Painting by Immersion and by Compressed Air: A Practical Handbook

Safe Baking Heats of Pigment Colours.

All colours are more or less affected by heat. They lose their brilliancy, become very much darker and sometimes turn black when baked at too high a heat.

Prolonged heat (not too high) kills the elasticity of the enamel. It does not affect the colour.

To assure brilliancy of the colour, the following highest heats can be used with safety.

Comments on the Above.

A well-known English firm, commenting on the above says:—

"Generally speaking, the information given therein is quite correct, though it should be remembered that instruction as to stoving temperatures which might be quite correct with one maker's materials, might be quite wrong with another's.

"We notice they recommend that all black japan finishes should be stoved at from 250 to 350 degrees. This is the general practice in England, but it also happens that some firms cannot use these high temperatures or some goods will not stand it, and black japans have to be supplied which can be stoved at temperatures of about 180 or 200 degrees Fahr. Such qualities cost rather more to produce.

We also notice it is recommended that finishing varnish should be stoved at 175 degrees Fahr. Personally, we cannot make any clear finishing varnishes which will stand this temperature without discoloration, and even if used over black japan, they would discolour the lining or the striping thereon.

"The temperatures recommended for coloured enamels are also higher than we find satisfactory, and the statement made that the same enamel will bake to different shades at different heats, and that therefore a uniform temperature is necessary to obtain uniform results, seems to confirm our view. In practice we think that uniform results can only be obtained by using a lower temperature. If a workman has to watch the thermometer in a stove to make sure that his enamels will always discolour to the same degree, you can rely upon it that in practice accidents would soon happen."

Dipping and Spraying Paints Compared.

From the above it can readily be seen that it is necessary to exercise considerable care in the selection of paints for both of these processes. The following opinions on this important subject are given by the firms named.

Messrs. John Lucas and Co., Inc., Gibbsboro', N.J., U.S.A., say:—

"It is our experience that a paint which is suitable for dipping purposes can also be manipulated for spraying. A paint to be suitable for spraying depends largely on two factors, namely:—Gravity, or weight per gallon, and consistency, or fluidity. A paint made from pigments which are heavy gravity will not produce good results for spraying, just as it will not prove satisfactory for dipping, because of the tendency for the pigment to settle out. In the case of spraying such paints produce an uneven finish. A paint such as is ordinarily used for dipping contains sufficient light gravity pigments to make possible reduction with the proper vehicles (depending on the desired finish) so that by spraying a satisfactory coating can be produced so far as finish is concerned. We are not certain whether a coating produced by spraying will wear as long as a coating which is applied either by dipping or by brushing."

The Chicago White Lead and Oil Co., Chicago, Ill., say:—"There is no very intricate or specific formula for this class of material. The following rule we think will prove a safe one to follow:—

"Always select a pigment which will stay in suspension, and also hold with it the extenders such as very fine silica. The addition of a very fine silica to all dipping or spraying paints will add materially to the flowing off and levelling of the finish. The pigments should be ground very fine in varnish, the grade of varnish depending upon the quality of the material to be produced, and reduced to working consistency with varnish and turpentine, or naphtha.

"Linseed oil should be avoided in the preparation of dipping paints, as the tendency of linseed oil to wrinkle is very objectionable. Chemically pure colours, such as green, yellow, para toners, etc., are best adapted as colour bases.

"The above constitute the principles upon which we have produced extremely satisfactory paints for the purpose named. These, coupled with expert workmen, will produce excellent results. The average formula for paints can only be considered as a general guide; the successful blending, tinting, etc., must be perfected by careful and sometimes extended experiments.

"The difference between a dipping paint and spray paint is in the consistency. A spray paint must naturally be made thinner, and consequently only the most dense of colours should be used and a smaller amount of inert pigment as an extender, or leveller. A few experiments with a spraying apparatus (of which some inexpensive hand sprayers can be obtained) will quickly guide the paint man as to proper consistencies to produce best results."

