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Experiments with using wood fibers to create foamed or fuzzy materials date back to the 1940s. Waste liquids containing high concentrations of lignin (byproducts of papermaking and fiberboard production) were used as a source of lignin; carbonic acid was added during the process to foam and solidify the mixture. Foaming, on the other hand, was produced by blowing air. Other techniques were also tried. However, none achieved commercial success, and the know-how was lost. Recently, in the early 2000s, this wartime idea was revived and adapted. During World War II, sawdust was added to bread dough to conserve food supplies. In 2003, Austrian researchers utilized this idea, mixing sawdust with wheat flour and water to form dough, which was then fermented using yeast. After baking, the product was called "Wooden Bread," an industrial product rather than a food item.
The current product does not have these drawbacks. In appearance, it is a brown or colored sponge that is hard to the touch, with varying pore sizes and proportions depending on the desired density. Its sole component is wood fiber, which can be coniferous or hardwood, or virtually any source of woody bio-fibers, including agricultural waste. In the laboratory, beech and pine were used. To pulp and degrade the sawdust into fibers using a thermomechanical mill, it was ground in a fine mill at 150°C. This was then mixed with water to obtain a very finely ground wood fiber suspension. To foam the aqueous suspension, protein can be added or airflow can be applied. The product's strength depends on the cohesiveness of the wood fibers themselves. For activation, hydrogen peroxide is added, and the foamed suspension is then convection-dried at 130°C for half an hour, and then kept at 70°C overnight. (This is, of course, a laboratory process. Commercial production is ongoing.)
Different densities of foam
To be continued