Blackwing Graphite Guide

Have you ever wanted to try out a new Blackwing or test which graphite best suits your needs? The Blackwing Audition Pack comes with one of each core Blackwing pencil for you to try out. Every Audition pack also includes a one-time $10 discount for a future purchase of a 12-pack of our core pencils.

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What is graphite?

Graphite is a naturally occurring modification of carbon (chemical formula: C). Its atoms arrange themselves in the hexagonal pattern, which is typical for carbon, and thus form a hexagonal layered lattice. Graphite gets its typical grey color from its opaque grey to black crystals.

While diamond, another carbon modification, is the hardest naturally occurring material in the world with a value of 10 on the Mohs hardness scale, graphite is one of the softest with a value of 1-2. The different properties of graphite and diamond result from their structure:

Structure and properties of graphite

Graphite has a layer structure. In each layer each carbon atom is bound to three others. This results in a two-dimensional network of hexagons. Within each layer there are strong bonds, but between the different layers the bonds are very weak. Thus, the layers can easily be shifted against each other and even separated. This structure is the reason graphite is very soft and is even used as a lubricant. But graphite has other special properties as well:

Electrical conductivity of graphite

The fact that graphite is electrically conductive results from its atomic structure. Each carbon atom in a graphite crystal has four valence electrons, also called outer electrons, which can form bonds with neighboring atoms. However, only three of the four valence electrons enter into a bond, while the fourth electron remains freely mobile and thus allows electricity to be conducted.

Thermal conductivity of graphite

Graphite has excellent thermal conductivity combined with high temperature resistance. Graphite does not have a melting point; it changes from the solid state directly into the gaseous state. This process is called sublimation. In an inert gas atmosphere, graphite becomes plastically deformable starting at a temperature of °C. At temperatures above °C graphite sublimates even without the presence of oxygen.

Chemical resistance of graphite

Graphite is one of the most chemically resistant materials. It is resistant to almost all media of organic chemistry. These typically include the intermediate and/or end products in the petrochemicals, coal refining, plastics industry, the production of paints, coatings, refrigerants and antifreeze, but also in the cosmetics and food industries. Graphite is also resistant to most inorganic media, such as non-oxidizing acids, alkalis, aqueous salt solutions and most technical gases.

Download: Chemical resistance of natural graphite

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Synthetic Graphite

In the production of synthetic graphite, its later properties can be specifically influenced. Above all, the grain size of the graphite powder and the pressing method play an important role.

The synthetic production of graphite is technically possible since the end of the 19th century. In December , a patent for the graphitization of carbon was registered in the USA. The electrographite obtained in this manufacturing process was then used as a current-transmitting element in the form of electrodes and graphite thus became increasingly important for a wide range of industries.

The basis for synthetic graphite is formed by two raw materials: a carbon carrier that is as pure as possible, usually coal from crude oil, and pitch as a binder. The two raw materials are mixed to form a homogeneous mass and then processed and refined in complex high-temperature processes. The processes vary depending on the desired properties and type of synthetic graphite. This way, a process can be reproduced in the shortest possible time for which nature takes several million years.

Types of synthetic graphite

Fine-grain graphite

Some special property combinations of graphite can only be obtained if fine-grained solids are used. Therefore, the so-called fine-grain graphite was developed, which is produced by a grinding process. Fine-grain graphite is graphite with a grain size of less than 1 mm. Some fine-grain graphite even has a grain size of less than 1 µm. 

Isostatic graphite

The term "Isostatic graphite" stands for isostatically formed graphite. This means that the raw material mixture is compacted into rectangular or round blocks in a so-called cold-isostatic press (CIP). Compared to other techniques such as extrusion or vibration molding, this technology can produce the most isotropic form of synthetic graphite. In addition, isostatic graphite generally has the smallest grain sizes of all synthetic graphite.

Today, iso graphite represents a large part of the fine-grain graphite market and has found applications in over 30 different industries, from nuclear and metallurgical applications to semiconductor, solar and many others.

SIGRAFINE® isostatic graphite

Why does the lead pencil contain graphite?

The lead pencil has been used in many countries since the 17th century. At that time, however, the graphite used for writing was still thought to be lead ore, which incorrectly gave rise to the name “lead pencil”. A pencil actually doesn’t contain lead – but until today it is made of a graphite-clay mixture. Writing and drawing can be done so well with a pencil because graphite leaves a grey deposit on surfaces like paper. A pencil stroke is therefore a thin graphite deposit.

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