Messrs. John W. Masury and Son, of New York:—"It is practically impossible to give full particulars regarding varnishes and enamels for spraying and dipping, for the reason there are so many different kinds and they vary so much owing to the different character of work that a description of them is out of the question. In a general way it may be said that dipping coatings must be quick setting, so as to avoid runs and sags; it must flow out to a smooth, even surface. The drying quality must depend upon the kind of work being done, character of surface, subsequent exposure, and whether the coating is to be baked or air dried. Dipping varnish and enamels are made for many classes of work, such as all kinds of small iron castings and sheet metal work, as well as wood work, vehicle wheels, parts of automobiles, and in some cases wagon bodies and automobile bodies, these last only in one or two shops. These goods include cheap black baking japans, coloured enamels of various kinds and clear varnishes.

"In regard to spraying enamels, the 'spray brush' is gradually coming into use. These goods must be made to suit the character of the work; the body or viscosity of the material, the pressure used in the spray and character of the surface to be coated, must all be taken into consideration and properly graduated to insure suitable finish.

"In both dipping and spraying work one, two and three coats are frequently used, sometimes the under coats are only dipped or sprayed, while the finishing coat is applied with brush.

"The equipment for dipping will vary also with the article to be dipped; it includes dipping tanks of suitable size and shape, racks for hanging articles dipped, with troughs or trays to collect surplus material. In dipping it is necessary to wipe off with brush the surplus which gathers on lower edge of the article.

"Equipment for spraying requires besides the spraying machine a pressure tank with suitable cocks to regulate pressure, which will vary from thirty to fifty pounds, a suitable hood provided with fan to draw off any fine spray away from the workman, proper racks for taking care of the finished work. Work done with spray does not require any wiping up."

CHAPTER XI.

To spray the same body takes only 6 to 8 minutes, and when it is noted that a fraction of the rubbing down is necessary in the case of the sprayed result, as against the brushed body, it will be granted that an enormous gain is to be effected.

Where two or more colours are employed, it is difficult to make comparisons as readily, but, generally speaking, it is the practice to employ two instruments per operator where the colours are applied one immediately after the other, as is the case with many electrical parts, and in this case a gain of 4 or 6 to 1 is shown over brushed work.

In some cases it has been found an advantage to spray one coat and to brush the other, especially where some difficulty is experienced in masking, and, in such cases, the only way to arrive at the most satisfactory method is by actual test.

In other cases, such as bronzing, with a celluloid medium, it is absolutely impracticable to apply these bronzes, save with the spray, unless the old method of varnishing and afterwards dusting on the bronze is adopted; but, of course, against spraying, such an obsolete method as the latter has absolutely no chance when speed is considered.

Iron piano frame manufacturers have almost universally adopted the system of spraying bronze on the frames. Where the old-fashioned method is still in use, it is usually because the quantity of frames to be dealt with is hardly large enough to justify the outlay required in the purchase of a plant.

Another advantage should be mentioned. The special celluloid japans now largely used for application by means of compressed air obviate the necessity of a considerable amount of rubbing down and papering, etc., which cannot be dispensed with when the liquid is applied by means of a brush.

For the purpose of comparison, it may be said that these japans may be sprayed upon such articles as buttons, medallions, electrical and bedstead fittings, and also on wood brush-handles and furniture, large and small, with a gain of 5 to 1 over brushing.

Objections Sometimes Urged Against Spraying.

Having explained the advantages of the spraying system, we may now consider the objections which are occasionally raised against it.

One of the arguments most frequently used is that the effect thereby obtained must be less durable than is the case of the brushed effect.

Why such a theory should be advanced is a little obscure, for, theoretically, it is possible to apply, with a properly fitted plant, a far more even coat than is the case when brushing, and seeing that such paint is applied with the idea of protecting the article against rust, or corrosion, or of improving the appearance, the argument is for rather than against spraying.

