Koh-i-noor Jumbo - 12 Thick Graphite Pencils. 4B. 1820 Reviews
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Koh-i-noor Jumbo - 12 Thick Graphite Pencils. 4B. 1820 Feature
- Pencil cross section: 10 mm
- Lead diameter: 5.6 mm
- Length: 175 mm
- 4B
12 Graphite pencils: 4B.
Graphite base products are a very traditional product of KOH-I-NOOR HARDTMUTH a.s., with history dating back to 1790.
The combination of basic raw materials - low-sintering soft clays and pure, modified ground graphite powder and its complex homogenisation creates a mixture for the production of 20 gradations of graphite leads, with the scope of 8B to 10H. Soft gradations are marked with the letter B taken from the word "Black" and hard gradations are marked with the letter H, which comes from the word "Hard". There are two gradations between these two groups marked HB (HardBlack) and F (Fine).
The method of production is the same for all lengths, diameters and shapes of graphite leads. Under moist conditions, the pre-prepared mixture for the required gradation is formed into leads by stretching, which are then dried. The dried leads are burnt at a temperature of almost 1000°C and then impregnated with a mixture of fat, oil and paraffin. Special modifications to some types of lead have the possibility of achieving the aquarelle effect by washing the drawing with water. The final stage of the operation is cutting, sanding, pointing, painting and in some cases leads are marked according to the specific type of product.
The produced leads are either used independently or inserted into the appropriate type of versatile holder. The most common form is inserting the leads into wood in the form of pencils with varying types of profiles and shapes.
The mutual denominator and characteristic of these products is the high quality application of the lead on the selected type of paper, with its typical metal sparkle, caused by the basic raw material - graphite. The mineralogical essence of graphite, i.e its lamellar shape, brings an easy way of creating a soft, flowing application, which is most notable with soft gradations B to 8B.
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Aug 30, 2011 03:45:04
