Berol
NewellRubbermaid

The 'Lead'

Pencil 'leads' contain no lead whatever. They are made of a mixture of graphite and clay, finely ground, thoroughly mixed, and fired in ovens to produce a strong fused stick, similar to chinaware.

Graphite is pure carbon and is found in two forms. Crystalline graphite, from Ceylon and Malagasy, comes in the form of tiny silvery flakes of such oily smoothness that it is frequently used as a lubricant. Amorphous graphite, mainly obtained from Mexico, is powdery, formless and extremely black, and it is this type that is largely used in the manufacture of pencils.

Graphite is a natural lubricant. It is therefore virtually impossible to grind it small enough by conventional methods. Some years ago Berol invented a special type of mil called the attrition mill. It is based on the idea that particles of graphite should grind particles of graphite. This is done by blowing two jets of highly compressed air, containing graphite particles, directly at each other. Thus the particles of graphite grind themselves by attrition. The particles, so small that they float naturally, are gradually drawn off and collected for future use.

The Clay, which comes mainly from Bavaria in Western Germany, is similar to the type used in the manufacture of the highest grade of porcelain and china, but produces a stronger fired product. It is mixed with water and refined to remove all grit and heavier elements, leaving only the finest microscopic particles which will be mixed with the graphite.

The graphite and the clay are now mixed together in the exact proportion which determines the hardness (or degree) of the pencil. Conventionally the centre point for grading is HB; this stands for Hard and Black, and has become the most popular degree.

The more graphite that is introduced into the mixture the softer and blacker the pencil will become: this group ranges from B up to 6B; the latter degree has a far greater proportion of graphite to the clay and is much favoured by artists.

At the other extreme the more clay the harder the pencil; these are manufactured from H up to 9H. The 9H pencil contains a very large proportion of clay and very little graphite and is used mainly by stonemasons and steelworkers.

The final mixture, still suspended in water, is poured into revolving pebble mills and further mixed and ground for days until both graphite and clay are reduced to still smaller particles which are perfectly dispersed.

The mixture is then pumped into filter presses where the water is squeezed out, leaving a stiff solid, which is compressed and extruded to compact it still further.

Finally, it is extruded from a cylinder, in the bottom of which there is a diamond lapped sapphire die the diameter of the finished 'stick'. Under many tons of pressure, the mixture is forced through the die, cut into appropriate lengths and further dried ready for the final process.

When completely dry, the sticks are packed in crucibles and fired for many hours at white heat (1200oC) in electrically controlled gas or oil-fired furnaces, where they are tempered like fine steel. They come out of the furnace almost ready for use. There is one thing to be added - wax; to give an even smoother writing point. The wax is a petroleum derived product; spermaceti is no longer used. However, the stick has to be glued into the wood in such a way that it will not slip out. It is a well known fact that glue will not stick to wax unless it is specially treated.

Some years ago Berol invented a process which overcame this difficulty, with the result that the lead was in fact 'super-bonded' into the wood. The trade mark 'chemi-Sealed' assures the user that Berol pencils have been super-bonded.

Super-bonding means that the stick will not shatter inside the wood if the pencil is dropped. It means that the pencil can be sharpened without bits breaking loose and clogging the sharpener. It also means that a firm writing pressure can be exerted without the stick slipping out of the top of the pencil, frustrating the user as it did in the old days.

The Wood

Californian incense cedar wood is sawn into small slats, each the length of a pencil but half its thickness, and about nine pencils wide. After months of seasoning, the slats are run through a grooving machine which carves out parallel groves just deep enough to hold half the diameter of the stick. The grooves are then impregnated with a resinous binder that locks the wood fibres into a non-splitting sheath (this is the second half of the super-bonding process) and the sticks are laid in the grooves. Binding glue is applied to a second slat, similarly grooved, and the two slats come together under great pressure to form a 'sandwich'.

These sandwiches are washed, thoroughly dried, and fed into a shaping or moulding machine. The cutters first of all shape one side of the pencil; the sandwich is then flipped over and fed through a second moulding machine which shapes the other side. The shaping machine runs at a carefully calculated speed to give the smoothest possible surface to the wood.

The Finish

The newly formed pencils are now passed many times through small cups holding the lacquer polish until they have built up coat after coat of lacquer on the surface. The pencils are then hot-foil stamped with the brand and degree before sharpening. All Berol pencils are sharpened ready for immediate use, saving hours of initial sharpening in the classroom or office.

Coloured Pencils

Coloured pencils are manufactured in exactly the same way as graphite but without the firing process. The mixture consists of pure white kaolin, waxes, pigments and refined adhesive binders. They are intimately mixed together and roll milled to ensure a perfectly homogenous (uniform) compound. After mixing, compression and extrusion the sticks are carefully dried for long periods in air-conditioned rooms where the temperature and humidity are accurately controlled.

Basically there are two types of coloured pencil: the conventional soft variety like Colourcraft and the hard-wearing thin Verithin. Another Berol development (similar in hardness to an HB pencil), Verithin lays down a brilliant colour yet lasts much longer than conventional pencils and stands up to really tough classroom treatment.

Summary

From this brief description it will be seen that the pencil - such a comparatively simple thing lying on one's desk - is in fact the result of a highly complex series of manufacturing processes. The ingredients come from all over the world and are stringently checked for consistent quality before they are finally used in the actual manufacture.

In 120 years of pencil manufacture, Berol have always paid the highest attention to rigid quality standards. This ensures that the finished product, although mass produced at the rate of many hundreds of thousands each week, gives complete satisfaction.