Oil paint

“ To mix 1 pound of ordinary oil paint, take about 8 ounces of pigment the desired color. White lead for white, light grays, pinks, cream, etc., Venetian red or vermilion for red, and so on, according to the color desired. Add to this about 2 ounces of liquid driers, then make up to 1 pound with either linseed oil alone or oil and turpentine in equal parts. Remember, the more oil, the more driers is advisable, but never less than 1 part driers in 8 or 10 of entire bulk. If only small quantities of paint are wanted, that sold ready mixed would be cheapest and would do for ordinary inside work. ”

“ To a certain extent the size stops the absorbent powers of the wood or plaster, but it prevents the proper adhesion of the oil paint, which soon cracks or peels off. It may, however, be used with advantage in old work, where the grease would prevent the proper drying of the oil paint, but even in such cases it is best, when possible, to scrape the wood or plaster until a new surface is reached, on which the oil paint may be successfully applied. ”

“ Cheap paint should not be used for inside work any more than on the exterior of the building, if good results are to be expected. It is a mistake to use cheap ochre for priming. The same paint, or something as good, should be used for priming or first coat as is used for the finishing coats or for building up the ground work for enameling, graining and like work.
Oil Paint in White. Where two coat oil paint work is specified, without sizing, the first coat should be reduced with half turpentine and half oil to a good consistency, then a half pint of good hard drying or enamel varnish added. ”

“ In oil painting you cannot do it so well except you paint over large parts, because the colours in drying acquire a yellower hue, than they have while fresh; there will always [Pg 68] be a difference between the very same tints; besides, oil pictures are frequently greasy-like and refuse the new colours, so that you are obliged to rub those parts with oil, to make the new colours adhere to and flow over the old ones, which rubbing with oil very often makes a dull and yellow spot when the colours are dry ”

“ In the language of another, "Raw linseed oil is the king of the paint realm. There are lots of usurpers in the field but they are short lived. The true homage of the brotherhood of the brush continues to be paid to the old stand-by. It is the gold of the paint shop currency."
In the basic stage of carriage and wagon painting, pure raw linseed oil is conceded to be the life of the pigment. Impure or adulterated linseed oil—the spurious, fraudulent article, if you please—has more to do with the premature decay of paint and varnish than one at first thought might concede. ”

“ Where an excess of boiled oil has been used in successive repainting and the work has commenced to crack or alligator, it will be found very hard to get the work in good condition, as the oil will set on the surface and form a glaze which is very hard to penetrate; likewise where fatty oil or paint with a percentage of gloss or rosin oil has been used. While the heat of the burning lamp softens the oil and paint, it is very hard to remove all of it from the surface. ”

“ When oil-boilers were compelled to adopt some expedient to give a reddish-brown colour to the oil, they added a small amount of litharge, the introduction of which actually spoils the oil, and makes it unsuitable for many purposes to which it is otherwise applicable. Of late years, pale boiled oils have been more largely manufactured for special purposes. It is obvious that, for decorative house painting, in which delicate tints are a leading feature, they may be advantageously employed. ”

“ To repaint a job which has commenced to scale, without taking off all the old paint, is very uncertain work, but if you have to try it, have it understood in writing, or before witnesses, that it is done at the owner’s risk. First scrape off the loose paint, then go over the job with raw oil; put it on freely and let it stand until dry; then scrape off all the paint loosened by the oil, and coat up with strictly pure white lead and oil. Avoid zinc, and mixtures of zinc, and barytes, on jobs of this kind; because they are more or less liable to crack, and pull off more of the old paint. ”

“ When mixed with linseed oil paints the odor of menhaden oil is sometimes noticeable, but it disappears entirely after such paints are applied. Its use with linseed oil in technical paints exposed to the salty air of the Coast has given good results, often preventing “checking” and “chalking.”
The following constants were determined on samples of menhaden oil received in the writer’s laboratory:
Whale Oil. ”

“ To avoid peeling and blistering, the paint should be mixed with raw linseed oil in such proportions that it neither becomes too brittle nor too soft when dry. Priming paint with nearly all oil and hardly any pigment is the foundation of many evils in painting; it leaves too much free oil in the paint, forming a soft undercoat. For durable painting, paint should be mixed with as much of a base pigment as it can possibly be spread with a brush, giving a thin coat and forming a chemical combination called soap. ”

“ If the surface has been previously painted and is in good condition, thoroughly sandpaper and apply a coat of paint mixed fiat and tinted to the proper ground color with a pint of hard-drying varnish added. Should the paint dry too flat for good working or combing of the graining color, an additional amount of varnish can be added, or a small amount of oil. If numerous coats of oil paint have been applied, or if the surface is badly cracked, the paint will have to be burned or removed with paint remover, then proceed as with new work. ”

“ Although several grades of oil termed crude, brown, light, etc., are produced, the most satisfactory for use in paint is that grade termed “light winter pressed.” This oil is of a pale straw color and has a high iodine number which is responsible for its rapid drying value. It contains less of the stearates that precipitate from crude oil, but sufficient to render its film water-shedding and elastic. The presence of too great a quantity of stearates is apt to result in a [14] very soft film, and the use of hard driers, such as the metallic tungates, is therefore advisable with menhaden oil. ”

“ These oils when mixed with drying oils and strong driers find application in the manufacture of some freight-car, barn, and other paints which sell at a low price. A small percentage of mineral oil is said to be valuable in structural steel paints, acting as a preventative of hard drying and thus keeping the film soft and elastic. Streaking and sweating is apt to ensue if any great quantity is used. ”

