Painting by Immersion and by Compressed Air: A Practical Handbook

Picture frames are also finished in black having a semi-gloss finish,which gives an excellent effect and is most durable.

It is very important in this class of work that ample ventilation be given to the apartment in which the work is done in such a way as to avoid draught. Heated air, of course, takes up moisture much more readily than cold air, and unless means are provided for adequate ventilation the air will become moisture charged, and the work will thereby be adversely affected. This is a point which is frequently overlooked.

Spraying Ships' Hulls.

It is the opinion of the author that the painting of ships' hulls may be done by means of spraying with a great saving of time. Although there are no available statistics, it is probable that many thousands of acres of surface on ships' bottoms are re-painted every year. A careful enquiry has shown that some experiments have been made in this direction, but that they have always been of a somewhat perfunctory character. The very large surface gives an opportunity for the use of the spray which is almost unequalled in its possibilities. There are, however, certain difficulties in connection with this work, which have doubtless had much to do with the fact that it has not, thus far, been adopted to any considerable extent.

The first of these is that the composition applied is not ordinary paint, but one which is mixed with arsenic, mercury and other poisonous compounds, which are added in order to destroy animal and vegetable life and prevent the adhesion of barnacles and other marine growth. So necessary is this that compositions are made suitable for different waters through which the vessel must pass, and it is well known that those vessels which sail by regular routes need much less frequent painting than a tramp steamer which may sail in any direction and through any sea. The reason is, that in the first case the composition is specially made to withstand the growth of life in well-defined waters, while in the case of tramp steamers it must be more or less of a general nature.

The point, however, which has now to be dealt with, is that the addition of arsenic, etc., added to the paint, causes it sometimes to settle out, but it is suggested that this could be easily overcome by an agitating apparatus in the paint pot. As explained elsewhere, such an apparatus is frequently used in ordinary painting, when the composition of the paint demands it.

The second and more serious objection to spraying ships' hulls is that the work must be done in the open, and that the wind will carry away a portion of the paint and prevent it reaching the surface required. It is suggested, however, this might perhaps be overcome by adopting a form of enclosed cabinet, which would screen the operator from the wind. This could be rendered portable by being mounted on a platform with wheels, and a system of elevators, and be adopted with a little ingenuity to reach the higher parts of the vessel. In any case, the subject is one which is well worth the attention of those interested in spraying, owing to the immense field it opens up.

In this connection attention may be directed to the illustrations which appear on pages 252 to 254 of the apparatus used for spraying by the Pennsylvania Railroad for painting their freight cars. This apparatus may be adapted, with suitable modifications, for ship painting also.

Slate Enamelling.

The usual procedure followed in connection with enamelling on slate for mantel-pieces, stall-board, signs and other work of the kind, is to get the slate slabs quite smooth and level by means of a slate planing machine. A coat of "black varnish" or enamel is then sprayed on, and is stoved at 160° to 170° F. Careful rubbing down with powdered pumice and water is next done, when the work receives a second coat of enamel. It is again stoved and then rubbed down by hand to a finish with rottenstone and oil. Sometimes, the slate receives three coats, the finish being left with a high gloss, but more frequently the semi-gloss obtained by rubbing with rottenstone is preferred. It is unsafe to stove slate at higher than 260° F., as it is likely to break when cooling.

Formerly, a great deal of this class of work was done in imitation of various marbles, mostly worked on a black ground, but "marbling" is now done but rarely. The method is to employ a shallow tank of water upon which are placed colours in imitation of the veins of the marble to be imitated. This colour is of a special kind, made to float, and is manipulated on the surface. The slab of slate, which has received one coat, is then dipped gently in the water, when the colour adheres to it. A coat of stoving varnish completes the operation.

Many slate enamellers still employ the old method of applying the enamel by means of brushes, but it is only a question of time before compressed air will be used almost exclusively, for the reason so frequently urged in this work, viz., that the spray eliminates brush marks and, therefore, greatly reduces the work of rubbing down.