However, to come to the practical side, the evidence is all in favour of spraying, for it has been proved by many exhaustive tests by independent persons, that, with the same material treated in the same manner, i.e., either air dried or stoved after spraying or brushing, there is no difference in the durability of the japan or paint, and that the sprayed result has this advantage, that some little gain in time is effected in the period occupied in drying or stoving of the paint.

Another objection is sometimes raised to the application of paint by means of the spray to rough and uneven surfaces. The argument here is that it is impossible to make the paint adhere to the surface, save with a good stiff brush.

Such arguments ignore the pressure at which the paint is applied, which is usually between 30 and 45 lbs. per square inch, and are mainly based on unfortunate experiences with early types of whitewashing machines, which have already been pointed out to be entirely unsuited to painting problems.

Again here, it may be positively stated that in no case has it been found that a less durable finish is obtained with the spray. As a fact, an advantage is to be recorded in that on rough surfaces the gain in time is enormous, for such surfaces may be spray-painted as rapidly as the smoothest surface obtainable, whereas the labour of brushing such rough surfaces is very considerable.

Still another objection which may be mentioned is the slightly mottled appearance which the sprayed surface sometimes shows when finished—if such can be objected to seriously.

This objection may be met by the statement that such a mottled effect is only apparent when the paint has not been specially prepared for spraying, and is mainly due to the fact that mediums used dry rather too rapidly and do not allow the paint (which is, of course, applied in minute spots) to flow out.

The remedy is naturally to re-model the paint should the mottled appearance be objected to, but most certainly such an effect, if not pronounced, is not any worse than brush marks, which are always noticeable unless rubbing down has been done.

In passing, it may be stated that most of the large paint and varnish manufacturers have experimental plants for producing spraying materials, and they are naturally well able to answer any queries which may be likely to arise and which may not be adequately dealt with here.

Many firms who consider the question of adopting a spraying plant seem to have the idea that while the principle is admirable for many trades, yet it cannot be successfully employed in their particular case, and one frequently finds the manufacturer of small goods wondering why his neighbour opposite, who makes, we will say, motor bodies, does not install a plant, although, of course, in his own case the question is impossible. Most probably, at the same time the said neighbour has precisely similar thoughts, save that he considers the only proper use for a plant is in small work.

Occasionally one hears the opinion advanced that primers or fillers cannot be applied with a sprayer, or, if so applied, it is at a risk that they will either crack or peel off afterwards.

This objection may just as readily be advanced in the case of brushing. If trouble of this kind occurs, it is not due to the method of spraying, or brushing, so much as to the way in which the paint has been used. This statement sounds paradoxical, yet it will be understood by practical men. For instance, it is obvious that motor bodies, par exemple, must be dealt with by the expert coach-painter as far as the methods, number of coats, etc., to be employed are concerned, even though the work may be carried out by unskilled labour, and naturally whether brushed or sprayed, motor bodies cannot be well done by novices.

To summarise, it may be confidently stated that whatever difficulties there may be in the application of paints, enamels, varnishes, lacquers, etc., by means of brushes in the ordinary way, these are certainly never accentuated but are in most cases considerably lessened by the use of an adequate spraying plant.

Spraying and Dipping Compared.

In considering those articles which may be dealt with either by dipping or spraying, the manufacturer has first to take into account the number of coats necessary.

If, for instance, to produce the correct finish on a cycle frame, when dipping, needs three coats, and assuming that the same effect may be obtained in two when spraying (and this is frequently the case), then spraying must be considered to rank favourably with dipping, and if allowance be made for the time taken to drain, and the room occupied with an elaborate dipping plant, then again spraying scores, for a cycle frame can be sprayed in 1 to 1½ minutes, or, say, 40 to 50 frames per hour, which is very little, if any, less than can be comfortably dealt with by dipping, and, of course, no time is lost in draining.

If, on the other hand, gas is so cheap as to be of little consequence whether two or three stovings are necessary, and if some of the work can be done with two coats, then the saving effected when spraying would not be sufficient to warrant the outlay necessary for a modern compressed air plant, unless a fair proportion of coloured work, not easily dipped, was required to be dealt with. In this latter case, a spraying plant ought to receive very serious consideration.

