencils, the designation is carried out only in numbers. Where 1 is soft, 2 is medium, and 3 is hard. If no marking is indicated on the pencil, then by default it belongs to the hard-soft (TM, HB) type.

What determines hardness?

Today, kaolin (white clay) and graphite are used to make graphite pencil leads. The hardness of the pencil depends on the proportions of these substances mixed at the initial stages of production. The more white kaolin clay is laid, the harder the pencil is. If the amount of graphite is increased, then the lead will be softer.

After mixing all the necessary components, the resulting mixture is fed into the extruder. It is in it that rods of a given size are formed. Then the graphite rods are fired in a special furnace, the temperature of which reaches 10,0000C. After firing, the rods are immersed in a special oil solution that creates a surface protective layer.film.