Impregnation of Wood

Impregnation of Wood

 

the introduction of chemical substances into wood in order to improve its characteristics and impart new properties. Impregnation stabilizes dimensions, increases strength and resistance to water, moisture, and chemicals, and reduces cracking. The most common methods of impregnation employ antiseptics, which ensure protection against wood rot and other forms of biological deterioration, and fire retardants, which prevent wood from catching fire and burning. Impregnation is used in the railroad industry, power engineering, the manufacture of railroad cars, shipbuilding, and construction.

Impregnation of wood is classified as diffusive, capillary, or hydrostatic (pressure treatment), depending on the physical phenomena involved in the process. Diffusive impregnation is based on the diffusive migration of impregnants through the moisture-filled capillaries (seeDIFFUSION); only water-soluble impregnants are suitable for this method. In capillary impregnation, the impregnating fluid migrates through the capillaries in the wood under capillary pressure (seeCAPILLARY PHENOMENA). For example, in capillary impregnation using crown suction, the aqueous impregnating solution passes through openings in the lower section of the trunk or through the butt end into the sapwood of living or freshly felled tree by means of the suction force exerted by the crown. In pressure treatment, the impregnants migrate through the capillaries in the wood under artificially induced pressure. Liquid and gaseous substances are suitable for impregnation, as are melts of solid substances whose melting point does not exceed 200°-230°C.

In industry, impregnation of wood is primarily done with an autoclave under a pressure of up to 1.4 meganewtons/m2 (14 kilograms = force/cm2). The pressure treatment of unseasoned wood includes butt treatment, autoclave-diffusive methods, and successive drying and impregnation. In butt treatment, aqueous solutions are introduced under a pressure of up to 1 meganewton/m2 (10 kilograms = force/cm2) through one of the butt surfaces; in successive drying and impregnation, the wood is placed in an autoclave, where it is first dried, then impregnated. Impregnation technology requires that the wood be processed before impregnation; the processing methods include barking, mechanical working, drying, and slitting—the creation of slit-shaped openings that stimulate impregnation.

REFERENCES

Hunt, G. M., and G. A. Garratt. Konservirovanie drevesiny. Moscow-Leningrad, 1961. (Translated from English.)
Baraks, A. M., and Iu. N. Nikiforov. Glubokaiapropitka drevesiny putem primeneniia nakolov, 2nd ed. Moscow, 1969.
Konservirovanie i zashchita lesomaterialov. Moscow, 1971.

I. K. CHERKASOV

References in periodicals archive ?
Research has been done before on de-lignification and on the monomeric impregnation of wood, but never have they been combined in the way WOODOO does, with a direct and highly promising application potential across various industries.
For complete impregnation of wood flour internal mixing apparatus ran for one minute after addition of wood flour.
Previous reports of the chemical impregnation of wood using conventional fire retardants demonstrate effective biocidal properties (Mamey and Russell 2008).
Percentage volume increase after impregnation of wood samples was calculated by the formula:
The properties of the chemicals used for the impregnation of wood panels are represented in Table 2.
Preservative treatment and resin impregnation of wood
In addition sawmilling operations performed impregnation of wood products in the field.
3) Repair or replacement and impregnation of wood sealing closures.
Therefore, impregnation of wood with an appropriate water repellent or applying a varnish compatible preservative chemical prior to hazardous service conditions has been undertaken to make wood more stable against photochemical degradation, dimensional changes, biological decomposition, and fire (Yalinkilic et al.
Medium coagglomeration is observed between sawmilling and planning of wood; impregnation of wood and manufactures of wood containers (20.
The use of biological agents to improve wood permeability, resulting in homogenous impregnation of wood products, has been studied for several decades and is known as bio-incising (Johnson and Gjovik 1970).