Spraying Colour Specimens.

Specimens of various colours in distemper, oil, varnish and enamel are sent out in very large quantities by the various manufacturers of those goods, and the preparation of these specimens may be very considerably facilitated by using a suitable spraying machine. When distemper is used fairly large sheets of paper are usually employed, and these are cut up by means of a guillotine machine when dry. Ordinary oil paint and varnish paints may in like manner be sprayed, but when an enamel finish is desired it is usual to apply the paint on the back of a sheet of thin white celluloid, which gives the appearance which would be obtained by the application of varnish. In spraying celluloid sheets it will be found that after a little practice the paint may be laid on much more uniformly than is possible by means of a brush. This can easily be demonstrated by holding up the painted sheet to the light, when it will be found that the paint applied by a brush shows more inequalities or streaks than that when sprayed.

Stencilling may be done very well on either paper or celluloid sheets; in the case of these specimens, for example, supposing it was desired that each specimen of colour when cut up should bear a number, it would not be difficult to cut a stencil in zinc or leadfoil, repeating the number as many times as there are specimens to be cut out of each sheet. The tinfoil would then be fixed in position and the spraying done over it, which would mark each piece with a number. Then the coat of colour can be sprayed all over the surface. The plan above would be followed in the case of celluloid, but when ordinary paper is used the process would, of course, have to be reversed and the number put on last.

In some cases where a very great brilliancy of colour is required, this is done by the process of glazing, which is described elsewhere in this book; for example, a comparatively dull red could be very much brightened by spraying a coat of madder or crimson lake. Here, again, if celluloid is used the glazing colour will go on first and the ground colour afterwards, but in ordinary circumstances the ground work would, of course, be first applied.

Probably the most complete plant for preparing colour specimens is in use by Mander Brothers, the well-known paint, varnish and colour manufacturers, of Wolverhampton. The spraying of colours is mostly done on celluloid sheets, and four cabinets of the Airostyle type are in more or less constant use. These cabinets have glass sides and top hung on hinges so that they may be opened when desired. The pressure of air is usually from 30 to 35 lbs., with an additional 5 lbs. on the paint pot. One coat is sufficient, because, of course, it can be made as thick as may be necessary according to the particular specimens being prepared. The saving of time is estimated at, at least, 33 per cent.

In dealing with celluloid sheets it is obviously of importance to adopt some safe means of storing them while drying. Formerly Messrs. Mander Brothers had a long series of double clips by which the sheets were suspended while drying, but this method has been abandoned owing to the danger involved of fire. Now suitable tin-lined cabinets are provided having from top to bottom a series of cleats which support open wire trays. Each sheet of celluloid as it is painted is placed on a wire tray which is slipped in the cabinet, where it dries in 12 hours.

Tramcars.

As far as the author can gather information, the processes described in this book are not used in Great Britain to any extent in the finish of tramcars, but are gradually making headway in America, particularly for the final coats. There appears to be no reason, however, why "flowing-on," as described in Chapter XIII., should not be used to a much greater extent than is at present the case. The earlier coats, being very stiff, might be applied by means of brushes, and these coats could be followed by spraying, and finally the finishing coats could be flowed on.

Formerly, this work was done almost in the same way as that by which the fine finish of a carriage body is produced, viz., the building up of a perfectly smooth surface by a large number of coats, rubbing each one down carefully and finishing with two or more coats of varnish, these being also rubbed down excepting the last.

In modern practice these methods are greatly simplified, and at least several coats, which were formerly thought to be necessary, are dispensed with. The finish is often obtained by applying a coat of a suitable enamel, rubbing this down, and then giving a final finish of a good flowing varnish.

It is suggested that spraying, or flowing-on, could be used for some of this work with very great advantage in the saving of time.

