The Same Recipe

Humblot was following the inventor’s process. He watched the work closely. Yet the pencils leaving his factory no longer behaved as well as the ones that had established its reputation.

The explanation, recorded in a French industrial report of 1814, lay in the material arriving at the factory. Humblot, Nicolas-Jacques Conté’s son-in-law and successor, no longer had the same supplies. Graphite from different deposits varied. Keeping the method did not necessarily keep the result.

Conté’s invention had offered France a way to manufacture good pencils without relying on the exceptional natural graphite used in the best English ones. His successor now had to make that promise work with another batch of mineral. By the time inspectors examined the renewed output, Humblot had more than fifty thousand pencils wrapped in packets, ready for sale.

Their numbers ran from 1 to 4. Number 1 was softest; number 4 was firmest. The useful question was whether a buyer could depend on those numbers.

A pencil from a mine

Before Conté, a good pencil could begin as a particularly suitable piece of graphite. The fine material from Borrowdale in Cumberland, northern England, could be cut into narrow pieces and enclosed in wood. Its ability to leave a smooth mark was a quality the maker selected from the mineral.

Graphite is a form of carbon. Its particles slip over one another and transfer to paper, where the deposit can catch the light with a metallic sheen. The familiar word “lead” survived from older descriptions of the material; the dark core of an ordinary graphite pencil contains no metallic lead.

War made the supply problem urgent. In a report read to the Institut National in 1796, Antoine-François Fourcroy and Pierre Bayen described English and German pencils as having become rarer and more expensive. The French administration wanted an alternative that could be made in quantity.

Conté brought experience of drawing materials as well as mechanics and chemistry. He had worked as a painter, experimented with colours and worked on military balloons. A pencil had to satisfy people drawing a face, a map or the lines of a building; simply making a black substance stick to paper would not answer all their needs.

Artificial pencils already existed. Fourcroy and Bayen recalled earlier mixtures that bound graphite with substances including gum, resin and egg white. Some produced an uneven grain or a fragile stick; some softened or dispersed in water. They also acknowledged better work. The engraver Lafosse’s pencils had received favourable academic reports in 1771, though the commissioners said the material dispersed readily in water and had not reached large-scale production.

Conté patented his own process in 1795. Powdered graphite was mixed with fine clay, formed, fired and enclosed in wood. The useful marking material could now be assembled from a mixture, with properties adjusted through its preparation.

Making a grade

Clay gives the fired core structure. Increasing its share generally makes a firmer pencil; more graphite makes a softer, darker one. The point of controlling the mixture is practical. A fine line needs a point that keeps its shape. A broader, darker passage needs material that comes away more readily under the hand.

That brief explanation leaves most of the work to be done. Coarse particles can spoil the feel of a line. A badly mixed paste can vary within one stick. Drying and firing have to leave a usable core rather than a brittle or distorted one. Once the material is housed in wood, the buyer still has to sharpen it without losing the point.

Fourcroy and Bayen credited Conté with twenty-six months of experiments and research. Their report, preserved in Edme-François Jomard’s 1849 biography, praises uniform material, deliberately varied properties and machinery for preparing both the core and its wooden covering. They kept the manufacturing details general to protect his proprietary methods. It was a report on the system’s results, rather than a complete factory recipe.

Another Institut report in 1796 considered what the pencils could do in a user’s hand. It distinguished four kinds for line work, ranging from rough lines drawn by inexperienced hands to the fine, light marks needed for maps, plans and architectural drawings. Four other kinds served drawing. Uncovered sticks could be shaped and held in a drawing tool for broader work; wood-cased pencils offered protection and a convenient grip.

A closer look · 2:21 · Visual demonstration

Making the core, then the pencil

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Later manufacture made those operations increasingly mechanical. An 1872 account describes fine clay being washed, mixed and kneaded with graphite, then pressed through an opening into a continuous length. The lengths were straightened, cut, dried and fired. These are details of the mature nineteenth-century process, rather than a witnessed sequence from Conté’s first workshop.

Wood had its own production line. Grooves received the cores; a covering strip was glued down; cutting and shaping brought the blank to a pencil that could be held and sharpened. An illustration published with the 1872 account shows a worker cutting and grooving the wood at a bench, with the stock still long enough to produce several pencils.

The number on the packet

Humblot’s difficulty exposed the limits of repeating instructions. The 1814 report says he needed either to adapt the treatment to different kinds of graphite or to bring them to a uniform degree of purity. It credits his subsequent improvements with restoring the quality of the pencils presented for examination.

The commission included Molard, Gaulthier and Mérimée, who served as rapporteur. They selected six pencils bearing the same number from different packets and compared them. They also checked that the intermediate grades were distinguishable from their neighbours, then compared Humblot’s products with English pencils from named manufacturers.

Number 1 could closely resemble the prized soft English material. Number 4 retained a very fine point without breaking or becoming blunt, which the testers valued for delicate graphic work. A firmer grade could save the draughtsman from constantly stopping to cut a new point. A softer one could lay down more material when that was wanted.

The report priced Humblot’s pencils at 3 francs 60 centimes a dozen; its quoted prices for premium English examples were more than twice that. It also noted that the French cores filled the wood from end to end, while the English comparison pencils contained an inch of empty space.

Those numbers were the factory’s own range. They should not be read as a direct conversion into every later maker’s H, B and HB grades. The modern pencil rack has inherited the idea of choosing a working character, rather than a universally fixed scale from 1795.

Smoothness mattered as well as firmness.

The testers described the softer grades as having an almost soapy feel. The firmer ones felt drier, but still travelled over the paper without troubling its surface. A grade could resist wear at the point and remain pleasant to draw with.

The commission also wanted a mark that could be removed. Its members reported that the pencils erased well with rubber and moved smoothly without damaging the paper. They asked experienced users to repeat the trials. The judgement concerned the pencils actually sampled, with the hope that the factory would continue supplying the same quality.

One remaining question could not be answered by sharpening a fresh point. The material had to remain uniform all the way through. To test that, the inspectors used pencils to the end and cut others into pieces. They reported finding no difference along the length.