When painting doors or windows, where possible remove handles and other ‘furnishings’ first. If the old paint surface is in a good condition it can be left as a sound base for painting over. Clean the surface with sugar soap and water, then lightly sandpaper, this will provide a key for the new paint. This is essential otherwise new paint can be easily scratched or damaged.
Old paint or varnish should be stripped as the lumpy, uneven surface could spoil the appearance of the new paintwork. Deterioration in the appearance of the old surface, especially if areas are in poor condition, are unsound or flaking, will ruin the new paint surface unless removed first.
If possible strip off all the old paint back to the bare wood and start again. This can be achieved by first scraping off the uneven flaky loose surface with a wire brush and then sanding, heat stripping or chemical stripping. A combination shave-hook, used in conjunction with a scraper, is a useful tool as it has pointed as well as straight and round edges, all of which are useful when stripping awkward areas. Otherwise use a triangular shave-hook (3 straight edges) and scraper. Take care not to use too much pressure, this could gouge the surface.
If some areas are in a very neglected state, it may be more expedient to replace sections of wood. Never cover up a neglected area without solving the cause of the problem. Soft patches could indicate dampness or damp rot.
Sand using glasspaper wrapped around a wooden block. It is hard work and all sanding should be in the direction of the grain in the wood. A sanding attachment can be used and for larger flat surfaces a suitable sander should be hired for speed and efficiency.
A blowtorch can be used on an old paint surface. Keeping it a short distance, approximately 50mm (2 inches) from the surface and moving around, the paint should blister. Then using a scraper or shave-hook, scrape off and deposit the discarded material safely in a metal container.
Never keep the flame pointing in the same position, always keep it moving over a small area, this will avoid scorching the wood. Be careful to cover the floor or furnishings and remove any flammable materials, such as curtains.
It is sensible to wear safety gloves and goggles. Electric hot air strippers are often used instead of the blowtorch. They are easier to handle, (similar to a very hot hair dryer) some having different nozzles suitable for difficult areas, and are unlikely to cause the surface to scorch. Once the area is stripped completely, sand the surface removing any particles of paint or scorch marks.
There is a variety of chemical strippers available falling into two main categories. The liquid or gel form, consisting of a methylene chloride base or the paste form consisting of a caustic base. They have to be carefully spread over the surface and then left for several hours. It is important to follow the manufacturer’s instructions carefully, as there are different instructions applicable to different chemical strippers. It is sensible to wear safety gloves and goggles to avoid being splashed by the chemical. It is also worth wearing a mask to avoid inhaling dangerous fumes, always ventilate indoor areas.
Remember to keep children or pets well away from the areas affected.
When the chemicals have taken effect, scrape away the surface with either a scraper, or for more detailed areas a shave-hook. Sometimes a door or wooden item can be removed completely and taken to a company specialising in industrial stripping (unsuitable for veneered items, which may peel). Some companies will collect the items and return, rehanging the doors if required. They will immerse the door completely in a tank containing hot or cold chemical solutions. This is then pressure sprayed with water to remove all traces of chemical. There can be some risks, problems caused by splitting panels, joints opening or wood warping. Cold solutions are often more expensive, but less damage is experienced.
Always prime bare wood. It is important to work with dry wood, before lightly sanding in the direction of the grain. If the wood appears oily, wash with white spirit and dry beforehand. Unless you are going to apply a clear varnish or lacquer, apply shellac knotting to knots and resinous patches to prevent bleeding and staining subsequent layers of paint.
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