Stages of Pencil Production
The cedar is harvested and the logs are sawed into rectangular blocks called pencil stock which are sent to Slat factories.
At the Slat factory the blocks are cut into what's called 'Pencil Slats', thin slices of the wooden blocks about (18.4 centimetres) long, (.635 centimetre) thick, and (6.98 centimetres) wide and are treated with wax and stain to obtain uniform colour and improve the machining and sharpening characteristics of the wood to aid future processing. The slats pass through a final inspection before being sent to pencil manufacturers all over the world.
At the pencil factory a 'Groover machine' cuts semicircular, straight, parallel grooves on the pencil slats to later fit the pencils core (lead).
While this is happening, elsewhere in the pencil factory finely powdered graphite and clay is combined together with water and mixed (the ratio of graphite to clay determines the hardness and tone of the pencil, the higher the level of graphite the softer and darker the lines, the more clay the harder and lighter the lines). The mix is then formed into more manageable pieces called 'cakes' which are left to dry for 48 hours.
After all the moisture has been dried out of the cakes they are crushed back into a powder and mixed again with water.
After all the moisture has been dried out of the cakes they are crushed back into a powder and mixed again with water.
The graphite mixture is squashed with machinery to get rid of any oxygen left (this is to stop the leads from exploding when fired later). The graphite is then extruded through a mold and comes out as a spaghetti like string while a blade is timed to cut the lead into perfect lengths.
Before the graphite pencil cores are ready to be put into there cases they are dried out and fired in a furnace at extremely high temperatures, strengthening the graphite and ensuring a complete fusion of the graphite and clay.
Once the writing cores are ready they are placed into the grooves on the slats while a second slat with glue in it's grooves is placed on top creating somewhat of a lead sandwich.
These lead sandwiches are clamped and held together tightly while the glue dries.
These lead sandwiches are clamped and held together tightly while the glue dries.
After the glue has dried the sandwiches are cut by machines into individual pencils of varying shapes (hexagonal, round, triangular) and are inspected for defects before moving on.
The next and possibly final step is the painting and stamping of the pencils. The pencils receive 4-10 coats of lacquer (depending on the desired look) and stamped with foil showing brand names, logos and the most importantly the grade of the lead (HB, 2H,2B ect)
Samples from each batch of pencils are tested for their ability to sharpen, make lines and the lead must withstand enough pressure to support the user's hand.
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