Preparation and Painting of various surfaces

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PREPARING AND PAINTING VARIOUS SURFACES.

A working acquaintance with the nature and peculiarities of every painting ground is a necessary equipment of the jobbing builder. All painting work must possess at least a reasonable measure of durability. It is no excuse when painting work goes wrong in six months' time to blame the ground. The painter's business is to know how to deal successfully with every ground, and produce a lasting surface.
There is no royal road to success in this direction. There is no one certain cure-all. There is no one paint suitable for every painted ground. It is just here where the jobbing builder is likely either to lose or make money.
Almost every building surface comes at one time or another within the scope of the paint brush-wood, iron, galvanized iron, steel, tin, lead, aluminium, zinc, compo board, asbestos sheeting, and rendered surfaces as plaster, cement, and rough cast. The conditions under which these materials are encountered have also to be considered-whether they are new or weathered, painted or unpainted, sheltered or exposed.
If success is to be achieved, the foundation must be laid in the first or priming coat. Otherwise subsequent coats will eventually blister or scale.
A review of the many and varied surfaces the painter has to deal with is sufficient to convince even the least observant that no one paint, or at least no one mixing, is suitable for all.
Priming and Knotting.
For paint to dry without blistering, the woodwork must be dry. In this speculative building age that is asking for the ideal. Woodwork is seldom if ever bone dry. Worse still, in housing and speculative building, the bare wood often remains unprimed for weeks, a prey to atmospheric conditions.
It is a practice with some to prime with water paint because it covers well-a practice that should be avoided, at least for exterior work.
Knotting, a simple operation, occupying at most only a few minutes, is often scamped or conveniently forgotten, and in a few weeks' time it is possible to count correctly the number of knots in a building.
The wise builder will never allow knotting to be omitted from his system of painting, even though some so-called experts may aver that it is unnecessary when the priming coat is a water paint; rather he will go over it a second time.
Scrap the semi-airtight vessels that pass for knotting bottles, and throwaway the blackened mess often passing for knotting, which, when applied, cannot be hidden under a dozen coats of paint, and use clean pale thin knotting in clear airtight cans. Pale knotting is the painter's best friend. With it backward parts can be quickly brought forward and troublesome surfaces made amenabie to the paint brush. It has, in fact, a hundred and one uses to the experienced, being among others a good carrier of aluminium and bronze powder. Almost as useful is a supply of methylated spirit, so that when large brushes ate temporarily used in knotting they may be washed out right away. Have a bottle for the spirit so used, which will always come in handy.
For deal or pine there is no priming better than a lead paint. A good mixing will include sufficient dry red lead to give the paint a faint pink tinge. A suitable mixing would be paste white lead, ½oz. patent driers to each pound of paste lead, ½ oz. dry red lead, linseed oil 2 parts, turpentine 1 part. Priming should be used on the thin side in order that it may penetrate the wood. For wood slightly damp a good turps substitute may take the place of the turpentine altogether or in part. Rule out, however, common paraffin, or poorly distilled petroleum, the greasy nature being inimical to painting permanence.
Hard woods require less oil in the priming coat, and the mixing may well be in the proportion of turpentine 3 parts, linseed oil 2 parts. Boiled oil should be strictly ruled out of all priming and undercoats.
A fair description for ordinary deal grounds should include all likely eventualities. Twice coat all knots with pure shellac knotting. If on front doors, undercut any knots that may be prominent and fill up or replace with clean wood. Sappy parts should be treated with knotting diluted with methylated spirit, otherwise the paint on these parts will sink and leave a dead surface.
It is advisable to do all stopping on the priming coat, and for good work use a stopping made from equal parts by bulk of good linseed oil putty and paste white lead. Some of the common putty would not be hard in ten years except on the surface. Good linseed oil putty dries throughout, common fish oil on surface only.
The second coat may be mixed, linseed oil 1 part, turpentine 2 parts.,
The third coat may be mixed, linseed oil 2 parts, turpentine 1 part.