In dealing with many paints which are to be stoved, a well-thought-out system should be in use of conveying the articles from the finishing rooms to the painting apparatus and thence to the ovens. If more than one coat is given it will be necessary to arrange also for conveyance after the parts are baked back to the painting plant for the next coat.

As a rule, a system of overhead runways, such as is described for use in paint dipping, will be found the most economical method to adopt.

It will be observed that in the list of trades and articles which may be successfully painted by mechanical means, given on pages 3 to 6, there are many which are omitted from the detailed descriptions. The reason for this is that the main principles are in all cases practically the same and the details must necessarily vary, not only with the goods being dealt with, but according to the extent of the operations and the accommodation of the factory available.

Thornley & Knight, Ltd., of Birmingham, specialise in this business, and have sold, during the last few years, many thousands of gallons of their air-drying coloured japans, for use on car bodies. Many of the largest motor car manufacturers have adopted the process.

CHAPTER IX.

Another interesting Airostyle plant is shown in Figs. 84, 85 and 86, and was installed for japanning gas fires, radiators, gas cookers, etc. An item worthy of note in this plant is the patented hot air apparatus installed for warming the japan and for also heating the sprayer and flexible tube conveying the japan to the sprayer; it is clearly seen in the centre of the two hoods. The large hood is mainly used for radiators, which are wheeled on to the large ball-bearing turn-table, shown white for the purpose of a clearer view, but when not so used a table is wheeled into position and two operators are accommodated for smaller work.

The power unit, consisting of electric drive and suitable overhead countershaft, together with the compressor and ball-bearing fan, is shown in Fig. 100, and is directly outside the japanning shop.

This plant was installed for the Davis Gas Stove Company, Luton, and has been in operation for several years.

The compressor shown in Fig 98 also delivers air to the gas cooker department for two or three operators, and to the porcelain enamelling department for six or seven operators, but as the same practice is adopted as is shown in the photos here reproduced, no useful purpose will be served in describing them in detail.

Undoubtedly one of the most important plants in the country, and one producing the highest finish, is installed at Messrs. Joseph Lucas, Ltd., Birmingham, and the photographs reproduced here are by their kind permission. The author was granted the privilege of inspecting the plant fully, and proposes to enlarge upon its arrangement and capacities for saving of labour, etc.

The whole of the work was carried out by Messrs. The Airostyle and Lithos, Ltd., and it must be admitted that the plants are so arranged as to admit of rapid handling of the work, and the subsequent stoving of the articles is just as conveniently provided for.

Two distinct plants are in use at the moment with a separate steel plate central draught fan and a water-cooled air compressor (the type of fan and air compressor employed is shown elsewhere in the book, see Figs. 71 and 79).

On referring to the drawings Figs. 97, 98 and 99, showing respectively an elevation, end view and plan of one of the plants, it will be seen that the plant is divided up into two bays, each accommodating six operators, so that, in all, twenty-four operators are provided for in the two plants and were actually seen at work.

It will at once be noticed that ample space between the bays is provided, and this is most essential in order to give sufficient room for the racks which are wheeled into place behind each operator. These racks are readily seen in the photographs, Figs. 103 and 106, and can also be distinguished in Fig. 104.

The japanning shop in which the plants are installed is of large dimensions, 250 feet long by 48 feet wide, and is extremely light and airy, but, owing to the fact that the roof-lights are now painted over (by Government regulations), the shop at present appears to disadvantage, and the photographs consequently suffer.

The photographs, nevertheless, show very clearly what an immense amount of work can be daily handled, but, notwithstanding this, the writer was assured that there were still numbers of brush hands in the shop. This was primarily due to the fact that full arrangements for spraying are not yet completed (12 more operators are being provided for), and, secondly, to the fact that certain work needing a large amount of masking can be almost as readily brushed, and this class of work finds employment for brush hands. Messrs. Lucas, Ltd., admit that there is a wastage of japan, but maintain that a heavier and much more even coat is applied with a superior finish to brush work, and that there is an enormous gain in time of about 4 to 1 over brushing.