“ It is well known that one of the most desirable features of a paint oil is the ability to set up in a short period to a hard surface that will not take dust. This drying property is dependent upon the chemical nature of the oil. If it is an unsaturated compound, like linseed oil, rapid absorption of oxygen will cause the film to dry rapidly and become hard. If the oil be of a fully satisfied nature, like mineral oil, oxygen cannot be taken up to any great extent and drying will not take place. ”

“ Treatment with steam and alkali serve to neutralize the acid nature of the oils and to remove impurities. Refined oils are lighter in color and are often blown and bodied to fairly rapid drying products, especially when treated with manganese driers. Rosin oils are seldom used with lead pigments, on account of the presence of sulphur in the oils, which would result in darkening. Rosin oil paints work very smoothly, even when they are curdled, producing glossy surfaces. The rapid checking of rosin oil paints on wooden surfaces bars the use of this oil for such purposes. ”

“ Ochre or similar slow-drying pigments mixed with boiled oil will very often be found at the bottom of this trouble. Fatty paint or the use of adulterated oil also causes paint to alligator. Such paint is usually tough and hard except where it is well protected and there the undercoats will be found to be tacky and spongy. The only successful way to repaint this surface is to burn off the paint. This is a very difficult job, as the heat softens up the excess of oil and a gummy, sticky mass of paint is the result. ”

“ A vehicle is any liquid which is mixed with the color to make it fluent. The vehicle may be ground with the pigment or mixed with it on the palette, or both. Oil colors are of course ground in oil as a vehicle; but it is often necessary or convenient to add to them, in working, such a vehicle as will thin them, or make them dry better. Those which thin or render more fluent the paint are oils and spirits; those which make them dry more quickly are "dryers" or "siccatives."
All vehicles must of necessity have an effect on the permanency of the pigments. Bad vehicles tend to deteriorate them ”

“ The careful painter will, when using heavy pigments, carry a paddle, and not neglect to use it. To prevent white lead and other heavy pigments from settling in the pot the paint must be well mixed, and kept mixed by stirring with a paddle as often and as much as may be necessary to keep the oil or other vehicle, and the pigment well incorporated. No one out a novice, or a careless painter will permit a sediment to accumulate in the bottom of his pot; no matter whether the pigment is coarse or fine; or whether the vehicle used is linseed oil, turpentine or benzine. ”

“ A simple method of obtaining an approximate result is to procure a sample of oil of known good quality, and to colour it with an aniline dye. A drop of this tinted oil will, when placed in the oil to be tested, indicate, by its sinking or swimming, the relative density of the liquid under examination. Freshly-extracted linseed oil is unfit for making paint. It contains water and organic impurities, respecting the composition of which little is known, and which are generally termed “mucilage.” ”

“ Dry colors mixed by hand should never be used for priming. All paint pigments are much more bulky in the dry state than when properly handled under pressure and combined with oil. When a mixture is made without pressure the outside particles of the pigment are only coated with the oil or thinners, and when applied to a surface, the wood having a greater attraction for the oil than does the pigment, the surface will absorb the oil from the pigment, leaving a dry, porous coating to which subsequent coats cannot successfully bind. ”

“ The presence of oxygen is not necessary for this decomposition; but it is increased by the action of light. Raw linseed-oil dries more slowly than boiled; but the resulting film is more brilliant and durable. Raw and boiled oil are therefore usually mixed in proportions varying according to the time which can be allowed for the paint to dry, or to the properties required of the film. For the ordinary kinds of paint, equal parts of boiled and raw oils are customary. Linseed-oil heated to a temperature of 350°-400° F. dries much more rapidly than in its raw state. ”

“ The paint for a job stands mixed over night; the painters fill their pots from time to time during the day, but never stir the paint from the bottom, hence the last pot or two filled will have all the coarse pigment of the batch. There are cases, I admit (too many of them) , where not only white lead, but dry colors and colors in oil, are too coarse to work well, but the best white lead and heavy colored pigments in oil or turpentine are liable to be called sandy unless frequently stirred by the painter. ”

“ Where dry ochre or similar primer has been used, causing the paint to peel from its not having penetrated the surface, only a small proportion of oil having gone into the wood, it is very easy to remove with a burning lamp, leaving a surface which is practically new, as most of the oil will have been drawn from the wood during the process of burning. This surface can then be treated the same as any new wood, with possibly the exception of some protected parts where the oil has penetrated to a greater depth and the paint is in better condition than on exposed parts. ”

“ Linseed oil has the power of drying when spread out in a thin layer, becoming of a resinous consistence like varnish, and upon this quality depends the drying powers of paint, for the other non-drying oils, as olive oil, may be exposed to the air for months without drying at all; the drying powers of linseed oil are greatly increased by boiling it with litharge (oxide of lead) . This forms the drying or boiled oil used in painting, and is employed in making varnishes, printers’ ink, and for other purposes. ”

“ By consulting experienced and unbiased painters you will learn the fact that there is no vehicle pigments at all approaching linseed oil in effectiveness and durability, especially for exposure to the weather. A good paint must be both hard and elastic. It requires hardness to prevent abrasion and wear, and elasticity to prevent cracking from expansion and contraction. Nothing but linseed oil will give these qualities, for, strange as it may seem to many in these days of novelties, the pigments really add but very little to the effectiveness of paints. ”

“ The essences of turpentine and of petroleum may be used to thin the paint, and are preferable to oil, because they have less darkening tendency. They do not, however, bind the color so well, and the paint should not be put on too thinly with them. Usually there is enough oil ground with the pigment as it comes in the tubes to overcome any probability of the paint scaling or rubbing when thinned with turpentine, but in the slow-drying, transparent colors there will be a liability to crack. ”