CHAPTER XIV.
A STUDY OF MATERIALS: WHITE LEAD, ITS PURITY, ETC.--QUALITY OF COLORS IN GENERAL--ADULTERATION PRACTICALLY CONSIDERED--PURITY OF RAW LINSEED OIL--TURPENTINE--TESTING COACH JAPAN--VARNISH.
The name of a thing should not be accepted for all there is to the thing itself. The carriage painter has very pronounced reasons for bearing this fact in mind when engaged in studying and passing judgment upon the materials he finds it needful to use in his business. Probably the most important pigment which finds its way into the carriage and wagon paint shop is white lead. This pigment has afforded a theme for increasing discussion, its qualities and adaptability having been extensively canvassed. Numerous substitutes have been introduced during the past two decades, but white lead still retains its pre-eminent popularity. Lead compounds and various adulterated brands have given the painter plenty of trouble, and caused him to devote more attention to the quality of his white lead stock than formerly. Because of its soft, pliable, grain-filling property, its established elasticity, density, body, fine working quality, and its merits as a reliable drying pigment, white lead is the filling up and foundation material _par excellence_.
The purity of lead deserves the carriage painter's first consideration. It has been practically determined that a pure lead, endowed with all the virtues which should distinguish pure lead, when mixed and used in combination with other pigments or colors, holds its quality better and is less susceptible of change than a compound or adulterated lead. Moreover, pure white lead, with its soft, fine, elastic texture, has a natural adhesiveness, a surface-filling and leveling-up property, which the impure lead carrying a percentage of gritty, flinty ingredients does not possess. The pure lead works out under the brush more pleasantly and with less brushing than the compound, and it dries with greater uniformity, etc.
At the same time it is well to remember that a strictly pure lead may have a number of features in its make-up decidedly objectionable to the carriage painter. It may be imperfectly washed, or it may be too coarsely ground, etc. In his study of white lead, then, the painter will find it a matter of value to determine the adaptability of the lead to the requirements of his business. After convincing himself of the purity of the lead, it remains for him to test for fineness of grinding. A lead ground fine--impalpably fine, if it please my readers--lightens the labor of sandpapering, strikes into the wood fibres stoutly, and covers the maximum surface space. It has good coloring and covering power when mixed with colors to form tints, and for other important parts which a white lead plays in vehicle painting it is especially adapted.
Nor should a carriage lead be ground in too large a percentage of oil. For coats between priming and color but comparatively little oil is needed, and washing out with benzine or turpentine entails an unnecessary amount of labor. Hence, it should be insisted upon that carriage painters' lead be ground moderately stiff in oil, so that protracted washing-out may be avoided on the one hand, and extended mixing and breaking-up operations shunned on the other. A practical and, at the same time, a conclusive test of fineness is furnished by taking two pieces of plate glass 8×8 inches in size, setting them securely in blocks of wood, and then smearing a couple of small flakes of the lead, rubbing the pieces of glass together. Continue rubbing with a firm, even pressure until a uniform distribution of the pigment and a thorough impact is established. The glasses should then disclose the nature of the grinding. To learn the drying power of the lead, take the palette knife and slick a small quantity over the glass and set aside, noting the time consumed in drying. A lead ground in the proper proportion of oil for carriage work should, as taken from the keg and smeared in a thin film over the glass, dry in twelve hours so that the finger may be passed over it without sticking.
