New Work
Careful preparation of the surface is essential for a good result. Blemishes will show through eventually if not at once. This means that nail holes, cracks, etc., must be made good, and all roughness smoothed out. For work of first importance the surfaces should be cleaned up by hand because the machine planer or spindle invariably leaves ridges across the grain which show through later.
KNOTTING. Most softwoods contain some knots which are resinous. If untreated the resin is liable to work through. To prevent this two coats of knotting should be given with a half-hour interval. Knotting is usually obtained ready made, but can be made with shellac and methylated spirit. It is really the same as french polish but with rather more shellac. Paint it over the knots with a brush. Really bad resinous knots, however, should be cut out and filled with sound wood.
PRIMING. At least three coats of paint will be needed; priming, undercoat, and gloss coat. All are different, and most manufactures put up the three classes of paint in colours to suit. Thus the priming coat is generally grey, and the undercoat an approximation of the finished colour. Exceptions are in the case of white and the lighter shades when the priming coat also is white. It is always the safe plan to obtain the three paints from the same manufacturer. White lead plus red lead makes a good priming, especially for outdoor work.
All paint must be thoroughly stirred up. If on opening the tin a skin has formed on top, cut around the edge and remove in its entirety. If there is any sign of lumpiness strain through muslin. Choose a flat brush about 2 in. wide, dip about one-third the length of the bristles, and press each side against the side of the tin thus forcing the paint to centre. Apply across the grain with a fair pressure so that the paint is pressed into the grain. The idea is to distribute the paint evenly, and this is helped by working across the grain, then crossing at right angles. In any case finish off with light strokes along the grain.
Allow to dry overnight, then rub down with waterproof glass-paper. This will remove any roughness and give a key for the next coat. Take care not to rub too vigorously at edges or corners or you may rub through to the bare wood.
STOPPING. Putty is often used for filling holes, but a more reliable stopping is a mixture of two parts putty and one of white lead. To make it more workable a little gold size can be added. The same mixture can be used for cracks if quite small. Large ones should be filled with a wood shiver glued in and levelled. Note that a bruise, if shallow, should be levelled with glass-paper; if deep it should be cut in and roughened to afford a grip.
Stopping is used after the priming coat because it may loosen if applied to bare wood. If repairs with wood. If repairs with wood are needed, however, these should be completed before the priming is given.
UNDERCOAT. Except for colours which have exceptional covering powder, the undercoat is of a similar shade to the final gloss coat it dries out flat. Its application is similar to that of the priming coat, and it should stand for twenty-four hours before being rubbed down for the final coat. Use waterproof glass-paper as before. Regulations require that rubbing down should be wet when lead paint in used.
FINAL COAT. In most gloss paints the brush marks flow out, and this means that less working is required. In fact only enough working should be given to ensure an even distribution. Remember that the paint takes on an initial set soon after application, and if working is continued too long the brush marks will fail to run out. The art is in getting on sufficient paint to cover well and give a good body without beginning to run. Do not overload the brush, and work towards the edges; otherwise there will be an accumulation at the corners which it will be difficult to deal with, especially it not noticed at once.
BRUSHES. When required for use the next day these can be kept in water as in Fig. 1. When finished with they should be cleaned out thoroughly with turps and finally washed with soap and water. For fairly wide surfaces - panels, tops, etc. - a flat brush about 2 in. wide is used as A, Fig. 2. Narrow surfaces, mouldings, etc., require the sash tool B. If possible use a new brush for unimportant work for a start, because there are sure to be odd ends of hairs, dust, etc., on it.
Old Work
STRIPPING. The treatment here depends largely upon the condition of the existing paint. Badly cracked or blistered paint is useless as a foundation, and will have to be stripped off. The tradesman invariably uses a blow lamp for this, passing the flame over the surface and immediately scraping off with the scraper as shown in Fig. 3. The softening is very rapid, but care has to be taken not to allow the flame to remain in any one position, because it will otherwise burn. Special care has also to be taken when working near glass. Incidentally, all fittings such as handles, finger plates, etc., should be removed before repainting as it is impossible to get a clean result otherwise.
If a blow lamp is not available it is necessary to use a proprietary liquid stripper. There are many kinds available, and generally it is better to avoid those of a caustic nature because they may affect the paint subsequently applied. If such a stripper is used the surface should be well washed down afterwards, and finally wiped over with vinegar to neutralize any traces of the stripper. Non-caustic strippers are quite safe in this respect, but should be washed off with turps.