They state, also, that an indirect gain is obtained in the economical working of the stoves, for these are filled far more quickly, and, consequently, the daily output per stove is correspondingly increased.

A striking proof of the saving is their statement that if they had not the system of spraying at work, it would have meant 200 hands in the japanning department, whereas they now employed only 90, and a considerable number of these were engaged upon brush work, so that if only the whole of the work could have been handled with the spray, then the number of hands necessary would have been even less than 90.

The photographs, Figs. 105 to 107, need no description, and are self-explanatory to a large extent.

The type of instrument used, and the accessories, are described in detail elsewhere, as they are the standard practice adopted with all Airostyle plants.

The writer also had the privilege of inspecting another interesting Airostyle plant, installed at Messrs. G. Cabdy and Sons, Birmingham, where 7 or 8 operators are employed upon high-class celluloid enamel finishes upon buttons, medallions, cameos, electrical fittings, and last, but not least, numerous parts for munition work, such as cartridge clips for 18 or 24-pounders, etc.

The small articles are laid on a grid measuring about 11 inches by 9 inches, and while holding the grid the operator sprays over the whole of the article on the grid, and in the case of rounded faces of buttons, sprays these obliquely from all sides in turn, as well as over the tops of the buttons.

It may be mentioned that the greater part of the spraying paints and enamels are supplied by Messrs. Thornley & Knight, Ltd., of Birmingham.

The Birmingham Small Arms Co.

The cycle department of this well-known firm deals with an enormous, amount of parts, and a new paint spraying department on an extensive scale is in course of construction at Redditch, and the method in use at the Birmingham works will be to a great extent followed. In both cases the "Midland" sprayer is used under a pressure of from 30 to 50 lbs.

The method is very thorough, and although comparitively expensive is well calculated to produce a finish which is (a) capable of withstanding hard wear and possible knocks and (b) absolutely rust-proof. The finish is elastic and very durable. It is produced by the following method. The steel or iron parts are first thoroughly washed in pure American turpentine in order to remove every trace of grease and dirt. In passing, it may be said that a suitable white spirit would probably answer as well and would effect a considerable saving, although it is possible that the pure turpentine leaves a certain residue behind it which is of advantage in forming a key to the subsequent coats. The parts are then stoved, when a coat of pure Baltic linseed oil is applied by means of brushes, and they are again stoved at 250° F. Then a coat of black japan, known in the works as "rubber solution," is sprayed on, and a third stoving is given in this case at 280° F. This is followed by two coats of khaki-coloured enamel sprayed on, which dries with a semi-gloss finish. The parts are stoved between each coat and after the final coat, so that they receive five stovings altogether.

The ovens are of special construction and are described in detail elsewhere. The japans employed are supplied by Messrs. Arthur Holden and Co., Ltd., of Birmingham.

Samples of the work thus finished were submitted to the author, who carefully tested them. He found that the finish was all that could be desired. A piece of plate metal, for instance, was bent double without the finish being affected, thus showing very clearly the great elasticity of the coating—a most important and necessary quality in a finish for this class of work.

Messrs. Fletcher, Russell & Co., Ltd.

This well-known firm use spraying at their Warrington Works on an extensive scale. All parts of gas cookers, gas stoves, and ranges large and small, are sprayed by different sizes of the Airostyle sprayer. Stoving takes place in most cases, and the work of spraying effects a great saving, one man being able to do the work of at least three under the old brush system.

Some very beautiful effects are obtained in stoves intended for use in drawing, dining and reception rooms, by spraying various coloured semi-transparent lacquers over silver-bright iron or steel. Rich reds, browns, greens and blues in various shades are produced, and the bright surface beneath the lacquer gives a very pleasing and artistic effect. Stoving produces the necessary hardness of the lacquer, which may be regarded as being very durable.

Special Machines.

