Interior Decoration: Preparation for Painting
Cleaning Down Surfaces:
If the old surface is painted wood which is in a reasonably good condition, it should first be washed with warm water and sugar soap. The surface should be well rinsed with clean water and left to dry before rubbing down and applying the first coat of paint.
Rubbing down is done with glass-paper folded round a block of wood or cork. The glass-paper may be from grade one to grade middle-two, according to the condition of the surface of the work — the lower the glass-paper grade-number, the finer the abrasive surface. For moulded surfaces the block should be shaped to fit the contours of the moulding. A soft 4-in.-wide brush is used for cleaning surfaces of sanding dust. The glass-paper — and all tools employed for preparing wood surfaces — is always used in the longest direction of the work.
If the old surface of painted woodwork is in poor condition — lightly pitted and blistered — it should be scraped with a shave-hook, the irregularities later being filled with a patent compound to the level of the surrounding surface. Shave-hooks are obtainable with headblades of three different shapes — triangular, pear-shaped and multi-shaped. The multi-shaped shave-hook is the most suitable tool for general use.
Stripping Old Paint:
If the painted woodwork is in very bad condition — thickly encrusted with numerous layers of old paint which have become badly blistered and scored — it will be necessary to strip down to the bare wood. This may be done in one of three ways: (1) by scraping, (2) by using a solvent, (3) by burning.
Scraping is a lengthy and tedious process which must be done carefully to avoid cutting into the wood with a shave-hook. It may be confined to blistered parts of old paintwork — usually window-frames — the raised edges of blister-pits being cut down with a flat-sided pumice-stone, lubricated with water.
Paint solvents are corrosive and must be used with care. There are several good proprietary brands — usually labelled ‘paint removers’ — which should be used according to container instructions. Apply solvent with an old brush, treating a small area at a time. Leave until paint wrinkles, scrape softened paint from wood with a shave-hook or stripping knife. The basic tool outfit should include three knives with blades of different widths-1 in., 2-1/2 in. and 4 in. measured across the cutting edge. The solvent used must be thoroughly neutralized before painting the wood; in most cases petrol is the best neutralizer, but this may vary according to the make of solvent used, and the handyman is advised to read container instructions carefully before using a paint solvent.
Solvents are suitable for stripping paint from small areas of woodwork, but they may be found costly in use for treating large areas — also uneconomical in the expenditure of time. Large amounts of badly-surfaced woodwork are best stripped by burning off. This may be done with an electrically-heated tool or with a blowlamp. An electrical paint-stripper consists of a small reflector bowl affixed to a handle; one or two elements are fitted inside the bowl which is covered by a wire-mesh guard that prevents the source of heat being brought too close to the working surface. The tool may be plugged into any source ofsupply of the same voltage as the tool. The stripper is then moved over the surface of the work and the softened paint is removed with a shave-hook or stripping knife. The butane-fuelled blowlamp is considered the safest for home use and is less complicated to operate than a paraffin fuelled blowlamp.
The butane lamp consists of two main parts — a cylinder of butaneand a ‘gun’. The cylinder is fitted with a threaded cap that unscrews to expose a simple valve. The connecting socket of the gun is also threaded to over the top of the container, opening the valve which is regulated by a knurled knob which is positioned at the back of the gun, over the pistol grip. The gun is screwed tightly on to the cylinder, the knurled knob turned anti-clockwise by finger pressure, and the lamp lights instantly when a lighted match is held under holes drilled in the barrel near the nozzle. The intensity of the flame is easily regulated to suit the type of job — a small flame for burning off sash mouldings round windows, a fiercer flame for large, flat surfaces. A multi-shaped shave-hook and a medium-broad stripping knife are used to strip the paint softened by the flame of the blowlamp. Note that the tool follows the flame. The difference in use between a shave-hook and a stripping knife is that the former is used mainly on mouldings and narrow surfaces and is pulled against the softened paint, while the stripping knife is used on large, flat surfaces and is pushed into the softened paint.
In a paraffin blowlamp the fuel container is fitted with a pressure pump and this is worked to increase the pressure in the chamber so that the paraffin is forced through a small hole into the firing nozzle, which is similar in shape to the nozzle of a butane-fuelled blowlamp, and the vaporized fuel is automatically mixed with air. It also has a simple valve which controls the flow of the paraffin fuel under pressure. Unlike the butane blowlamp the paraffin lamp does not ignite immediately, and it is necessary to heat the nozzle so that the spray of paraffin automatically mixes with the air drawn through the nozzle vents. This heating to commence burning is effected by soaking a piece of rag in methylated spirit and wrapping this round the nozzle of the lamp; the meth-soaked rag is then touched off with a lighted match and after a few seconds the nozzle is warm enough to ignite the fuel by opening the fuel valve of the blowlamp, which should then produce a fierce, clear flame. The strength of the flame can be regulated by adjusting the control valve; when the flame loses its strength more air is pumped into the fuel container.
The handyman-decorator should develop the good habit of using a paint-kettle. This is a container into which mixed paint is poured. It is made of galvanized iron and fitted with a substantial handle. The use of a paint-kettle enables the paint to be handled more easily than from a paint-tin and there is less likelihood of knocking the paint-kettle over than a tin of paint. Also, for the upper part of rooms and exteriors where it is necessary to carry the paint, the use of a paint-kettle will be found advantageous. In the case of small jobs requiring only a small amount of paint, the tin may be placed in the kettle and held in place by inserting strips of rolled newspaper between the outside of the paint-tin and the inside of the kettle. Paint-kettles should be cleaned after every job, by tipping any paint left over back into the container and wiping the inside of the kettle with a rag dampened with turps substitute. If paint is allowed to harden inside the kettle, this may be removed by burning a turps-soaked rag in the kettle and scraping the inside surface with a putty knife as soon as the heat softens the paint.
A putty knife is, as its name implies, used mainly for working putty. Either for finishing edges over windows when reglazing, or for filling holes and cracks in woodwork. A good quality putty knife will have a flexible blade.
Cleaning materials consist mainly of old pieces of rag, invaluable for many interior decorating jobs, and perhaps a decorator’s cellulose sponge.
Most important is a sturdy step-ladder of a sensible height to permit easy access to the topmost decorating surfaces of rooms. A wire brush will be found useful, especially when preparing metal windows for painting. A wire brush has many uses for exterior decorating.