A considerable difference of opinions exists among grainers as to the best method of obtaining their grounds, indeed the most experienced men are by no means agreed as to precisely what colour a ground should be. The following mixtures will produce good grounds provided that really first-class colours are employed.
—White lead tinted with a very little vermilion and about an equal quantity of lemon chrome. Some prefer yellow ochre only, others ochre and raw umber in the proportion of four ounces ochre and one ounce umber to thirty pounds of lead.
—Add French ochre to white lead in the proportions of about one hundred and twenty of lead to five of ochre. Add a little burnt umber.
—Eighty parts of white lead to one of yellow ochre produces a good ground, but sixty pounds of white lead, half a pound of French ochre, and one ounce of lemon chrome is sometimes preferred.
—Sixty parts of white lead and one part of golden ochre may be used, or the following mixture if preferred. Six pounds of white lead, one pound of French ochre, two ounces medium Venetian red and two ounces of burnt umber.
—Mix six ounces of lemon chrome to fifteen pounds of pure white lead and add a little deep English vermilion.
—Tint one hundred pounds of white lead with twenty-seven pounds of French ochre, four pounds of burnt umber, and three and three-quarter pounds medium Venetian red.
—Tint sixty pounds of white lead with half pound medium Venetian red, and quarter pound of French ochre.
—One pound of French ochre mixed withten pounds of pure white lead and four ounces of burnt umber and four ounces medium Venetian red give this ground.
—Sixty pounds of white lead, nine pounds of French ochre, and three and half pounds burnt umber.
—Four pounds of medium Venetian red, one pound of orange chrome yellow, and one pound of burnt umber, or a little less burnt umber may be used according to the strength.
—Four pounds of medium Venetian red, one pound of orange chrome yellow, and one pound of burnt umber, or a little less burnt umber may be used according to the strength.
—Mix six pounds of pure white lead with one pound medium Venetian red and five ounces of burnt umber.
—Thirty pounds pure white lead tinted with nine pounds of French ochre, four pounds burnt umber, and one pound medium Venetian red.
—Thirty pounds pure white lead tinted with nine pounds of French ochre, four pounds burnt umber, and one pound medium Venetian red.
—Thirty pounds pure white lead tinted with nine pounds of French ochre, four pounds burnt umber, and one pound medium Venetian red.
—White lead tinted with a very little vermilion and about an equal quantity of lemon chrome. Some prefer yellow ochre only, others ochre and raw umber in the proportion of four ounces ochre and one ounce umber to thirty pounds of lead.
—Eighty parts of white lead to one of yellow ochre produces a good ground, but sixty pounds of white lead, one-eighth of a pound of French ochre and one ounce of lemon chrome is sometimes preferred.
Our examples of graining grounds with their mixtures must be taken as an average arrived at from comparison of the methods employed by different painters in various parts of the country. No doubt some readers will not agree with them and will think that the colour should be lighter or darker as the case may be. As we have explained, the mixtures given are those which may be considered an average, and a variation of them may be made according to individual taste and judgment.
Having given the ground colours, we now proceed to give those which are used for graining. It will be understood that the method of obtaining a graining colour varies just as much as it does in the case of the ground colour, according to the opinion of the painter. The following are given as what may be safely followed to get an average good result.
—Mix one-third burnt umber with two-thirds raw sienna, and add a very little drop black.
—Same as Light Oak.
—Mix raw sienna, vandykes and raw umber with a very little burnt sienna.
—Mix raw umber and raw sienna with a little vandyke brown or ivory black.
—Mix burnt umber, vandyke, raw and burnt siennas, and add a little black or ultramarine.
—Use raw and burnt siennas and raw umber.
—Burnt umber to which is added a little vandyke brown will give a good graining colour for walnut.
—Burnt umber, burnt sienna and vandyke brown, with the addition of a little crimson lake for over graining, will answer well for mahogany.
—Vandyke brown, with the addition of a little black, should be used, and rose pink may be added if desired.