What has here been said in reference to chemical purity or strictly pure as a necessity in the white lead product does not apply to all the pigments so useful to the vehicle painter. For reasons here shown lead extenders and lead compounds should be emphatically objected to. A disavowal of their worth as carriage painting pigments, however, in no wise lessens the significance of the fact, as already pointed out, that a strictly pure lead is very often an expensive, if, indeed, it be not a worthless, lead to buy. Chemically pure is not invariably an accurate gauge of quality. A chemically pure lead that has not fineness to recommend it lacks an essentially vital quality. In respect to the pigments and colors following in the wake of white lead it has been made plain on many a hard-fought field of experiment that the color consumer, the practical painter, the workman far removed from the analytic gentleman of the laboratories, is chiefly concerned in getting a pigment or color adapted to his needs more completely than any other available one. It may not be chemically pure as the chemists would construe the term; but if it responds satisfactorily to a practical test, it is then serving the painter's practical need. As declared by the writer, in an article published some time ago, "a color or pigment may be pure in the sense that it is not adulterated, and still fall short of being chemically pure. It is the duty of the consumer to avoid buying, under the label 'strictly pure,' an adulterated color. The real color contained in such a product is then costing him considerably more than would a color in a state of purity." The chemist and the practical painter do not agree oftentimes upon what may be called adulterants. Once upon a time, as the fairy books say, at a painters' convention the chemist employed to make an analysis of chrome yellow stated in substance that practically everything outside of the chromate of lead should be classed as an adulterant or as a matter out of place. The practical painter who has looked up the subject of chrome yellow manufacture could tell the chemist in this case that he has signally failed to take into consideration the necessary constituents of the different shades of chrome yellow. As, for example, acetate and nitrate of lead, bichromate of potash and bichromate of soda, sulphate of soda, etc., are constituents of a pure chromate of lead. And our friend, the chemist, would tell us that a chromate of lead composed of some of the above ingredients is not a chemically pure article. What the carriage painter, the consumer, will find it of value to ask himself is this: Does a given pigment or color suit the requirements of my business? If in doubt as to the utility of the given pigment or color, then an immediate practical test should be resorted to. It is not the purpose of the writer to belittle the position or the usefulness of the chemist. The value of a chemical analysis in the detection of adulteration and in explaining how a color is made is cheerfully acknowledged; but after the chemist's deduction must follow the practical test. In conducting a practical test the foremost aim of the painter should be to consider the color or pigment to be tested in relation to the object for which it is intended. Shade, brilliancy, working property, durability, etc., are entitled to a careful and chief consideration in a test for quality. And a test for quality, if conducted painstakingly and thoroughly, will disclose the real value of the material to the consumer. When extenders are added to a pigment for the sole purpose of enriching the manufacturer at the expense of the consumer, the practice becomes adulteration, pure and simple. If, however, such extenders are used to, and actually do, increase a pigment's usefulness, fortifying it in a way and to an extent that it needs to be fortified, the painter will not attempt to question its commercial value.
The study of the pigments which the vehicle painter calls to his uses is a feature of business deserving the most rigid attention. Carried on watchfully and with a vigilant regard for details, it cannot well fail to increase paint shop profits.
LIQUID MATERIALS.
In the consumption of liquid materials the vehicle painter has no use for extenders. Unfortunately, however, the thrifty and shifty sons of adulteration, after the manner of Marco Bozzaris, in the Fourth Reader, are struggling, tooth and nail, to adulterate linseed oil and the turpentine product in a way to defy detection.
What the cathode ray is to a certain branch of science, pure raw linseed oil is to carriage and wagon painting. Back in a somewhat indefinite period of the past, linseed oil pre-empted the chief claim in the domain of paint and varnish, and its right to a royal office in that domain has never yet been successfully disputed, notwithstanding the fact that a flood of substitutes and counterfeits have been turned loose upon the market. 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. During the process of painting there are numerous complications which, by the harsh reality of scientific analysis, could be directly traced to the insidious effects of an adulterated brand of oil. Investigations conducted by competent experts have shown that the self-assertiveness of adulterated oil is determined, not so much by apparent unfavorable effects upon the under coats, but rather from its resistless attack upon the lustre and durability of the finishing varnish. Some of the oils used to adulterate linseed oil are pronounced by such authorities as Hurst and Terry to be good driers, although, as in the case of rosin oil, they may seemingly dry good upon the surface only to soften up later on. And provided these adulterant oils are not good driers, the people engaged in floating them along the avenues of trade have simply to add a certain proportion of drying japan to O. K. them in this respect.