The Berkel and Parnall's Slicing Machine Co., Ltd., whose extensive works are at 6, Bow Common Lane, London, E., have had a plant for paint spraying in use for the last four years, and find it to be quite successful and a great saving of time over the old method of applying the paint by means of brushes, in addition to a superior finish being obtained. The sprayer in this case is the "Invincible," and the paint is sprayed on under pressure varying according to the nature of the work. The iron parts which go to make up the slicing machine are first primed and stoved and any imperfections stopped in the usual manner. They are then painted by means of compressed air and again stoved, after which they receive a further coat, which is also stoved. Various ornamentation in gold is then put on, mostly by the transfer process, although certain parts require lining by hand. The final coat of varnish is given by means of brushes, it being found that this is the most economical way for this particular class of work. In this particular it will be observed that the method differs from that used in many other works where all the operations are done by spraying, including a final coat of varnish. The colour used for the paint is a bright red. There are two spraying cabinets with the usual exhaust, and turn-tables are employed for turning the parts round to receive the coat of paint. It may surprise some readers to learn the very large extent to which these slicing machines are used throughout the world for various purposes.

Gittings, Hills and Boothby, Limited.

The plant for spraying in use in these works is principally intended for experimental purposes in connection with the preparation of paints, varnishes and lacquers of various descriptions which the firm manufacture. An up-to-date type of pistol is used, with a pressure not exceeding 30 lbs. to the inch. The work is done in a small closet with glass sides open at one side, and a small turn-table is employed upon which to place the article that is being sprayed. Some admirable results are obtained with the aid of gold lacquers. It is found that in certain varnishes the application of heat is an advantage, but as a rule the spraying is done cold. Among the articles which have been painted are motor cars and various smaller appliances.

The Kingsbury Manufacturing Co., Ltd.

A typical plant for finishing picture frames, furniture, fancy articles such as wood, cane and other ornamental baskets, is that of the Kingsbury Manufacturing Co., Ltd., 1, Markfield Rd., Broad Lane, Tottenham, N. This firm are the inventors of what is known as the "Inolite" system of gilding, which is described as an ideal process. Certainly the work produced is as near perfection as one would desire, the gilding being excellent in appearance, while it is guaranteed for five years to be free from discoloration or tarnishing. The process consists in applying by means of spraying, first, a coat of special enamel, which when dry is rubbed down with a solvent applied by a pad. Upon this is sprayed a coat of gold paint, and a final coat of colourless celluloid varnish is given which protects the gold from tarnishing. The process adopted is described in greater detail under the head of "Picture Frame Finishing" in this book.

The coloured celluloid enamels which are applied to fancy baskets, etc., have a very attractive metallic appearance, which is far superior to the ordinary crude bronzy effect. Another speciality of the firm is the finish of frames in special black, which gives a perfectly smooth finish which might be called "egg-shell gloss." It is quite artistic in appearance, eminently suitable for the particular purpose, and gives a durable frame at a comparatively small cost.

The firm estimate the saving of time by using the spraying as compared with that of employing a brush is as 5 is to 1. They point out that a little extra material is required, but this is not begrudged as it possesses advantages in an increased durability of the protective coating.

The Gas Light and Coke Co.

Several of the works of this company, which deal with gas meters, are fitted with paint spraying installations. The branch at Laburnum Street, Kingsland Road, in charge of Mr. W. F. Fagan, may be taken as a type. Two Aerographs and three Airostyles are in use. The old meters that come to the works are examined, and if the paint is in fairly good condition the surface is rubbed down with pumice stone and water, but if it is much decayed the meters are placed in a hot bath containing a solution of lime and caustic soda, and allowed to remain in it a short time, when the paint becomes so soft as to be easily removable. The surface of new tinplate is cleaned down with spirit, when it is quite ready to receive the coat of paint. At these works many different makes of meters come in to be dealt with, hence various masks are necessary to protect those parts which it is not desired to spray. The pressure used here is rather more than usual, being 40 lbs. to the sq. inch. The time taken to paint a meter is very small, as can be understood when it is said that two men working on five-light meters can turn out 30 an hour. Before the spraying apparatus was put in, about a year ago, a man could paint with a brush about three meters in an hour, so that, with the present system, there is an immense saving. It is calculated that the whole of the original outlay of putting in the plant will be returned at the end of about a year.