Although to accurately test the quality of a colour requires somewhat elaborate experiments, both chemical and practical, yet there is no reason why the painter should not determine with a sufficient degree of accuracy for his purpose the quality of the colour he uses. Indeed, if this were done more generally, much of the adulterated trash or “muck,” as it has been called, would be driven from the market, and none would rejoice more at such a result than the colour manufacturers themselves. The writer has no connection with, or interest in, these manufacturers, but it is only fair to assert that they are as desirous that the trade should use pure colours as the painters can possibly be. Even the biggest houses produce cheap grades of colours, and this they do, as a rule, almost under a protest and simply because they are compelled by painters demanding colours for certain low prices, far below that which it would be possible to produce the pure article. Our advice, then, to painters is, make a careful comparison between the pure colour and the one you are using. At the same time, compare the prices and then see which is cheaper to use. If even they come out at the same price, remember that by using a pure colour you will have all the benefit of that purity of tone so necessary for the execution of good work.
The first thing to be done in testing any paint material is to have a standard. There must be no doubt about this. Unless we have in each case something with which to compare the particular sample of colour that is being examined, we shall have no useful information concerning it. Take, therefore, good decorators’ colours of well known make. If necessary purchase small tubes of the best colours, such as are put up for artists. This will be rather a severe trial but still it will afford a standard. Having such samples andgoing through the tests we are about to describe, the painter can, after some amount of trouble, arrive at results which are almost as accurate as those which could be deduced by a chemist. An expert on this question some years ago summarised the characteristics of colours which should be considered in making the examination, under the following heads:—
1. Purity of the material.
2. Purity of the tone; brilliancy; richness, which indicate the amount of care in selection.
3. Fineness of grinding or preparation; this means the degree of the division of the particles and upon the completeness of such division will depend.
4. Its spreading capacity.
5. Its body. This applies, of course, only to opaque or semi-opaque colours. Body is opacity, and means capacity to conceal the surface to which the paint is applied, and must not be confused with spreading. It is an inherent quality.
6. Its staining power or tinting strength with white or colours.
7. The quality of purity of the tint with white.
8. If a paste colour, the consistency of the paste.
9. Transparency of transparent colours and the quality of the transparency.
10. The permanency of the colour.
It will be observed that all of these tests will not necessarily be applied to every colour. For instance, a transparent colour would be tested for its transparency but clearly not for its body. The one condition is the converse of the other.
We will now consider the above-named qualities separately.
—This is sometimes of considerable importance, as in the case of white lead, whilst in others—for example the earth colours—it can hardly be said that there is a standard of purity. As a rule a knowledge of practical chemistry is necessary in order to determine whether a sample of paint or colour is pure or not.
The purity of white lead, however, can readily be ascertained by the painter who possesses no chemical knowledge, viz., by aid of the blow-pipe. Take a piece of flat charcoal and cut out a hollow space from it into which place a small piece of white lead to betested, about the size of a pea. Now direct the flame of a blow-pipe upon it, using an ordinary paraffin candle or a Bunsen burner, taking care that the blue portion of the flame bears upon the lead. Keep up a steady blow for a few minutes and the white lead will be converted into metallic lead, which will show in the form of a bright silver-like button. If the lead is adulterated the blowing will only have the result of making it appear like a cinder. To conduct this experiment successfully requires a little practice with the blow-pipe in order to obtain a steady flame.
Another method of testing is to place a little white lead in a crucible and place this on a hot fire, when, if genuine, it will be converted into metallic lead.
A form of blow-pipe that may be purchased at most ironmongers’ shops consists of a wooden handle with a mouth piece filled with cotton soaked in benzine. To this is attached a rubber tube with a mouth piece. This blow-pipe is very easily used, and may be successfully employed in testing the purity of white lead in the manner indicated.
—Some remarks on this subject will be given under the heads of the various groups of colours. Speaking generally, the richness of brilliancy of tone is easily discernible by placing the sample to be tested side by side with another of well known excellence. In siennas, ochres and umbers the selection of crude material by which the richness of tone is assured is of great importance.
—The method of testing the fineness of a pigment usually employed by the painter is to rub a little on the finger nail; but this is a crude and unreliable method. If the pigment is dry and it is desired to compare it for fineness with a similar pigment or white lead, the following is as good a plan as any:—
Take two tall vertical glass jars, place in them an equal quantity of turpentine, and then take a small quantity of the white lead to be tested. Place it in one jar, and an equal quantity of the pigment with which it is to be compared, in the other; thoroughly stir up both and then note the time it takes the samples to settle. If graduated marks are made on the two jars the observations will be taken more readily.
