WHY
WOOD TO
BE COATED
Wood is generally a soft and porous material that easily attracts dirt and moisture.
Coating is used to improve the resistance of the wooden surface against mechanical and chemical impacts, to assure biological protection (when used outdoors) and to make the wood surface attractive.
is to protect the surface of the wood and to give it a good appearance. Different materials are used for finishing: fillers, stains, wood-protective products, prime and finishing lacquers, primer and top coating, furniture oils and waxes.
Fillers are used to fill up cracks and small cavities in the wooden surface.
Stains are usually applied under transparent coats (lacquers, furniture oils and waxes). A stain’s purpose is to give the surface the required colour, to emphasise the natural beauty of the wood and its structure.
Wood-protective products are used for treatment of surfaces which need protection against biological influences (micro organisms, mould, insects etc.) - such as garden furniture, window frames and other exterior wooden surfaces.
Lacquers and paints are the coating materials mostly used. The main difference between lacquers and paints is the pigment content. Lacquers contain an insignificant quantity of pigments or no pigments at all, (transparent), whilst paints have a high quantity of pigments and they do therefore provide a opaque coating.
THE MAIN PURPOSE
OF COATING
In order to obtain a good appearance of the treated wood object, a lacquer/paint system is used. The system consists of:
a) For clear coat systems:
- the Sealer; characterized by e.g. easy sanding properties & a good transparency, - the Top Lacquer - characterized by e.g. hard, resistant surface properties in the intended gloss;
a) For pigmented systems:
- the Primer; -characterized by e.g. good filling and sanding properties,
- the Topcoat; - characterized by e.g. hard, resistant surface properties in the intended color and gloss.
The usage of furniture oils and waxes serves where necessary to preserve the natural appearance of the wood.
When choosing a coating it is necessary to consider the coherence or suitability of the different layers to the treated surface as well as the correspondence of the chosen coating to the properties of application, transportation and usage of the finished product.
Coating materials consist of binders, fillers, pigments, flatting agents, solvents and additives.
The main properties of coatings depend upon the binder type. Materials with binders based on amino resins, polyurethane, acrylate, polyester or nitrocellulose are mainly used for the treatment of wooden surfaces. A combination of different types of binders is often used for manufacturing a coating with special properties.