The vehicle painter's practice of using raw linseed oil insures him somewhat against oil adulteration, as it is much more difficult to adulterate the raw linseed product than the boiled and have the fraud go undetected. A raw linseed oil when fresh and new is of a bright yellowish-green color, and as it grows older it becomes paler in color and perhaps a little brighter. When spread on a surface in a thin film and exposed to a pure dry air it will harden quite solidly in from forty-five to fifty hours. It ranks as reliable drying oil, promptly solidifying when acted upon by peroxide of hydrogen or by subnitrate of mercury. A non-drying oil refuses to show a change of this kind. Combining powerfully with oxygen, it offers, when dry, a stronger resinous character than any other oil.
Probably the chief adulterants of linseed oil should be listed as rosin, mineral, and fish oil; cottonseed oil being looked upon with less favor than formerly, while hempseed oil, owing to its pronounced tendency to change color, is not much in evidence at present.
Rosin oil is strictly an unreliable drier. It toughens the working property of paint and is deficient in all the essentials which should distinguish a good paint oil. Its low flash point, as indicated by Hurst,--300° to 330° F.--together with its strong rosin odor when heated, would appear to make it an easily-detected adulterant. Deodorizing processes have of late served to fortify this oil, and fish oil as well, against detection by the sense of smell. Fish oil, chiefly the product of the menhaden fishing industry flourishing so vigorously along the Atlantic coast, has naturally an offensively fishy odor, particularly when heated. Its main recommendations as a linseed oil adulterant are tersely summed up by Terry as follows: The rapidity with which it oxidizes, and its good body, render it not unsuitable as a vehicle for paint.
The low cost of mineral oils, including coal oil and petroleum, has caused them to become highly regarded as linseed oil adulterating mediums. Mineral oils more unfavorably affect the drying property of paint than its working and spreading property.
Cottonseed oil belongs to the non-drying class of oils, but since recent processes have made possible the elimination of the pronounced acrid taste, its presence in linseed oil by the sense of taste is not easy to expose.
Hempseed oil is a mean tasting, mean smelling, but good drying oil, and only because of its rapid color changes, wearing finally to a dull brown, is its employment in linseed oil restricted to narrow limits.
In testing for linseed oil adulteration, ammonia is often effectively used, equal parts of the ammonia and oil being employed. Cottonseed oil under the ammonia treatment shows an opaque brown. When it is present in linseed oil the liquid goes to an opaque yellow. Fish oil under the effects of ammonia goes white. Rosin oil will disclose its presence in linseed oil if confined in a bottle, with alcohol added in the proportion of five parts of alcohol to one part of oil, and smartly shaken, the alcohol afterwards being poured off. A clear sugar-of-lead solution is added to the oil, and should rosin oil be an ingredient a cloudy precipitate will manifest itself. A practical and simple test often used in the carriage paint shop consists in taking a couple of test tubes and putting a quantity of linseed oil of known purity in one tube and a quantity of suspected oil in the other, then immersing the tubes in warm water for, say, 1/4 of an hour, and immediately upon removal from the water pouring the pure oil into the tube of suspected oil. If any impurity exists, different colors will form in layers. And it may be here proper to say, in passing, that in making tests and comparisons of materials, an article of established purity and quality should be used as a standard. Some time ago a well-known paint firm issued a card giving some easy and practical tests for the detection of linseed oil adulterants, and knowing their value to the vehicle painter, the writer herewith appends three tests:
No 1.--Shake equal parts of oil and strong nitric acid in a small white glass vial or bottle, and allow to stand from fifteen minutes to two hours.
UPPER LOWER STRATUM STRATUM
Pure } Muddy Almost Linseed oil } olive green colorless
Presence of } Decided deep Deep red or Fish oil } red brown cherry color
No. 2.--Shake with concentrated solution of potash or soda, and then add warm water and shake again. Allow to stand half an hour, and if any petroleum (paraffine oil) is present it will separate from the soap.
