How to Finish Wood with a Spray Gun
Home spraying is only moderately successful, as the ideal spraying facilities are rarely available. But where reasonably good facilities do exist, spraying gives a quality and evenness of finish, particularly with modern clear lacquers, that cannot be obtained by other methods.
A well-ventilated, dust-free, dry atmosphere is needed and an even temperature of around 16-21°C (61-70°F). Ensure that there are no naked lights.
Spraying equipment varies considerably from very expensive appliances, running into several hundred pounds, to small reciprocating electric sprays, such as those made by Burgess. The latter do not incorporate compressors but are adequate for many small jobs.
Spraying uses more paint than brush application. Most finishes have to be thinned, but make sure that you use the correct thinner for the finish. Experiment first to find the ideal consistency for any particular finish.
Technique: practice is necessary to perfect a spraying technique, so experiment first on old boxes or similar items.
While technique varies according to the equipment, air pressure and materials to be sprayed, the following is a general guide to procedure.
1. Spray at ,a uniform distance of approximately 300 mm. (12 in.) from the object.
2. Keep the gun at right angles to the object by flexing the wrist at the end of each stroke. Failure to do this results in an uneven distribution of the finish.
3. Learn to trigger the gun by practising with an empty gun. The gun should be moving before the trigger is pressed and the spray shut off as the gun reaches the end of the stroke. This blends the strokes and avoids heavy overlapping.
4. Where possible, have objects such as table tops standing almost upright; this prevents particles of dust from settling as readily as they would on a horizontal surface. Start spraying at the top and work across and down.
5. Apply only enough finish to cover the surface. It is better to apply two light coats than one heavy one which may run.
The spray equipment must be cleaned thoroughly immediately after use. Clean out with the thinners used for the particular finish or with a proprietary gun-cleaning solution. Cellulose thinners, obtainable from many garages and paint suppliers, will clean out practically all finishes, but should not be used to thin down any material other than cellulose.
Most spray finishes are extremely unpleasant to inhale and, can be harmful. Work in a well-ventilated room or workshop, wearing a face mask all the time. Masks can be obtained from most chemists.