—Clearly the first thing to be done before studying the subject of paint and colour mixing is to determine what a paint or what a colour is. Without attempting to give a hard and fast definition, it may be said that a paint consists of any pigment, such as white lead, mixed with linseed oil, and thinned by means of turpentine to render it in such a condition that it may be readily applied to the surface of wood, iron and other work by means of a brush. Paint serves the purpose first of preserving the material to which it is applied, and secondly, but not always, a decorative object where the colour is of importance.

The principal pigment used in paint mixing is white lead, but there are many others that are also employed. Many painters look upon paint as necessarily consisting of white lead to which has been added sufficient colouring matter to give the desired tint. As a matter of fact, white lead may be wholly absent from a paint. For example, yellow ochre may be used by itself; iron oxide in the shape of Indian red, purple brown, Venetian red, or Tuscan red forms in itself a good paint if the colour is not objectionable. Again, in the lighter paints we sometimes have white lead replaced by an admixture of zinc white, barytes and other materials of the kind.

The oil used in mixing paint is used to combine the particles or pigment together. That is its chief object, but it is also employed to give a glossy surface and to bring the material to a proper consistency. Turpentine could be used for the latter purpose by itself, but the result would be what is termed a “flat” surface, or an absence of gloss. The turpentine, too, evaporates to a considerable extent. It is generally conceded, among those who have given close attention to the subject, that the durability of a paint depends largely upon the oil used; indeed, it has been likened to the life-blood of the paint. There is not much doubt that the best pigments may be replaced with others somewhat inferior without so much detriment to the quality of the paint as if linseed oil is replaced by some other oil. It is quite necessary that pure linseed oil be used in the manufacture of all paints, and although there are one or two substitutes on the market which may be employed in very cheap work, no attempt should be made to execute a really good job unless pure linseed oil is used. The purpose of the oil in giving a gloss is sometimes assisted by the addition of a small quantity of oak varnish. This is a growing custom among painters, as the gloss produced is decidedly improved by the addition of the varnish and the work shows up well, while the varnish does not in any way detract from the life of the paint, but rather adds to it. This practice is employed more on inside than outside work, where the execution of the painting requires more care than it does inside, owing to the severe atmospheric conditions, which cause any paint work not properly prepared to soon decay.

The base, such as white lead, having been selected, colours are mixed in order to produce the desired hue or tint. Frequently, however, a colour is made by the mixture of several other colours without any white lead at all. A careful examination of the list included in this book will make this clear.

The colour having been determined, oil, turpentine, and driers are then added. The object of the driers is that of causing the paint material to dry quickly. There are several kinds of driers on the market, but the two best known are termed “patent driers,” which is sold in solid form, and the “liquid driers” or “japanners.” Whichever is used the actual quantity employed will depend very largely upon the pigment. Some pigments, say for instance, red lead may be considered in itself a drier, and the addition of any other is unnecessary. Others, like Vandyke brown, dry slowly, and much more driers will be necessary than is the case with white lead. Further on we give some idea of the proportions of materials to be used, but it will be understood that no exact information on the subject will be possible, for reasons that will be explained. It is of the utmost importance to remember that an excess of driers is most objectionable. It often retards instead of increasing the drying quality, it causes cracks and blisters, and above all, it proves very destructive to the paint itself.

The quality of patent driers varies very greatly, some of the cheaper grades consisting largely of material which possesses no drying properties whatever.

Paint Mixing.

—The method of mixing paint does not appear, strange as it may seem, to have received the consideration on the part of practical painters that it deserves. While the manner of mixing small quantities of paint is thoroughly practical and sensible, yet some painters, even when they have larger quantities of the same paint to mix, adopt exactly the same means without thinking it necessary to take advantage of special machinery which is made for the purpose.

There are on the market two sorts of mixing machine for paints that would prove of great service to the painter who has to produce large quantities of paint. But, as a rule, they are only used by paint manufacturers. One known as the vertical mixer, is represented in Fig. 1, and is suitable for painters’ use. It consists of a cylinder which contains the paint, and in this are three bent knives or scissors. The handle attached, on being operated, turns the cylinder in one direction and the knives in the opposite direction, these knives in the meantime revolving around on their own axes. The paint is thus mixed very quickly, and as the cylinder may be had to hold several gallons, in the case of bridge work, wall work, or other positions where a very large quantity of the same paint is required, the purchase, for a few pounds, of such a machine may mean a saving of a considerable amount of labour. The mixer illustrated is manufactured by Messrs. Torrance & Sons, of Bittern, Glos. In many shops, where large quantities of stone colour and other paints have to be turned out, such a machine would soon repay its cost.