No. 3.--Put samples of oil in tubes and place them in a freezing mixture (2 parts ice or snow, 1 part salt). If the oils solidify at 0° or 10° to 13° F., then cottonseed oil is probably present. (Pure linseed oil solidifies at 17° F.)
The hydrometer should be among the possessions of every well-regulated paint shop. It is an inexpensive little instrument, and for testing turpentine it is unsurpassed, while for the detection of cottonseed and mineral oil in linseed oil it is a quick and active agent. First test a brand of linseed oil of absolute purity; and such an oil, bear in mind, should not vary 1/2 degree from 20° to 60° Fahr. In the case of a 20% addition of mineral oil to linseed oil (the same temperature being maintained in testing both the pure and the suspected samples) the specific gravity will be 1-1/2° less than the pure oil. A 25% addition of cottonseed oil will be 1° lower. Fish oil being of about, if not quite, the same specific gravity as pure linseed oil, the adulterator can beat the hydrometer.
Pure raw linseed oil is so essentially a part of durable carriage and wagon painting that especial attention should constantly be directed to the oil supply.
In respect to his purchases of turpentine the painter should be likewise cautious and investigating. The adulteration of turpentine with headlight oil, or a lower grade of kerosene, and with 112 fire test oil has been, and continues to be, actively carried on. This 112 fire test oil, as employed in small southern distilleries not shadowed by inspectors, shows a list of ingredients closely corresponding to, heavy paraffine oil 1/3; kerosene, 1/3; light oil, 1/3. Thus a gravity is provided which registers about the same as pure turpentine and is therefore very difficult to detect. The naval authorities practice--and it is said, successfully--the old-time test of dropping the suspected turps on a piece of white paper alongside of a pure brand of turps and watching the result. The turps containing the 112 fire test oil will leave, upon evaporation, a faint but decided _greasy_ stain. Pure turpentine not too rapidly distilled will leave no spot. The turpentine containing traces of the crude gum due to too rapid distillation will impart a sticky, yellowish-white stain to the paper and this the painter should not confound with the afore-mentioned _greasy_ stain of the adulterated turps. In our Eastern, Middle, Western, and Northwestern cities the practice of kerosene oil injection is the favorite method of cheating the consumer. The sense of smell will sometimes detect the presence of kerosene; the white paper test will sometimes expose it; and again both tests will fail, along with the other usual ones. While so keen an authority as Mr. Geo. B. Heckel, of _Drugs, Oils and Paints_, has acknowledged that the adulterators can cheat the hydrometer to a certain extent, it cannot be done with the same measure of profit and impunity as formerly. Mr. Heckel has publicly advised consumers to insist on 31° turps, prefacing the advice with the following noteworthy declaration: "If I were a painter I would never accept a gallon of turpentine without sticking a hydrometer into it, and if it registered above 31-1/2° or below 30-1/2° I would not accept it from the United States Treasury."
What vehicle painter vested with the authority of purchasing the turpentine supply for a painting business, be that business big or little, can afford to disregard Mr. Heckel's admonition? To pay turpentine prices for kerosene oil is a disastrous drain upon the resources of a painting business, in addition to furnishing the materials used an element of insecurity, a germ of decay, sure to disturb the durability and comeliness of a painted surface. For it is, or should be, in fact, clearly understood that the kerosene or fire test oil adulterants do not evaporate like turpentine when put into a pigment and spread upon a surface. They strike into the wood or pierce the nether coat of pigment, causing, later on, the flaking and peeling of the pigment; or they retard the drying of colors; and again, they lend a peculiar roughness to the surface, like unto that imparted by benzine when used in a fine coach color.
The carriage and wagon painter has substantial reasons for being interested in coach japans, for upon their quality and judicious employment the durability of his work greatly depends. The many and beautiful colors which he uses almost daily are japan ground, and the pigments and colors shop-mixed are invariably fortified with the ever-useful coach japan. The wide variety of names applied to the drying materials used in the painting business has been the source of annoyance and confusion to the practical mind. In reality, however, there are but three kinds--coach japan, specially adapted for colors to be quickly dried and containing no oil; liquid drier (or dryer) intended for the drying of oil and oil paint; and patent driers purchased in paste form, effective only when used in conjunction with oil. The patent driers are so little used at present that they scarcely merit a notice.
