Bois Durci in 1863

The Scientific and Industrial Year - 1863

This account is a translation of an article, in French, in a yearbook (The Scientific and Industrial Year), published in 1863.

A songwriter named Lepage had the remarkable idea , several years ago, of mixing sawdust with ox blood and compressing the mixture. In this way he obtained an extremely hard material with which he fashioned a pipe. This rough sample was sufficient to prove the importance of this new process. Messrs. Talrich and Latry after having decided together the basis of the new industry, took out a patent in 1855. M. Latry, already the owner of apparatus for the manufacture of zinc white, commenced the manufacture of Bois Durci in his Grenelle factory.

 The sawdust of Brazilian Rosewood gives the best result. This sawdust is sieved, then mixed with 15 or 20 percent, by weight, of liquid blood. The paste which results, is dried in a stove maintained at a constant temperature of 45 degrees and then reduced to a powdery state. It is in this state that it is put into the moulds by which it should take its shape. These moulds, made in malleable iron or in steel, to give the required design and fineness of the detail, are put in iron frames placed in between the two posts of a strong hydraulic press.

 Under the influence of around 600,000 kg. and a temperature of 150 to 250 degrees the wood powder binds and acquires considerable density while penetrating, with the greatest of accuracy, the various cavities of the mould. These are heated from below by pieces of iron 80 cm. long and 6 cm. diameter previously taken to red heat.

 At the end of a half hour the moulds are removed and plunged abruptly into cold water. The moulded wood, at that time, completely resembles ebony in colour and density. Thus, one cubic decimetre of sawdust weighed 800 grams before the operation; the same volume of Bois Durci weighs 1300 grams after the operation. The wood thus obtained may be worked with a lathe, a saw, burin etc. just like the hardest natural wood, and acquires a polish which makes it appropriate for the creation of the most varied objects of art or fantasy.

It was asked if it was the great quantity of resin held in the Brazilian Rosewood which had been responsible for the cohesive force of the particles of wood, and so the operation already described was done on the sawdust only, not mixed with ox blood. One obtained this time a hard and resistant product, but well below that of the preceding. This would, in fact, disintegrate easily in boiling water, while that prepared with blood resists perfectly the action of a prolonged boiling.

Although the albumen ought to be destroyed at the elevated temperature to which the moulds are taken, we must think that there had previously been so intimate a combination between the wood and the organic molecules of the blood that the strength of the wood, in other words it's resistance to mechanical agents, had been considerably increased.

We find now in commerce, and at low prices: statuettes, medallions, and objets d'art, made of this wood, resistant and unalterable in air, which are well superior to various titles of the same genre, moulded in earthenware or plaster. The caskets, inkstands, purses, frames, etc. and the other delicate objects made by the same means, are not challenged for elegance, or the finish of details, by the most well finished of sculptures.