The masks or shields having been placed in position, a cap is placed over each union and the paint is sprayed on. The meters are turned out at the rate of 900 to 1,500 a week of 48 hours. The spraying apparatus is provided with the usual exhaust consisting of two 9-inch holes to each cabinet, with grating over. About 10 per cent, more paint is allowed than that used when it is applied by hand, but the greater part of this goes on the surface, and the coat of paint as a protector is distinctly improved. The exhaust is carried up to the roof, but the actual loss of paint is very small.

Fig. 108 shows a general view, and a large central draught steel plate fan is employed to exhaust the hoods, and to drive this and the compressor a gas engine is employed. The compressor is of the type illustrated in Fig. 71, page 115, and can just be discerned behind the gas engine.

Fig. 109 shows a gas meter in position, with the necessary masks fixed, and Fig. 110 shows the operator about to spray-paint same. This plant has been in daily operation for more than two years.

The Gas Meter Co., Limited.

The installation of a spraying plant at the works of this firm, which are at 238, Kingsland Road, have been in operation for rather less than a year, but has proved quite satisfactory. Various types of gas meters are sprayed with one coat of Torbay paint, which is an iron oxide paint of high quality, and the one coat possesses amply sufficient quality to give a good covering. Prior to painting the surface of the tinned plate which is used for gas meters, it is cleaned down with a piece of waste dipped in spirit. Masks are used to fit over name plates, etc., and the spraying is done in the usual cabinet, with an exhaust. A three or four-light meter takes about two minutes to do, and the larger sizes, of course, longer in proportion. All sizes up to and including 500-light meters are sprayed, but those larger, up to 1,000 lights, are a little too big to handle. The greater part of the meters are done in deep red oxide iron colour, but three other colours are used in addition, as may be required. The meter to be sprayed is placed on a turn-table which bears on a sharp steel point and has on its upper portion spikes or ridges, to hold the meter in position. The Aerograph spray is employed in this case.

CHAPTER X.

In buying materials for this purpose it is well to purchase of those firms who have made a special study of the subject. The following is a list of a few such firms, all well known to the writer, and although it by no means exhausts the list yet anyone desiring to buy materials may very safely leave themselves in their hands.

Messrs. Docker, Bros., Ltd., Birmingham; Gittings, Hills and Boothby, Ltd., Tower Varnish Works, Long Acre, Birmingham; Goodlass, Wall and Co., Ltd., Seal Street, Liverpool; A. Holden and Sons, Ltd., Bradford Street, Birmingham; Indestructible Paint Co., Ltd., King's House, King Street, London, E.C.; Lewis Berger and Sons, Ltd., Homerton, London, N.; Llewellyn Rylands, Ltd., Balsall Heath Works, Birmingham; Mander Bros., Wolverhampton; Postans and Morley Brothers, Ltd, 19, Lionel Street, Birmingham; The Frederick Crane Chemical Co., Birmingham; Thornley and Knight, Birmingham; Wilkinson, Heywood and Clark, Ltd., Caledonian Works, Poplar. E.; Pinchin, Johnson and Co., Ltd., Bevis Marks, London.

The following are American firms:—

The Moller and Schumann Co., Chicago, Ill.; John Lucas and Co., Inc, Gibbsboro', N.J.; The Chicago White Lead and Oil Co., Chicago, Ill.; John W. Masury and Son, New York, N.Y.; The Glidden Varnish Company, Cleveland, O.; The Sherwin-Williams Co., Cleveland, O.;

STOVING ENAMELS.