Once the paint has been stripped off the repainting is the same as for bare wood. Cracks, etc., should be filled in, and knotting used where necessary. Incidentally, stripping from mouldings is always rather awkward, and a shave hook is generally used by the tradesman (see A, Fig. 3). The pointed end and the rounded end are both used - sometimes it pays to make up a special shape tool to suit a moulding so that the paint is removed cleanly without damaging the wood. In using the hook always well soften the paint with the blow lamp so that no excessive pressure is needed. The latter might damage the wood. After cleaning off, the surface should be rubbed down with coarse glass-paper. For mouldings you can often make a wood block to use as a rubber.
PAINTING OVER OLD PAINT. If the old paint has still a reasonably good surface it can be rubbed down and the new paint applied over it. Use one of the proprietary sugar soaps, such as Manger's, dissolving this in water, the quantity as given in the instructions on the packet. Apply with a brush and scrub over the whole surface. Two buckets are required; one for the sugar soap preparation, and the other for clear water for washing down afterwards. The sugar soap, apart from removing dirt, has a slight abrasive action on the surface which gives the new paint a better grip.
Rubbing down follows, and can be done whilst the surface is still wet, using waterproof glass-paper. The idea is to make the surface perfectly level for the new paint. Some prefer to use pumice stone or one of the special pumice blocks. Waterproof glass-paper is quite satisfactory, however, and is specially useful for mouldings. On plain surfaces it should be held over a cork rubber.
Any necessary stopping is carried out after the first coat of paint. Putty is often used, but a better stopping is made from white lead, gold size, and whiting. It is applied with a knife, and if the latter is drawn across the crack at an angle it will be found that a deposit is left in the crack.
For inside work two coats are generally enough, except when a light paint is to be used on a surface previously dark. These are the undercoating followed by the gloss coat. Any stopping applied after the first coat should be touched up before the final coat is applied. The method of application is much the same as that already described for new wood. In the case of panelling such as a door, do the work in the order shown in Fig. 4, and follow the direction of the grain of the wood. The panels and mouldings are often taken in together. Note specially the order in which the framing is done so that the final strokes of the brush give a clean finish. Thus the short stile (3) is painted first. The brush is bound to go over a little at the ends, but these places are made clean when the brush is drawn horizontally along the rails (4). The ends of the last named are also cleaned up when the long stiles (6) are dealt with. One point of note is that the door edge (5) is painted before the surfaces of the stiles (6). In this way any overrunning at the edge is cleaned off on the surface which is the more important of the two.
WINDOWS. The general preparation of wood frames is much the same as for other woodwork, but in the case of sliding sashes it is as well to remember that the surfaces at the side are liable to thicken with repeated coats of paint, and it will probably be necessary to rub these down, especially in old property. When painting the exterior the simplest plan is to raise the lower sash and lower the upper one so that their positions are partly reversed. As much of the work as can be reached is then painted, after which the sashes are reversed to their normal positions enabling the rest to be completed.
Metal casements suffer from liability to rust. They should be kept well painted. If rust has occurred it must be completely removed as otherwise discolouration is bound to appear. A wire brush is generally the best tool to use. Certain proprietary liquids are available for de-rusting iron, and these are a great help. The difficulty is to keep the metal covered by the liquid, combined with awkwardness of reaching the rust when it is partly covered with a layer of discoloured paint.
To make a really good job it is necessary to use a stripper first. Scrape and scrub with wire brush as soon as the paint is soft, then apply the de-rusting compound. Allow time for it to work, then scrub with a brush. Some compounds form a sort of protective skin on the surface which makes an excellent surface for paint. The usual priming is red lead paste and boiled linseed oil. Sometimes turpentine is added, the proportion being 2 of oil to 1 of turps.
Bituminous paint is often used on iron, but it is essential that the same class of paint if used in subsequent painting as otherwise there may be discolouration and failure to harden out. Another objection is the limited number of shades in which it is available. It is suitable for rain-water pipes, corrugated-iron roofs, and so on. If for any reason it is later necessary to repaint with normal oil paints it is advisable first to give a coat of aluminium paint.
One last word on working in a confined space such as a narrow cupboard or w.c. is that is is generally a help to paint the far wall first. It gives more freedom and saves the accidental touching of the new paint with the arms or clothing.
1 comments:
I find Fig. 4 to be particularly interesting. Also, the hint on how to avoid accidental touching in a closet or W.C., is brilliant.
Post a Comment