David develops a cheap plant-based paper

David Séchard develops a cheap plant-based paper by seeking not merely a new material but a complete, economical papermaking process. His experiments move from reed-fiber sheets made with a makeshift sieve to a discovery about nettle pulp, and finally to a successful method for sizing the pulp in the vat. The invention promises to make inexpensive paper from plants growing on marshland and poor ground, but its progress is entangled with debt, the risk of losing the process to competitors, and David’s father’s refusal to fund him before the results are complete.

The search for an inexpensive material

David’s aim is to lower the cost of paper at its source: the pulp. He explains to Ève that making sheets is not the central difficulty; the price of the pulp is. Earlier experiments had already shown that paper could be made from printed sheets and from straw, but David regards those precedents as insufficient answers to the problem of affordable production. In particular, he distinguishes the existence of a workable material from a method cheap enough to make it commercially useful.

He turns to plants that can grow on marshes and poor land, where the raw material would be available at very low cost. Common reed, identified as arundo phragmitis, has already yielded sheets. David also intends to try nettles and thistles, concentrating on how their stems can be prepared for papermaking. His ambition extends beyond a single successful sample: he hopes the process will give French papermaking a national advantage, and imagines becoming its Jacquard, a reference to transforming an industry through invention.

Early sheets and the limits of the first method

David shows Ève samples of white paper made with a horsehair sieve borrowed from Marion. He estimates that a ream in the large raisin format could cost no more than five francs. The sheets make the possibility tangible: rather than speaking only of an invention still to come, he can put examples into Ève’s hands and let her inspect them. Her surprise and admiration meet his disclosure that the result is close, but not yet complete.

The first obstacle is the binding quality of plant pulp. David has been trying to replace the breaking and working processes associated with turning fibers into thread, cloth, or rags with equivalent procedures for making paper. After soaking a nettle stem, he chews it while walking from his home to Pierre Petit-Claud’s office. A ball of pulp forms in his mouth. When he removes it and spreads it on his hand, he recognizes a mixture better than the compositions he has previously obtained: it has addressed the lack of binding that makes vegetable pulps troublesome. Straw, for example, can produce paper that is brittle, nearly metallic, and sonorous.

The discovery arrives through an accidental bodily action, but David immediately treats it as a technical clue rather than a finished solution. He proposes replacing the operation he has performed unconsciously with the action of a machine and a chemical agent. The episode gives the material itself a decisive role in the development of the invention: the nettle pulp reveals a property that deliberate trials had not yet secured, while David’s work lies in understanding and reproducing that effect.

Sizing, patents, and the unfinished invention

Even with a cheap vegetable pulp, the paper still needs to be sized. David knows that a patent alone may not protect an inventor’s livelihood: a competitor can make a small improvement, such as changing a screw, and claim the improved process. The danger is especially clear in his case, because inventing inexpensive pulp does not exhaust the possible improvements to paper manufacture. He wants to anticipate those refinements rather than see the fortune he has pursued taken out of his hands.

His particular target is sizing the pulp in the vat. In the account he gives of Dutch paper, the sheets are lightly sized, but the sizing is applied sheet by sheet, with labor that raises the price. If an inexpensive adhesive could instead be mixed into the vat, the process would avoid that costly handwork. David has spent a month trying to achieve this. He is thus pursuing two related industrial secrets: low-cost plant pulp and an economical way to size it evenly before the sheets are formed.

When Marion urges him to earn money to pay what he owes before continuing to hunt for his discoveries, David insists that the last difficulty will be overcome. He wants both an invention patent and a patent of improvement. The distinction reflects his concern that a rival might appropriate the work through a modification, but it also reveals the cost of trying to secure the invention fully: each remaining technical problem extends the time before he can turn it into income.

Proof, resistance, and the successful process

David’s financial circumstances make that delay consequential. While explaining his paper to Ève, he imagines that their prospects will change once he has made Lucien rich; Ève answers that Lucien’s weakness makes him vulnerable to temptation and that David should not mistake affection for strength. David says he will spare Lucien the struggle, then lays out the paper samples and his plans. The exchange places the invention within a household trying to protect someone it loves, even as its own resources are under pressure.

Later, David brings about thirty sheets to his father after working through the night in the brûloir. The samples are fine, white, firm, and strong, bearing in their watermarks the differing marks of the horsehair sieve. Jérôme-Nicolas Séchard tests them by touch and by the practical procedures used by printers to judge paper, yet refuses to concede that the results are good enough. He asks what the paper will become under the press. David himself acknowledges that the current paper may still cost too much and identifies vat sizing as the one remaining advantage he has to secure. He admits that he can size the pulp in the vat, but the glue does not penetrate it evenly, leaving the surface rough like a brush. His father makes further funding conditional on correcting that defect.

The breakthrough is eventually conveyed to Ève in a letter written on the first sheet made by the completed process. David tells her that he has solved vat sizing. Even allowing for the special cultivation of good land for the plants he uses, a pound of pulp costs five sous; a twelve-pound ream therefore contains three francs’ worth of sized pulp. He calculates that the process can cut the weight of books in half. The letter and the accompanying samples are made by different versions of the process, turning the announcement into evidence that can be compared and examined.

Ève carries the samples to Jérôme-Nicolas and asks him to give his son the price of his crop, promising that David will return ten times what he receives. The old man takes the examples to the Cointets, where they are tested and closely inspected. Some are sized and some unsized; their stated costs range from three to ten francs per ream. Their finishes also differ: some are metallic in purity, others soft like Chinese paper, and the samples show many shades of white. The invention has therefore advanced from the first rough trials to a varied set of specimens that invite commercial scrutiny. Its achievement is not simply that plants can yield paper, but that David has brought the material cost, weight, and sizing process into a single practical proposal.