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|PAINT AS A FINISH|
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|Paint is essentially the same as varnish, although it contains coloured pigments. Paints are applied with a brush or spray gun and add a protective layer to the surface. Paints are available as matt, silk and gloss finishes and they are either water based or oil (solvent) based. Unlike many other finishes that enhance the natural grain of the wood, paints hide the grain.|
|PRIMERS, UNDERCOATS AND TOP COATS|
|Paint primer is required to seal the wood, so that there is a stable base for the application of the next paint, which is undercoat. Undercoat is supplied in a restricted range of colours and is selected according to the colour of the final top coat. The undercoat blocks all blemishes, grain and marks, providing a blank canvas for the top coat. The top coat provides the final finish, in terms of the colour and whether it is matt, silk or gloss.|
|WATER BASED (ACRYLIC EMULSIONS) OR SOLVENT (OIL) BASED?|
Paints are categorised is being water or oil (solvent) based.
Water based paints (acrylic paints) are much more environmentally friendly. They dry more rapidly and do not produce the amount of odour associated with solvent based paints. After use, brushes and equipment can be cleaned in soapy water. These paints are supplied in a wide range of colours and shades.
Solvent based paints are more damaging to the environment and the health of humans. Brushes and equipment have to be cleaned with thinners or white spirit, which is also damaging to the environment. When these paints are drying the solvents evaporate, releasing volatile organic compounds (VOCs) into the atmosphere. However, these paints generally give a superior finish, that lasts much longer than the water based paints, especially if painting is outside.
Spray paints (in the form of spray cans) can be bought straight off the shelf of most hardware stores. The preparation of the surface to be sprayed, is the same as any surface requiring a finish. In addition, a primer and an undercoat may still be required. The advantage of this system, is that the spray can be used straightway. Spray cans are often used to spray large areas relatively quickly. If used carefully, they deliver a high quality finish. They are a very convenient delivery system for paint.
One disadvantage, is that the cans are disposable, but they are difficult to recycle. They contain a compressed gas (liquefied petroleum gas) that acts as the propellent for the paint. The gas is environmentally unfriendly, but much better than the CFC (chlorofluorocarbons) gases, that were used until the 1980s. These were widely blamed for serious damage to the earth’s protective ozone layer. The cans also contain ball bearings, that when shaken, mix the paint before it’s application. All this makes it difficult to recycle used cans.
|SPRAY COMPRESSOR SYSTEM|
|Compressor based spray systems are widely available. These use a motorised compressor to compress air, which is stored in a ‘receiving tank’. The compressed air is released in a controlled manner, through a spray gun. As the air flows through the spray gun, paint is released from the paint reservoir. The paint is delivered through the nozzle of the spray gun, onto the surface being coated.|
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