We now reach these important enamels, and extract the following from the foreword of the little book above mentioned. Messrs. Wilkinson, Heywood and Clark claim to be the first successful makers of stoving blacks, which was in the days before the introduction of bicycles. Though originally introduced for cycle work, stoving enamel produces a most successful finish for all kinds of materials. In the United States of America such enamels are used in great quantities for finishing standardised motor bodies. These black enamels have gained a very high name for themselves, as properly baked they are extraordinarily hard, brilliant and tough, and when applied over such material as tin sheets are flexible enough to withstand being bent double without showing signs of cracking. An important feature are the coloured enamels made by the same firm, which run through a whole series of yellows, reds, browns, greens and blues, and are hard, durable and tough, and can be stoved without changing colour. We extract the following notes on the "Application of Stoving Enamels," and fully endorse the recommendations offered:—

1. All work should be perfectly free from dirt, grease or oil, before application of enamel.

2. Every trace of moisture should be removed before enamelling. This can be effected by stoving the work, previous to enamelling, at a light heat. Moisture on work will cause enamel to blister and burn.

3. Always when using brushing or dipping enamels, allow the enamel to set slightly (i.e., after the surplus paint has dried off) before putting in the baking oven. This will prevent uneven stoving and eliminate "fat edges," as far as possible.

4. Oven heat should be increased gradually. Never place enamelled work into a hot oven at once, but raise the heat by degrees, until the full temperature is obtained.

5. Most of our enamels are sent out slightly thick; should an easier working material be desired, in the case of colours or blacks, add kerosene gradually until the required consistency is obtained. Coloured enamel should always be stirred before use, to prevent the pigment settling and the light medium rising. If this is not done, the appearance of the work will lack body and appear dull and lifeless. This applies especially to dipping enamels. To render white stoving enamel thinner, add pure turpentine only, stirring well, until a uniform consistency is obtained.

6. It is quite possible to over-bake enamels and spoil the colours, and likewise under-baked enamels will not be tough enough to withstand hard wear. Particular attention should be paid to the directions on the package labels, as the various pigments require different temperatures.

7. Stoving enamels, if left in an opened can, tend to thicken considerably. For this reason, keep the can closed when not actually using the enamel.

For thinning purposes we recommend kerosene. Sp. gr. 810 at 60° F.

8. Ovens should be properly ventilated to allow the proper oxidation necessary in baking.

Enamels.

It has already been pointed out in these pages that the success of painting by dipping, spraying, "flowing on," in fact, all other mechanical means, depends upon the exact properties of the materials used. The same is true with enamels, which are made from a large variety of formulæ so as to dry slowly or quickly in the air, or when subjected to heat in a stove. The author feels he cannot do better than take as a guide to the properties of enamels in general the extremely useful handbook published by Wilkinson, Heywood and Clark, under the head of "Enamels for every Purpose." This book gives practically all the information concerning enamels likely to be required by the average user. The products are divided up under different heads, for example, one page is headed "Heat Resisting and Slow Drying Enamels." These dry fit to handle in 16 hours, and dry bone hard in 24 hours. They are made to withstand heat up to 212° F., and for this reason are suitable for enamelling iron baths, radiators, etc., particularly so as to effectively resist hot water without softening or peeling. They are made in a number of beautiful colours. A somewhat similar series of enamels is made which dry quicker, viz., in 8 hours fit to handle and quite hard in 12 hours. They are useful for touching up radiators, stoves, steam pipes, etc., and are made in white and a dozen or more colours. The next series which demands our attention are "Dipping Air Drying Enamels." They dry in 8 hours and are quite hard in 12 hours. They are claimed to produce a finish equal to that obtained by a quick air drying brushing enamel with the labour of brushing eliminated. For a finish done by immersing the article to be painted these are capital enamels, but they require to be used with a stirrer of some sort in the tank.

Hints on Stoving or Baking.