Another test is to weigh out equal quantities of the two leads, and then to take a very small quantity of the same colour, say black, and add to each sample, thoroughly mixing. The lead that is the lightest in colour will be the finest. The explanation of this is somewhat interesting. Suppose that we have a number of cubes of white lead each measuring one inch side. This will give us six superficial inches to be coloured. Now suppose that we break up these inch cubes into half inch cubes, which will give eight half inch cubes to each inch cube. Now as each half inch cube has six faces measuring half an inch by half an inch, it has a superficial surface of three square inches; and as there are eight of the half inch cubes, there are twenty-four superficial inches to be coloured against six in the inch cubes. It will be seen, therefore, that by increasing the fineness of a pigment a greater surface is presented to be coloured, and hence more colour is required.
Another test for fineness is to paint different samples thinned in turpentine on plate glass; when dry the two specimens may be compared and the difference of fineness between them will soon be apparent.
Still another test, and one frequently used by painters, is to place a quantity of the colour ground in oil that is to be tested upon a level surface such as a piece of glass, and to run the blade of a spatula or palette knife over it and then over another sample with which it is to be compared, noticing carefully the difference in appearance of the two samples. By these means the presence of grit is discovered.
—The spreading capacity of pigments and their “body” are very nearly related, although of two equal in body one may possess greater covering power or spreading capacity than the other. A practical method of testing covering power is to mix a small quantity of a standard paint and an exactly similar quantity of the pigment to be tested, taking care to use precisely the same amount of oil and thinners in each case. Then, taking a clean brush for each of the paints, paint a door, or other surface that has been primed, on two panels side by side, continuing to paint till all the pigment has been in each case used up. The one that goes farthest has the greater covering power.In comparing the two it will be well to notice whether the body is equal in both cases, as one may go farther but not cover so well.
—The word “body” as applied to pigments is almost synonymous with opaqueness. It is the most important property of a pigment, and it is because white lead possesses the quality in an eminent degree that it is so much valued.
Body is sometimes called “covering power,” but this term is a little misleading, as some may suppose it to relate to the spreading capacity of the pigment.
If two different white leads ground in oil to an equal consistency are applied to different panels of a door, primed in the same manner, the one of the two leads that possesses the better body will be shown by it hiding the grain of the wood better. Some white leads, especially those that are manufactured by the new processes, lack this important quality of body, and three coats will only cover the work as well as about two of old process white lead.
There are number of methods of practically testing the “body” of pigments, among the simplest being the following.
Prime and paint a board with alternate black and white squares, like a chess or draught board. Take a sample of a pigment, similar to that to be tested, of which the body is known to be good, and paint a wide strip across the chess board; then paint a smaller strip of the pigment to be tested. When both strips are dry, by comparing them one can tell almost at a glance which has the better body, the superior pigment covering or hiding the black squares better than the other. A second coat may afterward be applied to each over a portion of the strip, if desired.
It is important to notice that in all cases of practically testing paints the results are obtained by comparisons being made, and hence it is necessary in every case to have a standard with which to compare the sample to be tested.
The test of painting over squares of black and white may be varied by using stripes instead. The test answers equally well for white lead, zinc, lithopone, or any colour of which the quality of body is of importance. In some colours it is of little moment.