Coach japan, with the merits of which the carriage painter has a right to be concerned, being chiefly used, as before stated, in colors containing no oil require, for purposes of protection and as a service-insuring medium, blanketing under one or more coats of varnish.
It is not to be understood that coach japan will not combine with and dry oil colors; its power in this capacity, however, is less than that of a liquid drier, while its gummy nature shows a tendency to cause surface disturbances of the cracking and blistering order--most emphatically so when strictly exact proportions are not maintained. Its adaptability, therefore, is best confined to colors containing no oil.
So much of uncertainty, so much that is injurious and fatal to the durability of colors, is embraced in the employment of japan in excessive quantities or of an inferior grade that the painter should not be slow in determining, by practical tests, both strength and quality. And to make such tests easy, not to mention other convincing reasons, need we invoke the purchaser's attention to the importance of buying only standard makes?
A first-class coach japan, as a rule, will show a color moderately light, and when mixed with oil should manifest no disposition to curdle. Such a japan, too, should, when floated in a thin film over a glass or other strictly non-porous surface, dry firm and without brittleness in four hours. To observe how the japan unites and assimilates with linseed oil, take a pane of window glass, that furnishing a surface non-porous and decidedly free from suction, and attaching a sheet of white paper on one side as a means of better showing the action of the oil and japan, drop on the reverse side of the glass about four drops of raw linseed oil. Then affix, say, a single drop of japan in close proximity to the oil, immediately inclining the glass so that the japan may come in contact with the oil. If the drier promptly unites and takes kindly to a close relationship with the oil without curdling or showing other evidences of disagreement, it will merit the approval of the painter. Another easily-conducted test consists in comparing the japan of unknown quality with one of acknowledged merit, by taking the samples and confining them in bottles containing raw linseed oil, shaking the contents and then standing aside for at least twenty-four hours. The proportions of oil and japan may be in the ratio of 5 parts of oil to 1 part of japan, exactly the same proportions being adhered to in all the samples tested. At the expiration of twenty-four hours one can see which sample mixes best with the oil. The samples then poured in a thin film over a piece of glass and allowed to stand will determine the drying property of each. It will also be useful to learn by observation and comparisons if the japan holds well in solution. A japan that fails to do this is not valuable in carriage and wagon painting. Study should be made as to how and to what extent the japan effects the light and delicate colors at present so extensively used. In point of fact, the painter should not weary in investigating the qualities and characteristics of his coach japans, and what they are capable of doing. To establish their real value will mark an achievement of the first order in the economy of painting.
In regard to varnishes the buyer can find no excuse for putting aside the fact that quality and not price should determine the value of his supply; and, happily, he has it within his power in the active prosecution of his business to demonstrate the good or bad quality of varnish. It may frequently prove an expensive experiment; and herein is disclosed an apparently good and sufficient reason for the painter's disinclination to change from the use of one make of varnish to another. The varnishing stage of painting may be said to be in a critical period at all times, and having established the quality of his varnish supply, the responsible party in the matter is naturally opposed to changing in favor of a make with which he is not practically acquainted. At the same time, a practical test of different strictly reliable makes is the only way of deciding to one's own satisfaction which is the best, and the most economical to buy. Any first-class finisher can very soon determine the working property, brilliancy, depth of lustre, drying quality and general behavior under varying circumstances and conditions of different varnishes. Nevertheless, that primary requisite, durability, is not so easily nor so promptly established. This essential quality can be determined only after protracted trials upon vehicles engaged in active service, the painter retaining carefully tabulated data bearing upon each make of varnish under observation, the character of the service to which it is exposed, etc. Thus, in due season, may the actual merits of a varnish be defined.