For ordinary quantities of paint, of which white lead forms the base, the following is the method usually employed. It will be understood that the paint consists of a base such as white lead, linseed oil, either raw or boiled, driers—either patent or liquid—and turpentine. A can or kettle is most usually employed for mixing the white lead in, and this is first thinned out and mixed with the driers and oil, the colour being afterwards added to it. A little oil is first placed in the can, which is twisted around so that the oil covers every part of the inside surface. This prevents the lead sticking against the tin. A sufficient quantity of oil and the patent or other driers is then added. The most convenient implement for actually mixing the paint is a broad piece of wood shaped like a narrow spade, or a spatula may be employed. The lead is stirred and beaten against the sides of the tin until the whole is of the same consistency, and more oil is added until the thickness is not sufficient to support the stick standing upright. Turpentine may now be added to further thin the mixture, and then the colour is added. It may be noted here that the result is not so satisfactory if the turpentine is added before the oil. The best way of mixing actual colours is to place them on a stone, thoroughly amalgamating one with the other by means of a spatula. When the colour is what is required it is added to the white. To take a simple case of a gray, a little black would be beaten up on the stone, and when quite thin added to the pot of white. This would then be stirred up thoroughly and the grey colour observed to see whether it was sufficiently dark. Then a very little red and blue might be prepared on the stone and this be added to the pot, the mixture being again stirred. Two very important rules must be observed at this point. The first is that the colours ground in oil should be used and not dry colours. If dry colours are employed oil must be added to them on the stone and not in the pot. We may repeat, by way of emphasis, under no circumstances must dry colours be added to the pot of colour. This is a rule to which there is absolutely no exception. The second rule, and one which is equally important, is to add only a small quantity of colour to the pot of white at the time. Taking the case once more of the grey, a little black being added and the mixture well stirred it can be seen at a glance whether the desired depth of shade is obtained. On the other hand, it would be quite impossible to take any of the black from the mixture, and should it be too dark the only way to lighten it would be to add more white, and this would probably mean mixing much more paint than was required for the job.

The paint having been mixed to the exact colour required, all that now remains is to strain it. A piece of muslin is often used for this purpose, but a far better method is to use a wire gauze strainer, which may be purchased for a small sum and will last for a considerable length of time. The advantage of this in addition to its permanence is that the hard portions of the paint may be beaten against the gauze, and so the waste be reduced to a minimum.

An excellent shape of paint strainer is that shown in Fig. 2, which is shown in parts in Fig. 3. A, represents the body of the strainer, B, the clips which hold the compression band C, and D, represents the gauze. The advantage of this construction is that the gauze after use may be easily taken out, cleaned and replaced. This strainer or its equivalent should form part of the equipment of every paint shop, large or small.

A very handy little tool for breaking up oil paint when mixing in a can instead of using a stick is shown in Fig. 4 (see next page). Its shape enables it to be used also as a scoop or spoon for lifting the colour out of the kegs, etc. The patentee and manufacturer is H. Smith, Hale Road Bridge, Altrincham, Cheshire. The illustration shows both sides of the tool. The projection on the left hand of the carved blade is provided in order to reach beneath the rim of lever-top cans.

The Proportions of Materials.

—We come to a consideration of the proper proportions of materials, viz., white lead (or other white), oil, turpentine and driers—the colour we shall speak about shortly—to be used on various kinds of work.

A little consideration will make it quite clear that it is impossible to give exact proportions of materials that will suit every job. These proportions are determined by the condition of the work. A new door of good sound pine will be treated differently to one made of an inferior wood, which is knotty and somewhat sappy. Again, a door that has been exposed to the weather for some years, and from which the paint has, perhaps, almost wholly departed, will require a different mixture to a front door from which the accumulation of old paint, extending, perhaps, to over one hundred years, has been burnt off. Precisely in the same way as patent medicines cannot be safely used for any and every complaint, so it is impossible to have paints that will suit any and every purpose. In one case the doctor is consulted and he takes into consideration every symptom and every condition and acts upon his diagnosis or scrutiny of symptoms. In like manner the decorator takes note of every condition of his work, and prepares his paint accordingly. Again, iron would not be painted with the same mixture as wood. Still if we cannot give exact proportions, we can, at least, give some information on the subject, which will form a guide and give some data for the reader to work upon. These we will give under separate heads.

Priming for Iron.

—The usual plan is to use red lead mixed with linseed oil, the proportion required being about 14lbs. of linseed oil to every cwt. of lead. The second coat should be equal proportions of red and white lead mixed to a proper consistency with linseed oil. Sometimes oxide of iron paint is used instead of red lead.

Painting on Stucco.

—The priming must contain a considerable quantity of oil, because of the absorbent nature of the stucco, and it should have a big proportion also of turpentine. Four galls. of boiled oil to a cwt. of red lead and three quarts of turpentine will usually answer. The second coat should be an equal mixture of red and white lead with a smaller proportion of turpentine and oil.

Priming for Deal or Pine (inside).

—With white lead use three-quarter ounces of driers and the same quantity of red lead to every pound of lead. Thin with about the same proportion of turps and raw linseed oil.

Second Coat (inside).

—Use about half-an-ounce of driers and one ounce of red lead to every pound of white lead.

Second Coat (outside).

—Use about one ounce of patent driers to every pound of white lead, with the addition of about the same quantity of red lead.

Egg Shell Gloss.

—To every pound of white lead add quarter of an ounce of copal varnish and the same quantity of gold size with half the quantity of boiled oil. These will serve the purpose of binding the materials together and causing them to dry. The thinners should consist of turpentine used in the proportion of about three-quarters of a pint to every 7 lbs. of white lead.