To take another case. Some gas fires may be dipped, but, owing to their weight and to the fact that they are seldom entirely free from grit or dust, they are not a satisfactory type for dipping, and we venture to state that all the leading gas engineers have dropped the question of dipping such work in favour of spraying, although in some cases, for gas cookers, the accessories, such as burners, bars, racks etc., are dipped.

Such accessories are as readily sprayed, but as only one coat is applied, naturally no saving is shown over dipping.

Other goods sprayed or dipped are steel implements, hoes, spades, shovels, axes, picks, etc., and in some cases it is an advantage to dip where the same colour, black, red, etc., is needed, say, half-way up the spade or hoe, but otherwise spraying should be adopted; and, of course, in many cases where two colours are employed it is out of the question to dip, the only alternative being to spray or brush—spray for preference on account of the enormous saving of time over brushing.

Where very small articles are dealt with in bulk and can be so handled that trays may be used, then these are undoubtedly better dipped; but if various colours are needed it is better to still use the trays, but to spray them, as the speed is approximately the same as when dipping.

A tray full of camera parts is sprayed almost instantaneously and with a far better finish than if dipped.

To sum up the various arguments advanced on this subject, we may come to the following conclusion.

As already intimated, the saving effected by painting by immersion or by spraying as compared with brushing is very large indeed, provided that a properly equipped plant is employed, and the paint or enamel is exactly fitted for the purpose. The question must often arise as to whether dipping or spraying is the best and cheapest to employ. The answer is that everything will depend upon the nature of the article that is to be painted. Speaking generally, painting by immersion possesses many advantages, because the actual work of applying the paint is done in a few minutes and every part of the article is covered with paint at one time. In reaping machinery, iron treads of staircases and many other parts of the kind in which there are a large number of small parts or depressions, paint dipping cannot be improved upon; on the other hand, spraying possesses distinct advantages in dealing with many classes of goods which are of such a shape or character that if the paint were applied by dipping some accumulation in parts would inevitably occur.

A decision on the subject can only be arrived at after a very careful study in comparison of the two methods. It will frequently be found that, on the whole, the most economical plan to pursue is to dip the first and subsequent coats, excepting the last, and to spray this on, particularly when it consists of varnish or a viscous liquid. It is in this particular that one can draw a wide distinction between the two methods. In dipping, the paint must not be very thick, and, as previously stated, in designing a paint for the purpose the greatest effort is made to produce one which gives a happy medium between excessive thickness and the reverse, too thin a coat. Just as soon as the peculiarities of the article to be painted necessitate the use of all thick paint or enamel it must be considered that dipping is not suitable, but that spraying is. The latter may be employed successfully with any liquid up to the thickness of tar.

CHAPTER XII.

In relief work, such as ornamental iron, pressed paper, etc., some pretty effects may be produced by spraying a different colour to that of the ground in such a manner that only one side of the relief receives the second colour. This is effected by directing the spray from the side. Most readers will be familiar with these effects produced on menu cards, concert programmes, etc. The possibilities in connection with relief metal work are many.

Another series of effects in which brilliancy of colouring is required may be referred to in passing. Sometimes a bright red or a bright green is desired for the finish of a particular piece of work. In such cases a use of the process known as "colour glazing" is recommended. For example, an agricultural implement or any other article which it is desired should have a bright crimson finish can be first painted with Venetian or Indian red, by either spraying or dipping, and then have a coat of crimson lake, which will give an excellent effect. As the crimson lake is somewhat fugitive a protecting coat of varnish will be required.

All glazing colours may be applied by dipping, because, being semi-transparent, they are all very fine, and the coats may be thin, but the varnish should be applied by spraying or by hand. It may of course, be of a variety suitable for baking or stoving if required.

