A method for not only preserving cellulose material from deterioration and from fire, but also for producing plywood, chip and particle aborad with an inexpensive and environmentally acceptable adhesive is described. The cellulose material is processed by spraying, immersing or being subjected to vacuum and pressure application in two steps. One step processes the cellulose material with a sodium silicate preservative solution. Another step processes the cellulose material with a gaseous carbon dioxide. Pressure application, moreover, can be varied in a range not to exceed 250 psi to improve product quality. Moistened cellulose material, treated in the foregoing manner, is coated with a comminuted protein, e.g. soybean meal, and pressed into a cellulose product, typically plywood and chip board.