The fourth coat may be mixed, linseed oil 4 parts, turpentine 1 part.
If, however, gloss enamel is to follow the third coat, the third coat should be mixed with linseed oil 1 part, and turpentine 3 parts, and the same mixing will do for a clear varnish finish or for a varnish paint.
Driers.
There is always the question of driers to be considered. After the priming coat 1 oz. of paste drier may be allowed for each pound of pigment. The up-to-date builder will always purchase driers from the same firm and make careful tests on trial boards. Much is to be said for liquid driers under the head of convenience, and tests should be made on lines similar to those with paste drier. Knowledge of the capabilities of the driers used will suggest addition during cold or damp weather, and a less quantity during hot dry weather. It is not a question so much of economy in driers as lengthening the active life of the paint. A point made by the manufacturers of ready-mixed paint is that the proportion of driers is always the same. Has it ever occurred to the builder that a pair of scales and a pint pot would be welcome to the foreman painter? The jobbing builder may object on the score of time economy to mixing paint. For all ordinary painting only the glossy need be purchased. Take any well-known brand of glossy white lead paint. For the first coat pour off the liquid without stirring, and thin with turpentine. Second coat:. use top liquid and turpentine in equal parts. Third coat: use top liquid 2 parts, turpentine 1 part. Fourth coat: use the glossy paint alone.
For an enamel finish, where it is inconvenient to stock both flat and gloss white lead for the ground previous to enamel, drain off the top liquid and thin with turpentine alone. The addition of a small proportion of liquid drters under some weather conditions should be considered.
Fillers for New Woodwork.
New woodwork of good class often requires filling up or surfacing. Here much time may be lost and money wasted. House painters, unlike coach painters, do not as a rule excel in filling painted surfaces. Most foremen have their own pet formula. An enamel filler in white or grey, as supplied by some paint manufacturers, is advisable. This may be used with the broad knife or applied with the paint brush, and will rub down safely and easily.
A ready home-made filler, suitable for most purposes, is equal parts by weight of paste white lead, white lead in turps, powdered whiting in turps, doing whatever thinning is required with qwck japanner's gold size. This, after being strained twice through a fine wire strainer, may be used with the broad knife and promptly cleaned up with turpentine. Bad parts may require a second and even a third application. When dry rub down with glass-paper, wet or dry, or with pumice stone and water. When filling is applied it should come on the second coat.
Other fillers favoured are good-class water paints stiffened with powdered whiting, Keene's cement, or plaster of Paris. In every case the surface should be left knife clean, and very little dependence placed on subsequent rubbing down.
Painting Metal.
Iron gutters and stack-pipes are often primed with oxide of iron paint. Equal quantities of red oxide and red lead would be much better. Red lead paint, owing to its powers of oxidation, should be mixed as required. It soon thickens and becomes unusable. Turpentine is often added in excess, detracting from the value of the paint.
All wrought iron should be primed with red lead, or red lead and vegetable black, according to finishing colour, as soon as possible after fashioning. The same paint may be used for steel.
Sheet tin requires painting to prevent rust. Whatever the pigment, the priming coat should be equal parts linseed oil and turpentine plus driers, and each succeeding coat should be more elastic than its predecessor, that is, more oil should be incorporated.
Galvanized iron is often the builder's bugbear. Many solutions have been suggested. The chief difficulty is the smoothness of the surface and possibly its greasiness. Galvanized iron always paints easier and with more likelihood of success after several months' atmospheric exposure. Wash the surface with a solution of soda, 1 lb. to a gallon of hot water, and rinse off with clean water. Another easy method is to use coarse glass-paper or emery cloth.
Where colour is not an objection, one of the bituminous paints ranging from brick red to dull green would be advisable. Possibly success would be more likely than with an oxide paint.
Sheet lead and lead pipes are generally painted for appearance's sake only. An oily paint is always to be preferred, as sharp flat paint cracks and falls away after a time.