This process is an alternative to using coloured enamels, and in some cases gives better results. Much depends upon the colour and the constituents of the enamels. Many of the lakes are very sensitive to a high heat, which changes the colour to a dirty brown. In such cases a final coat of stoving varnish, if carefully handled, will be safer than some grades of enamel.

Scumbling and Colour Glazing.

For convenience of reference we include a short list of glazing colours taken from Andrew Miller's "Scumbling and Colour Glazing," published by the Trade Papers Publishing Co., Ltd., 365, Birkbeck Bank Chambers, London, W.C.

Glazing.

The principal colours used for glazing are cadmium, crimson lake, Prussian blue, lemon and orange, chrome, yellow, Brunswick green, carmine, madder lake, Chinese blue, cobalt, indigo, gamboge, terra verte and emerald green. These colours may be used ground in either linseed oil, turpentine or water. Some of them are rather expensive, but the coat being very thin a little colour goes a long way.

Following is a list of ground colours with the glazing which may be used in conjunction with them. They by no means exhaust the range of effects, but are given as suggestions:—

REDS.

Apricot.—Ground made up with zinc white, middle chrome, and vermilionette, glazed with crimson lake.

Begonia.—White zinc, vermilionette and Prussian blue, glazed with brown madder lake.

Carnation.—White zinc and vermilion, glazed with crimson madder lake.

Claret.—Zinc oxide, Venetian red and vermilion glazed with brown madder lake; or zinc oxide and ultramarine blue, glazed with carmine.

Coral.—White zinc, vermilion and lemon chrome, glazed with crimson lake.

Flesh Colour.—White zinc, yellow ochre and Venetian red, glazed with burnt sienna.

Geranium.—Bright Derby red and orange chrome, glazed with crimson lake.

Lilac.—White lead, vermilion and ultramarine blue, glazed with brown madder lake.

Magenta.—Zinc oxide and ultramarine blue, glazed with crimson lake.

Peach.—Zinc oxide, vermilion and lemon chrome, glazed with cadmium (deep); or white lead and Venetian red glazed with carmine.

Plum.—Zinc white, Indian red, and ultramarine blue, glazed with carmine; or white lead and Indian red, glazed with ultramarine blue.

Pomegranate.—Zinc white, Venetian red and lemon chrome, glazed with burnt sienna.

Russet.—Venetian red, orange chrome, lemon chrome, glazed with emerald green (thin).

Rose.—Zinc oxide and vermilion, glazed with crimson lake; or white lead and lemon chrome, glazed with carmine.

Terra-cotta.—White zinc and Venetian red, glazed with burnt sienna.

BLUES.

Azure Blue.—Zinc oxide and ultramarine blue, glazed with cobalt.

Bronze Blue.—Zinc white and Prussian blue, glazed with black japan.

China Blue.—Zinc white, cobalt and raw sienna, glazed with indigo.

Gobelin Blue.—White, blue black, Prussian blue, glazed with emerald green.

Marine or Sea Blue.—Ultramarine, ivory black, glazed with cobalt; or white, raw sienna and cobalt, glazed with indigo.

Metallic Blue.—Zinc white and cobalt, glazed with emerald green; or zinc oxide, Prussian blue, black, glazed with indigo.

Mauve.—Zinc oxide and cobalt glazed with carmine; or zinc oxide and celestial blue glazed with carmine.

Peacock Blue.—Zinc oxide and ultramarine, glazed with emerald green; or zinc oxide and Prussian blue, glazed with cobalt.

Turquoise.—Zinc white and cobalt, glazed with emerald green.

Wedgwood.—Zinc white, Prussian blue, glazed with terra-verte.

YELLOWS.

Amber.—Zinc white, golden ochre, glazed with cadmium (deep); or white lead and lemon chrome, glazed with cadmium.

Antique Brass.—Zinc white lead, orange chrome, glazed with Vandyke brown or black japan.

Brass.—Yellow ochre, white lead, orange chrome glazed with Vandyke brown.

