Sanford Corporation is a leading manufacturer of writing instruments of all kinds. In the 1990s, Sanford bought Empire Berol and Faber-Castell USA, to become the owner of many pencil brands, including Eberhard Faber, Berol, Empire, Blaisdell, and others. Most of the pencil manufacturing equipment of these companies was brought to the existing plant (formerly Eberhard Faber) in Lewisburg, Tennessee. In June, 2004, I had the privilege of touring this facility while vacationing in the area. Many of the photographs below can be enlarged by clicking on the image.
FIG. 1. Graphite/clay mixture
FIG. 3. Leads are cut to length
FIG. 5. Thousands of leads ...
FIG. 7. Wax vats
FIG. 2. Mixer
FIG. 4. Tray of cut leads
FIG. 6. The kiln
FIG. 8. Colored core mixer
My tour began in the mixing area, where raw materials are mixed to produce the pencil cores. The facility produces over 700 different types of pencil cores, from graphite to colored pencils (not all at the same time). Figure 1 shows a batch of graphite-clay mixture. Powdered graphite and finely ground clay are mixed with water in a large mixer (Figure 2) until it it reaches uniform consistency. The ratio of graphite and clay determines the hardness grade of the finished pencil. The mix is wet with a smooth and soapy feeling. The mixer is a heavy piece of machinery containing rotating arms that stir the mud-like mix. I noticed during this part of the tour that the concrete floor was black and slippery, though my guide assured me that the floors were cleaned periodically. The graphite dust is very dry and easily escapes its containers during this part of the processing. The slippery nature of graphite makes it useful as an industrial lubricant.
The graphite mixture is put into a press where it is squeezed through a die into long 'strings'. These strings are cut to length (Figure 3) and collected in trays (Figure 4). At this stage, the pencil leads are soft and bendable. As they are handled, they are rolled to keep them straight. I saw trays containing many thousands of leads awaiting the next stage of processing (Figure 5). The cut pencil leads are baked in a kiln (Figure 6) over a period of about 24 hours. This bakes away any remaining water and fuses the graphite and clay mixture. Some leads are then immersed in molten wax (Figure 7) to add strength and smoothness. Figure 8 shows the mixing tank for one of Sanford's colored pencil types. This mix resembles Play-Doh in a taffy puller.