Why is a simple pencil called "simple"? How do they mark the hardness of a pencil in different countries?

In everyday life and work, each of us, in varying degrees, need pencils. For people of such professions, as an artist, engineer, technologist, designer and draftsman, it is important such value as hardness of a pencil.

History of the appearance of pencils

In the XIII century, the first prototypes of pencils, made of silver or lead, appeared. It was impossible to erase what was written or painted by them. In the XIV century, a rod made of clay black shale, which was called an "Italian pencil", was used.

In the XVI century, in the English town of Cumberland, shepherds accidentally stumbled upon a deposit of material, very similar to lead. The bullet and shells from it could not be obtained, but it turned out beautifully to draw and label the sheep. Of graphite steel began to make thin rods, sharpened at the end, which were not suitable for writing and were very dirty.

Somewhat later, one of the artists noticed that drawing with graphite sticks, fixed in the tree, is much more convenient. That's how the case with simple slate pencils appeared. Of course, at that time no one thought about the hardness of the pencil.

Contemporary Pencils

The kind in which pencils are known to us today, invented in the late 18th century by the French scientist Nicola Jacques Comte. In the late XIX and early XX century. Several important changes were made to the design of the pencils.

Thus, Count Lothar von Faberkastl changed the shape of the pencil body from round to hexagonal. This made it possible to reduce the rolling of pencils from various inclined surfaces used for writing.

And the American inventor Alonso Townsend Cross, thinking about reducing the amount of consumable material, made a pencil with a metal casing and a graphite rod, put out to the desired length.

Why is hardness so important?

Anyone who draws or draws 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 specialties, because first any drawing is done with hard pencils, for example T2, and at the final stage - softer, with M-2M marking, to increase the clarity of the lines.

Equally important is the hardness of the pencil for artists, both professionals and amateurs. To create sketches and sketches, pencils with soft slates are used, and for a final revision of the work - more solid.

What are pencils like?

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

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

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

• Ordinary colored, which can be either one-sided or two-sided;
• Wax;
• Coal;
• Watercolor;
• Pastel.

Classification of simple graphite pencils

As already mentioned, simple pencils have a graphite pencil. Such an indicator, as the hardness of the pencil lead, is the basis for their classification.

In different countries, various markings are used to denote the hardness of pencils, of which the most widely used are European, Russian and American.

The Russian and European markings of black-graphite, also referred to as simple pencils, differ from the American one by the presence of both alphabetic and numeric designations.

To denote the hardness of a pencil in the Russian marking system, it is assumed that: T - solid, M - soft, TM - medium. To clarify the degree of softness or hardness, numerical values are introduced, next to the letters.

In European countries, the hardness of simple pencils is also denoted by letters taken from words characterizing hardness. So, for soft pencils the letter "B" from the word blackness (black) is used, and for hard pencils the letter "H" from English hardness (hardness) is used. In addition, there is also a marking F, coming from the English fine point (thinness) and showing the average type of pencil. It is the European system of marking letters with hardness 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 only digits. Where 1 - soft, 2 - medium, and 3 - hard.
In the event that no marking is indicated on the pencil, then by default it refers to a hard-soft (TM, HB) type.

What determines the hardness?

Today kaolin (white clay) and graphite are used to make the lead of the graphite pencil. The hardness of the pencil depends on the proportions of these substances mixed at the initial stages of production. The more laid the white kaolin clay, the harder the pencil turns out. If the amount of graphite is increased, the lead will be softer.
After mixing all the necessary components, the resulting mixture is fed to the extruder. It is in it form the rods of a given magnitude. Then the graphite rods are fired in a special furnace, the temperature of which reaches 10 000 ⁰ C. After roasting, the rods are immersed in a special oil solution, creating a surface protective film.