In this era of practical craftsmanship there is a field for any unique art that savors of originality and which will help to beautify the home and its furnishings.
Relief etching is one of these arts, and is a very old one, having been employed by the workers on King Solomon’s temple, and perhaps in earlier historical buildings. That was before the time of chemical treatment, however, and when the beautiful effects were obtained by laborious hand-work, a modification of which is handed down in the Turkish, Russian, and Oriental hand-etched brasses and silver goods.
Modern science and chemistry have superseded the old method, and many beautiful pieces of relief etching are produced by the acid process, which is much more beautiful in some respects than the tool-work. The process is very simple, and any boy can become master of the art in a short time and at a very moderate cost.
The equipment necessary to the work will be a tray for the acid bath, a small can of asphaltum varnish, three or four camel’s-hair brushes of assorted sizes, a bottle of nitric acid, and some pieces of sheet brass or copper less than one-eighth of an inch in thickness.
For the acid bath a photographer’s porcelain or hard-rubber developing-tray will be just the thing, but if not available a good pine or white-wood tray can be made with sides two inches high.
To protect the wood from the action of the acid, the tray should be treated to several successive coats of asphaltum varnish—one each day until the wood is thoroughly coated and the joints well filled. The wood should be half or three-quarters of an inch thick, and screws should be used at the joints and laps. A tray of this description can be made at home, and when finished it should appear as shown in Fig. 1. If the varnish is too thick when applying it, a little turpentine will thin it properly.
Small, flat subjects are best to begin with, such as hinge-plates, panels, escutcheons, or tablets. For a drawer panel, Fig. 2 shows an attractive and simple design that may be drawn on the metal with pen and ink. If the ink creeps, the surface of the metal may be roughened slightly with fine emery cloth.
With the asphaltum varnish the design is then filled in so it will appear as shown in Fig. 3 and allowed to dry, when, as a precautionary measure, another coat should be given over the blackened surface, to avoid the possibility of the acid biting through the thin places, or where the varnish has missed the metal. The back and edge of the metal is coated also, to prevent the acid from eating into it.
All the surfaces of the metal not covered with the varnish will be eaten or etched away and left with a granular surface resembling fine sand-paper, while the painted or protected parts will be left intact and with a smooth surface like the original face of the plate, as shown in Fig. 4.
The Technique of the Process
With an old woollen cloth dipped in turpentine, the surface of the plate may be rubbed, after first washing off the acid. The black removed from the ornament will tint the granulated surface of the background and lend relief to the bright surface of the ornament.
Almost any objects in metal, such as door-hinges, knobs, fireplace hoods, name-plates, vases, candlesticks, panels, and tablets, can be decorated by this process, and if artistically done the results will be very effective.
Sheet brass and copper may be purchased at large hardware stores or supply houses for thirty cents a pound, and the sheets or panels can be cut there with the shears to the exact size required. For the average work, metal not more than one-sixteenth of an inch thick will be found easy to handle; but for large panels or name-plate, pieces about one-eighth of an inch thick are preferable.
If the design shown in Figs. 2, 3, and 4 is too elaborate for the beginners, some simple outline may be drawn, perhaps a flower design, copied from some piece of embroidery work, or a figure design from a wall-paper, carpet, or dress-goods pattern. The metal should be left to dry for at least an hour after being painted with the varnish before it is placed in the acid bath.
The etching is done by placing the plate, face up, on the bottom of the tray and covering it with acid. The ground-work or unpainted portions of the metal may be bitten to any depth, but it is not desirable to cut away too much, as it weakens the plate and cuts under the ornament, unless it is carefully stopped out all around the edges of the design; and that is too much of an undertaking for the young craftsman, since it requires a great deal of time and careful work.
Fig. 1.
Fig. 2. THE DRAWING
Fig. 3. THE PAINTING
Fig. 4. THE ETCHING
Fig. 5.
A little practice will determine just when the plate should be removed from the solution, either for examination or final cleaning. Soft brass or copper corrodes much faster than hard metal, which takes about three times longer, and the process of corrosion will require from twenty minutes to an hour, according to the temper of the metal and the strength of the acid solution.