—We have already explained at length how greatly the tinting strength of different colours or stains varies. Any painter can test the tinting strength of anycolour himself in a very simple manner. All that is necessary is to have a pair of apothecaries’ scales, some blotting paper, a palette knife, some pieces of glass or a flat piece of marble and some pieces of waxed paper. First weigh out say eighty grains of dry white lead or dry zinc. Any other white will answer equally well. Place these eighty grains on one side of the glass and the second eighty grains on the other. Now take the dry colour and weigh one grain and add that to one of the little piles of white, then weigh a grain of the standard colour and add that to the other pile. Now add to each pile a few drops of oil, taking care that the number of drops is the same in each case. With the palette knife thoroughly mix until no streaks can be seen and the mixture is perfectly uniform. Then by comparing the two the difference in tinting strength will at once be apparent. The same result would have been produced had ordinary white lead ground in oil been used instead of dry lead or zinc. If the colour is ground in oil a little difference in the method must be observed, the reason being that one colour might be ground much thicker than the other, in other words, might contain much more oil than the other, and hence if equal weights of each were compared the result would be misleading. Take then each colour in oil—that is the standard and the colour with which it is to be compared—place on a small quantity of blotting paper and allow it to remain a few minutes so that the oil may be extracted. If it is thought necessary the sample can be washed with benzine, but for painters’ purposes the extraction of the oil by means of blotting paper is sufficient for the purpose. The two samples having remained on the blotting paper for a short time one grain of each is weighed out separately on little pieces of wax paper, this being used so that the colour shall not stick to the scale. Then each grain is mixed separately with the white and the result compared as before. It is not too much to say that every painter should be prepared to make this test because it informs him not only as to the tinting strength of the colour but also gives valuable information as to the tone, etc. Of course the quantities may be varied if necessary, and a larger amount used instead of the single grains. It need hardly be pointed out that scrupulous cleanliness is necessary for successfully carrying out this test. The palette knife must be wiped between each operation and every care taken to do justice to both samples.
If the reader will turn to the samples of colour issued in this work he will see a number of colours given in their full strength, and also when reduced with certain parts of white, as marked upon the sheets. The colours used in the preparation of this sheet were of average quality, and it will prove interesting no doubt to the student to mix the colour he has been in the habit of using in the same proportion with white and to note whether the results come out above or below those shown by our samples.
—It must be admitted that it is very disappointing to a painter to find, after taking pains to produce the exact colour required, that it flies or fades after a little exposure to the weather. The tests for the permanence of a colour when exposed to light are simple enough and are to mix a little of the colours to be tested in oil and to spread them on different slips of paper, cut the paper in half, number each half with corresponding figures or letters, expose one half to a strong light for as long as may be deemed desirable and put the other half away into a safe place where the light does not penetrate. Waxed paper is the best, as it will not absorb the thinners or, better still, glass may be used, this being cut across with a diamond after the paint has been applied. It need hardly be said that the permanence of water colours is entirely different from that of oil colours. Some very useful experiments were made several years ago by Capt.Abneyon the permanence of water colours, and these were published in the form of a blue book. As far as pigments are concerned, we consider that yellow ochres, siennas, umber, Vandyke brown, and the earth colours generally are permanent, as are Venetian red, Indian red, chrome yellow, and lemon yellow. Ultramarine, Prussian blue and vermilion are also permanent or nearly so.
We may now take each colour separately following the order taken by the late Mr.W. C. Wilson, who arranged the above quoted table in conjunction with the author.
—This colour is often made by the addition of a base such as barytes, but the presence of this material is not at all necessary, although the presence of the earth for some reason assists in producing the mixture of Prussian blue and chrome yellow whichis used to produce chrome green. A number of different shades of chrome green are sold, usually designated pale, mid (middle or medium) and deep. The tinting strength should be tested by mixing one part of green to, say, a hundred parts of white lead or zinc, as explained elsewhere, or twenty-five parts of lead may be used to one part of green. If it is desired to find out the relative strength for tinting purposes of the green, it can be done very simply in the following manner, but the painter must have a pair of apothecaries’ scales, in order to weigh the different quantities. Take first the same quantity of the green which is being tested as that of the standard. If the colour is not so deep add more green each time, and more and more until the two samples are exactly the same tint. By comparing the weights the experimenter will have accurately the relative value of the two greens for colouring purposes. The test for body of the green is performed in almost exactly the same way as that already described for white lead. Prime a board thoroughly so that there may be no absorption, paint across the centre of it a stripe of white and by its side a stripe of black. When this is thoroughly dry take the two greens; that is, the standard and the one being tested. Then mix both with exactly the same amount of oil and turpentine. Take a clean brush for each and paint over the black and white stripes. The one which has the greatest body will, of course, hide the stripes better than the other one. The experiment is simple, and is very useful as a body tint.
—This colour is usually mixed by the painter and not bought ready made, although all manufacturers make bronze greens. Quaker green is practically the same thing. The mixture usually employed is ochre, lamp black and a little yellow. The chrome should be either yellow or orange, but not lemon. Bronze greens may be made in a large variety by varying the quantities of the colours mixed and by introducing sienna, umber or Indian red in small quantities as may be required. The colour is very rich, and many cheap bronze greens consist of a considerable quantity of adulteration.
