Important Wood Properties for Formation of Protective and Decorative Coatingsof Wood and Forest Products

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UDС

684.59

DOI:

10.17238/issn0536-1036.2015.6.116

Abstract

Production of high-quality wood products is largely determined by the formation of protec-tive and decorative coatings, which currently is carried out mainly by applying of different types of paint and varnish materials. The role and importance of the lacquer coatings partic-ularly increased in the first half of the 20th century in connection with the development of industrial processes of production of wood products. Scientific and technical fundamentals of protective and decorative coatings had been built in our country only in the early 30-ies of the last century in the period of industrialization, when the nitrocellulose lacquers and pneumatic spraying method of paints and varnishes were widely used in the decoration. More significant changes in the finishing technology occurred in the late 50's – early 60's due to the great success of the polymer chemistry development. The emergence of polyester, polyurethane, urea-formaldehyde and other synthetic binders allowed obtaining fundamen-tally new powder and water-dispersible paint systems. Their low level of gloss coating and the necessity of melting of powders at temperature above 200 °C restrain the introduction of those materials in practice of wood finishing. The temperature impact on the wood causes its mineralization. Hence, it’s necessary to seek ways to reduce the melting temperature of powders, which will use them to form the protective and decorative coatings on materials, such as particle boards, MDF, plywood, as well as on the wooden parts of agricultural ma-chines, wagons, ships and cars. The paper is devoted to the review of the lacquer coatings. The scientific notations about the physical, chemical and mechanical processes that signifi-cantly contribute to the formation of high-quality protective and decorative coatings are sys-tematized in relation to the wood characteristics. The nature of the coating surface affects the coating quality more than any another property of the lacquer coating. Wood is biologi-cally unstable material. The study of the structure and properties of wood and wood-based materials is the subject of the special investigations, focused on the characteristics that have a direct impact on the results of individual operations. The features are: a capillary-porous structure with a strongly pronounced anisotropy of the structure and properties along, crosswise the tree trunk and in tangential and radial directions; the ability to dry and mois-turize and limited swelling like other colloidal solids; a complex chemical composition, hard-ness of wood, surface energy, color, texture, glaze of wood. The paper presents the analysis of wood properties, which necessary to be considered at preparing a surface for finishing, with regard to the specific physical and chemical properties of paints and varnishes. The mechanism of physical phenomena involving the ability to perceive a true color and wood texture at applying the transparent liquid materials and films on a substrate is devel-oped.

Authors

V.I. Onegin, Doctor of Engineering Sciences, Professor

Affiliation

Saint Petersburg State Forest Technical University, Institutskiy per., 5, Saint Petersburg, 194021, Russian Federation; e-mail: onegin.ltu@mail.ru

Keywords

wood, substrate, anisotropy, structure, capillaries, pores, medullary rays, nap, absorption, reflection, moistening, lacquering, color, gloss, texture, refraction.

References

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