The Acid Solution
To prepare the acid solution obtain a large, clear glass bottle and fill it quarter full of pure water; into this slowly pour an equal quantity of nitric acid, taking great care not to spill any of the acid, as it acts instantly and will eat a hole in any cloth it falls upon or spatters over. Wear old clothes and a canvas apron when mixing or handling the acid, and never be in a hurry to get results quickly by the reckless use of the biting fluid. If perchance the acid should touch the clothing, apply a few drops of ammonia to the spot immediately, to neutralize the acid and stop its action. The spot should then be sponged with clear water and no stain will be perceptible.
As the acid is added to the water (never add the water to the acid), shake it occasionally to thoroughly mix it, and let the mixture stand for a while to cool; then place a rubber cork in the bottle, label it Nitric Acid Solution—POISON, and place it beyond the reach of small children.
A solution that has been used should be poured from the tray into another bottle, to be used again by adding a small quantity of fresh solution. An old solution does not act as quickly as a new one, but for soft metal plates it is preferable, as it does not require such careful watching. The fumes of the acid, when at work, are disagreeable, so if possible it is well to carry out this part of the process in the open air. After the plate is immersed in the acid, do not handle it with the unprotected fingers.
Rubber gloves may be used for this purpose, but if a pair cannot be had the plate may be raised from the tray bottom by means of a small, sharp-pointed stick, and it should then be grasped with a pair of pliers and immersed in water to stop the action of the acid. A plate may be repeatedly removed from the bath to watch the progress of the etching, but in doing so it must be handled with care, in the manner just described.
When the ground is etched deep enough, remove the plate from the acid and give it a thorough washing in clean water; then with a soft cloth dipped in turpentine rub off the entire surface of the plate. The turpentine will dissolve the varnish and leave a film of it on the granular surface of the metal eaten by the acid. As a result, the ground will be darkened or oxidized, while the parts originally protected by the varnish will be bright and smooth. The high parts can be brightened still more with metal polish, or they may be buffed and lacquered by a metal finisher.
Some Typical Designs
In Fig. 5 the face of a door-knob is shown in its etched state, the pattern being drawn in varnish, as described.
In Fig. 6 the side of the knob in Fig. 5 is shown; that is, if it should have such a flat band all around. Plain brass knobs may be purchased at a hardware store, and if they are lacquered the coating should be removed with alcohol before the etching is done, as otherwise the acid would not eat through the lacquer for some time.
For an acid bath in which an object this shape is to be etched, a yellow earthenware bowl may be used, or a low jar with a wide neck will answer very well. The knob should be suspended in the acid by means of a piece of waxed string tied about the shank.
Hinges on cabinet doors may be greatly improved by making brass straps for them, which should be applied to the wood so that they fit closely against the sides of the hinges.
Fig. 6. Fig. 7. Fig. 8. Fig. 9.
Designs for hinge-straps are shown in Figs. 7 and 8, and Fig. 9 is a brass vase on the outside of which a floral design has been etched.
Another design for the face of an oval brass door-knob is shown in Fig. 10. This is a simple pattern to draw on a knob with asphaltum varnish, and its plain but bold ornament is quite as pleasing to the eye as a more intricate pattern would be.
A design for a short, high hinge-plate is shown at Fig. 11, and at Fig. 12 a long, narrow hinge-plate or hasp-strap is depicted. Many other shapes of hasps and the patterns to ornament them may be designed by the boy with some artistic ability, and he may be able to improve upon these suggestions.
Fig. 10. Fig. 11. Fig. 12. Fig. 13.
When making hinge-straps, escutcheons, or any articles from brass plates or flat brass and copper, the edges should be shaped with a cold-chisel and mallet on the upturned face of an old flat-iron. The uneven or ragged edges may be trimmed off with a file and finished with emery cloth.
An idea for a name-plate is shown in Fig. 13. This is seven inches long and three inches wide. It is appropriate for a front door or the door of a boy’s room, changing the name, of course, to that of the proper person.
At the left of the drawing the finished plate is shown, while at the other side the blackened letters and marginal line is depicted, illustrating how the plate will look before it is etched. Or this last may be the appearance of the plate after it is etched and before the varnish has been removed with turpentine and a cloth.