—This is most entirely without body, but is the most brilliant green known. It is therefore sometimes used where brightness is required. When ground in oil the test for purity is to dissolve it with benzine and when the dry powder isobtained to treat it with strong ammonia. It will thus entirely dissolve if pure, giving a deep blue colour.
These colours may be classed as the iron colours, consisting largely of oxide of iron. It should be remembered that ochres and umbers also receive their colouring from iron. Analysis gives but little information concerning the value of this group of colours. They form economical paints, especially as they spread well. The proportion of oxide of iron contained is often considered to be an indication of quality, but this refers particularly to cases where paint is to be used on iron. The tests of value to the painter are body and fineness of grinding, which may be tested in the usual way. Oxide paints are usually sold as such in three shades. A Venetian red is lighter than an Indian red, which, in comparison, should have a purplish tint. It must be remembered in this class of colours that a comparison of the same shades must be made if any useful result is to be obtained.
is a mixture of Indian red with some sort of lake colour in order to secure brilliancy. This brilliancy forms an important feature of the test; body should also be ascertained, and fineness of grinding is also important. Tuscan red, which is coarse, may lose its richness when ground fine.
—Many of the imitation vermilions consist of orange red, that is, a superior red lead coloured with eosine, which is the name of one of the coal tar colours. Speaking generally, the scarlet colours are more permanent than those having a crimson tinge. It is important to know that the tinting strength for many vermilionettes is no indication of their quality or rather, perhaps it should be said that within reasonable limits the better stainers they are, the worse colours they will prove to be. This is because barytes or some other mineral may be substituted for the orange red and then the eosine will go farther in staining.
—Every painter knows that the great objection to the use of red lead is that it will harden quickly. We recommend that on large jobs arrangements should be made with a manufacturerto supply a sufficient quantity for two or three days. It should be well ground to a thin paste in the proportion of, say, about one pound of oil to five pounds of red lead. The usual manner of painting iron, etc., in red lead is to first give a priming coat of pure lead and then a second coat of any colour desired. An excellent second coat is formed of equal parts by weight of red lead and good iron oxide. Any finishing coat may be applied.
—This is shown by analysis to consist almost wholly of oxide of iron. The paler Indian red is, the greater is its tinting strength and the rosier is the tint obtained from it by mixing it with white. Indian red should be always tested for fineness and tint.
There are many shades of chrome yellows sold, the most usual being lemon, medium and orange chromes, sometimes called 1, 2, and 3. The other shades are sold under various names, depending upon the manufacturer. It is advisable that the painter should always have on hand the lighter shades, as although it might appear at first sight that on mixing the deeper shades with white he would get the same result, as a matter of fact there is a considerable difference. As noted elsewhere, chromes must not be mixed with ultramarine. The pale chromes change colour quicker than the darker shades. Pale chrome should never be used on fresh plaster, although orange chromes may. In the deeper shades of chrome orange red is sometimes used as an admixture or adulterant, but this is not a good stainer. The test for a chrome is tinting strength, taking care to make a comparison with the same grade of colours, that is, light, medium or orange chrome. Fineness is another important test. Placing a small quantity on glass and passing a palette knife over it and pressing firmly will detect grit if present. In the lighter chromes it is well to look for the greyness of tone which is objectionable. Chromes mix well with white lead and are strong in body.
—Analysis is of no value in determining the value of an ochre. Sometimes chrome yellow is used to tone it up. The colour is an important feature, as is also the fineness.
There are a number of blacks on the market, drop black, ivory black, blue black, vegetable black, carbon black, etc. The subject of their tests is a somewhat intricate one, but its tinting strength can be readily ascertained by mixing with white lead or zinc in the manner already described. They are frequently adulterated with barytes.
Prussian blue is one of the most important used by the painter. It is very strong and a little goes a long way. It must be very finely ground or it is likely to settle out. A pure Prussian blue has a rich bronze appearance when looked at from certain points of view. The tint made by mixing with white should be clear and free from any leaden or gray appearance. Some Prussian blues have a certain red or purplish cast which cannot be removed. These should be avoided, as if a purple is required it is a simple matter to add a little red to the blue to produce the desired colour. As shown in our samples of paint, one part in a hundred of good Prussian blue gives a distinct sky blue.