Sheet aluminium is troublesome. It quickly oxidizes and has a stubborn greasy film. It should be cleaned with petrol, and at the same time rubbed with fine glass-paper. It may be followed with a coat of japan gold size and turpentine, most of which may be wiped off again, simply leaving a sufficjent coating to leave the surface unexposed. Afterwards each succeeding coat should be more elastic than the one before it. Zinc, owing to its smooth surface, is difficult to paint. It may be treated with any of the well-known hydrochloric acid washes, though simple rubbing with glass-paper and turpentine, rubbing in one direction only, is all that is generally required. The priming coat should be mixed with equal parts oil and turps; afterwards any treatment may follow.
Painting Asbestos.
Asbestos sheeting presents a real difficulty to the jobbing builder. Seldom is painting on this material a success. Water paints have been suggested with or without their accompanying petrifying liquids. Success is claimed with various proprietary liquids. Possibly much depends on whether the sheeting has weathered or is comparatively new. The delinquent is evidently the cement incorporated.
Whatever preventive measures are taken must be used previous to painting. A wash over with vinegar alone is sometimes suffident. Weak acetic acid will answer. Another likely treatment is to coat twice with sulphate of zinc, using a solution at the rate of 5 lbs. to the gallon of water. Paint without washing off the sulphate.
The paint that follows, especially the first coat, should contain very little oil. If the jobbing builder could make it, the ideal paint would probably be one composed of pigment, a Tung oil-rosin varnish, and paraffin. Such a paint gives very little scope for enclosed alkali to work on.
Failing a paint of this sort, the next best would probably be pigment mixed in japan gold size 1 part, turpentine substitute 2 parts. On this let each following coat contain as little oil as possible. In fact, it would be an advantage to leave oil. out of the paint, using instead a copal varnish or, for common work, a cheap gloss varnish.
Painting Cement.
Portland cement, whenever possible, is left at least six months before painting with oil paint is attempted. There are exceptions where repairs are done on compo fronts, and for some unknown reason the painter often coats with red lead and oil. Repairs of this sort are better washed with acetic acid and coated with a paint mixed in gold size and turps.
If Portland cement surfaces must be coloured, the easiest method is to use an ordinary size distemper, which may eventually be washed off. Water paints and petrifying liquids are not usually a success.
Painting Plaster.
Plaster also paints best when weathered, and should not be painted for at least six months. Even the water paint should be selected with care, or the surface will dry out unevenly.
Plaster that is to be finished in paint is sometimes given a coat of glue size to stop suction and save paint. A much better priming is varnish ~ parts, turpentine 1 part, adding sufficient white lead to give a key for succeeding coats of paint.
Keene's cement, whether small repairs or large surfaces, and whether to be painted, distempered, or papered, should be painted with thin white paint as soon as the surface will bear the brush. If left untouched, whatever follows later, paint or paper, will not remain on for any length of time.
Sirapite may be treated after the manner of Keene's cement, but whether this is always necessary is a debatable question.
Repairs done with Parian cement are generally safe under all conditions and without treatment.
Plaster of Paris is a good friend for many purposes, but wherever oil or varnish paint is to follow, Keene's or Parian is to be preferred.
Concrete and rough-cast surfaces often look best left alone. A freshly made lime into which boiled oil or tallow or other binder is incorporated gives a good and cheap finish, but the lime must not be dead. Water paints of outside quality may be used, or the special paints, but the absorbent nature of rough cast often makes their use prohibitive.
Pipes and Radiators.
Hot-water pipes are best coated with an oily paint. If dark colour is used, boiled oil is better than raw. Sharp paint on hot pipes usually scales. As a primer, aluminium paint is to be preferred, and if the cold appearance is not objected to, makes a good finish.
Radiators, whatever may be their finish, may be primed with aluminium paint. If, however, a copper or old bronze finish is. desired, these paints will naturally be preferred.
Gold bronze paints are best bought with a guarantee as to their colour permanence. Aluminium paint for most purposes, however, may be made by adding dry aluminium powder at the rate of from 3 to 5 lbs. of powder to a gallon of liquid made from medium-grade varnish 7 pints, turpentine 1 pint.