The degree of heat to which an article is subjected after being painted or japanned will obviously depend upon the kind of coating used. It is safe to assert as a general rule that the heat applied must not be higher than the particular paint or enamel is made to withstand, for, if this be exceeded, it will inevitably result in a loss of elasticity, of the protecting film and, hence, its durability.

The following hints are taken from a very useful little pamphlet issued by the Moller & Schumann Co., of Chicago, Ill. The degrees of temperature given refer to their products, and would doubtless have to be modified in some cases, according to the nature of the paint being dealt with. They will, however, form a very useful guide.

Black Japan Finishes.

One or more coats rubbing finish japan, reduced as thin as possible and still cover well.

Bake each coat at 250° to 350° for 3 to 4 hours. Sandpaper each coat lightly.

One or more coats finishing black japan reduced to brushing consistency (not too thin).

Bake each coat at 300° to 350° for 3 to 4 hours. Sandpaper each coat lightly. Rub the last coat with pumice. Apply transfer and striping to last coat of japan.

Bake these at 150° for 1 to 2 hours.

One or more coats finishing copal brushed as it comes from the can. This protects the transfer and striping and increases the depth of the finish.

Bake each coat at 175° for 2 to 3 hours. Rub each coat and polish the last coat.

If finishing copal is omitted, leave the last coat of japan in gloss, or rub and polish as preferred.

Steel Furniture Enamels.

One or more coats of first coat enamel, reduced as thin as possible and still cover well. When brushed on, use steel preservative for back and underside of metal, one coat only, baked at same time as first coat of first coat enamel.

Bake each coat at 250° for 3 hours. Sandpaper each coat lightly. One or more coats of finishing enamel.

Bake each coat at 250° for 3 hours. Sandpaper all but the last coat. Rub the last coat with pumice.

Enamels when rubbed have a different colour than the surface colour; this must be taken into account in finishing.

Transfer and striping, if any, should be put over last coat of finishing enamel. Bake at 150° for 1 to 2 hours. One or more coats of finishing copal.

Bake each coat at 175° for 2 to 3 hours. Rub each coat, and polish the last coat.

If finishing copal is omitted, leave the last coat of enamel in gloss, or rub and polish as preferred.

The same enamel will bake to different shades at different heats and varied lengths of time, so care must be observed to get uniform results.

Imitation Wood Effects.

One or more coats of ground colour; back of metal one coat steel preservative, both reduced as thin as possible, and still cover well. If the steel preservative is used by dipping, only one coat of ground colour is generally used.

Bake each coat at 250° for 3 hours. Sandpaper each coat of ground colour. One coat of graining colour, reduced with turpentine brushed on, and grained by hand, or with tools as in general graining. This may be done by machine or as transfer work.

Bake the graining colour at 200° for 2 to 3 hours. Sandpaper lightly.

Put on transfer and striping, if any, over last coat of finishing enamel.

Bake at 150° for 1 to 2 hours. One or more coats of finishing copal.

Bake each coat at 175° for 2 to 3 hours. Rub each coat. Rub and polish the last coat.

In this work, at least one coat of finishing copal is necessary to protect the graining colour.

White Work—Bedsteads, Etc.

White work cannot be finished with one coat, because no white pigment has sufficient covering power.

Two or more coats of first coat white enamel.

Bake each coat at 120° to 150° for 3 to 4 hours. Sandpaper each coat lightly.

Two or more coats of finishing white enamel.

Bake each coat at 120° to 150° for 3 to 4 hours. Sandpaper each coat lightly except the last coat.

For gloss finish, leave last coat as it is; for eggshell finish, rub the last coat.

Finishing copal is rarely used over whites because of colour.

Transparent Colour Varnishes.

These varnishes are used over smooth, clean, bright metal. As the metal shows through the varnish, no primer or filler can be used.

One coat only is applied, usually by brushing or by a coating machine; however, it may be dipped or sprayed.

Bake at 225° for 3 hours.

The more these varnishes are reduced, the lighter the colour becomes.