—As explained elsewhere, this colour cannot be mixed with white lead. Where it is necessary to make a tint, zinc white should be employed in preference.
The colour should be a rich brown rather than a red cast. In siennas prepared for grainers’ use, it is important that they be transparent rather than opaque. Richness and quality of tint should be considered rather than the body.
Speaking roughly, about one-third of the value of a common painting job will be for labour and the rest for material.
A good priming coat for wood may be composed of ten pounds white lead, two ounces red lead, two ounces driers, and four pints of linseed oil. The following coats having about two pints of turpentine instead of an equal quantity of linseed oil and the red lead being omitted.
A mixture for removing old paint is made by taking one pound soda and quarter pound quicklime and mixing to the consistency of cream. This is applied to the paint work with an old brush and left for about an hour when it will be found to have softened the paint which will readily wash off. The work may then be washed down with weak vinegar and water.
One gallon of oil varnish may, for the purposes of calculation, be taken to cover sixty-four square yards.
Seven pounds of ordinary white lead paint may be taken to cover rather more than thirty square yards for the first coat and forty-five yards afterwards.
Seven pounds of oxide of iron paint will, if good, cover about eighty square yards on iron, but the quality of oxide varies considerably.
To prevent plaster of Paris from setting quickly mix with glue water instead of ordinary pure water. This will retard the setting considerably.
—Make two solutions, the first to consist of one and one-quarter pounds of glue, dissolved in four gallons of water; the second to consist of one ounce of borax, five ounces of washing soda and twenty ounces of powdered rosin added to five quarts of boiling water, and to be kept boiling and stirred until all is dissolved. To thirty parts by measure of the first solution add one part of the second and boil them together for about one-quarter of an hour; take from the fire and strain; when it is ready for use. This size is an excellent one for the purpose.
—Mix in a quart of hot water a quarter of a pound of Turkey umber and add two tablespoons of turpentine.
—Grind fine in water half a pound of raw Turkey umber and half a pound of Dutch pink. Dilute with one gallon of water and add half a pint of vinegar.
When vermilion is used in distemper it is necessary to stir it up now and again as the colour sinks to the bottom.
Cleanliness should be the first and foremost rule for every painter. It has been said that if it were not for the flies and the smoke the principal part of the painters’ occupation would be gone. It may be taken as a safe rule that all old work should be thoroughly washed down with clean water before repainting. This pays even with stucco or outside cement work.
A good priming coat for work that is to be finished in vermilion is made by mixing bright Venetian red and white lead with boiled linseed oil.
—Pilkington’s “Glass Cutter’s Assistant” gives the following: Polished, Silvered, and Rough Cast. All fractional parts of inches will be charged as full inches, e.g., 1051⁄8× 571⁄4be reckoned as 106 × 58.
—Every fraction above1⁄6of an inch is charged as an inch, e.g.,
—
One of the best tests for linseed oil is its weight or specific gravity. The latter term is not so well understood among painters as it might be. A few words of explanation may therefore be given. One hundred gallons of pure water when weighed when the temperature is at 60 deg. F. weigh exactly 1,000lbs. This is taken as the standard of specific gravity for all liquids, and a scale or hydrometer is based upon it. One hundred gallons of boiledlinseed oil at 60 degs. F. weigh only 940lbs., and the specific gravity of linseed oil is therefore said to be ·940. As it would be practically impossible to weigh as much as 100 galls. of the liquid which it was desired to test for specific gravity, an instrument called the hydrometer is used for the purpose. This floats in the liquid and bears a scale so that a portion of it stands out of such liquid. When put in pure water, the indicator would show, of course, at 1,000, and in boiled linseed oil ·940, and in raw linseed oil it would show about ·922, which is the specific gravity of raw oil. Cotton seed oil raw is the same as raw linseed oil, namely ·922; colza oil is ·915. In actual practice the specific gravity of oil is taken by means of a bottle or flask which is weighed when full of oil and then compared with the weight of the same bottle full of water.