Canary.—Zinc white and Naples yellow, glazed with emerald green (thin).

Chamois.—Zinc white and middle chrome, glazed with terra-verte.

Citron.—Zinc white and middle chrome, glazed with brown madder lake (thin); or white lead, Venetian red, lemon chrome, glazed with Prussian blue.

Daffodil.—Zinc white, lemon chrome, glazed with burnt sienna.

Gold.—Zinc oxide, golden ochre, vermilionette, glazed with raw sienna.

Old Gold.—Middle chrome, vermilion, burnt sienna glazed with cobalt (thin); or zinc oxide, Oxford ochre, glazed with burnt sienna.

Primrose.—Zinc oxide, lemon chrome, Naples yellow, glazed with emerald green.

Topaz.—Zinc oxide, raw sienna, lemon chrome, glazed with cadmium (deep).

GREENS.

Apple Green.—Zinc oxide, Prussian blue, glazed with cadmium (middle); or lemon chrome, zinc oxide, celestial blue, glazed with lemon chrome.

Duck-Egg Green.—Zinc oxide, lemon chrome, glazed with Prussian blue.

Eau-de-Nil.—Zinc oxide, lemon chrome, Prussian blue, glazed with emerald green.

Grass Green.—Zinc oxide, Oxford ochre, glazed with cobalt.

Ivy Green.—Zinc oxide, lemon chrome, burnt sienna, glazed with Prussian blue.

Myrtle Green.—Zinc oxide and ultramarine, glazed with emerald green.

Olive.—Zinc oxide, lemon chrome, burnt sienna, glazed with emerald green.

BROWNS.

Chestnut.—Yellow ochre and middle chrome, glazed with burnt sienna; or burnt sienna and orange chrome, glazed with Vandyke brown.

Chocolate.—Burnt sienna, vermilion, ultramarine glazed with crimson lake; or burnt sienna and Indian red, glazed with Vandyke brown.

Cherry.—Raw sienna and burnt sienna, glazed with raw umber.

Nut Brown.—Venetian red, lemon chrome, zinc oxide, glazed with burnt sienna.

GRAYS.

Cool Gray.—Zinc oxide and ivory black, glazed with Prussian blue.

Dove.—White, ivory black, Prussian blue, glazed with terra-verte.

Fawn.—White, raw sienna, glazed with raw umber.

Heliotrope.—Zinc oxide, vermilionette, glazed with ultramarine.

Lavender.—Zinc oxide, ultramarine and carmine, glazed with cobalt.

Mouse Gray.—Zinc oxide, Prussian blue, glazed with burnt umber.

Pearl Gray.—White, Prussian blue, and vermilion, glazed with terra verte; or zinc oxide, vermilion, glazed with emerald green.

Silver Grey.—Zinc oxide, ivory black, glazed with indigo.

Opal.—Zinc oxide, celestial blue, glazed with burnt sienna.

Warm Gray.—Zinc oxide, Venetian red and ivory black, glazed with Vandyke brown.

Wedgwood Gray.—Zinc oxide, Prussian blue, glazed with terra verte.

Note.—The terms "Zinc white," "White zinc" used above, all mean pure zinc oxide.

Scumbling and Graining.

It is sometimes desired to obtain a different effect from plain paint or enamel, and to either imitate graining, such as old oak or to give mottled effects. Both processes are produced by scumbling, which means that the ground and finishing colours are different in hue or in intensity, and that portions of the latter are removed to show part of the ground. Thus, in imitating oak, the ground might be painted with a mixture of zinc oxide and yellow ochre, and the graining colour be made of burnt umber and raw sienna. Both coats could be applied either by dipping or spraying, but while the latter is wet, portions should be removed by combs and by the thumb held over a piece of rag, both marks being intended to represent the grain of the wood. In other cases, the colours may be applied as before, and the last coat, while wet, be wiped away at the edges, or in the case of relief metal work, at the highest parts. Again, some excellent effects are obtained by using different colours for the two coats, as suggested, and stippling the second, while wet.

Space will not permit of a more lengthy reference to this part of the subject, but full information can be obtained from Mr. Miller's book already mentioned. Something should be said, however, about

Brush Graining,

because it is so very well suited for work of this character, and by its use some very pleasant effects may be produced.

In this case, a material such as "Matsine," or "Scumblette" is applied by spraying over a different coloured ground, and, while wet, this is "flogged," or a dry brush is drawn over the surface, removing hair-like parts which expose the ground colour beneath. Thus a very dark green or even black may be used over a white or nearly white ground, or a very dark red over an orange chrome ground. Various metallic effects may also be produced on wood or other materials by using silver, aluminium, gold or copper leaf, and partly spraying over it a lacquer of suitable colour.

The actual graining can be done in the ordinary way by an expert artisan, but as a rule this would be too costly when perhaps thousands of iron or other goods are to be turned out in a short time. In such a case transfer graining paper is sometimes employed, but this also is somewhat costly. Bellamy's graining rollers are found to be very economical. This tool consists of a cylinder on the outside of which is engraved the grain of various woods, such as oak, mahogany, maple, satin wood, birch, walnut and ash. All that is necessary in working it, is to pass the roller over the surface immediately after the graining colour has been applied, when it will be found to remove some of the paint and give the appearance of graining. This appearance is considerably enhanced if the parts are softened after the roller is used by going over the work with a badger softener.

Marble Grounds.

For the convenience of those who are called upon to imitate marble for any class of work, the following information is given as to the colours to be employed for the ground colours.

White.—A dead white ground should be used mixed to dry hard and smooth.

Sienna.—White blended with a mixture of white and raw sienna in irregular patches.

Pink Marble.—The ground may be the same as that used for sienna, but a little Venetian red should be added to give it a pinkish cast.

Alabaster.—Light cream ground made by adding a little middle chrome and vermilion to white.

Rouge Grotte.—This is a very beautiful marble which contains a large number of different colours. The ground may be either white or Venetian red, mixed with a little chrome yellow.

Granite.—There are several varieties of granite, the principal being termed "grey" and "red" respectively. To mix the former ground, add a little black and Prussian blue with just a touch of Indian red to white. The grounds for red granites can be produced by mixing Venetian red and white.

Rouge Royal.—A mixture of Indian red, Venetian red and vegetable black, with a little white, will make the correct colour for the ground of this beautiful marble. It is very necessary that the ground be quite "solid," and to produce this, two, or even three, coats may be necessary.

Egyptian Green.—The ground should be a dead black.

Verd Antique.—The same as above.

Devonshire Marble.—Venetian red and ochre with a little white to produce a light terra-cotta ground.

Black and Gold.—A dead black ground should be used.

Dove.—In this case a white ground without gloss may be employed, but a grey is better, such as that produced by tinting white with Prussian blue, a little black and a very little Indian red.

Grey.—The same as "dove."

St. Anne's—A dead black ground should be used.

Graining Grounds.

Pollard Oak.—The ground colour is prepared with a mixture of Oxford ochre, Venetian red and white lead in proportions, to form a rich buff; or white lead, chrome yellow and vermilion may be used.

Knotted or Root of Oak.—This ground is exactly the same as the above.

Birch.—The ground is prepared with white lead, a little Oxford ochre and a little Venetian red, of which latter, however, only sufficient must be used to make a very light buff colour.

Mahogany.—The ground colour is prepared with the best Venetian red, yellow ochre and a little white lead (or orange chrome may be substituted for the yellow ochre). If it is desired to increase the brilliancy of the colour, substitute vermilion for Indian red. If a light ground is required use the same colours as above, adding more white. The addition of a little vermilion will increase the richness of the colour.

Rosewood.—The ground colour is mixed in the same manner as above described for mahogany, but a little burnt Turkey umber and Victoria lake is added.

Satinwood.—A little Oxford ochre added to white lead gives the proper ground for this wood.