These are methods that are similar to each other, and also similar to techniques used in decorating leather. The process includes hitting a metal tool with a hammer, creating an impression on the metal:
Chasing makes a shallow groove or line in the face of the metal (Fig. VI-22). Chasing tools have chisel, rounded, or curved ends, with which impressions are made. A chasing tool is held vertical, guided by the last two fingers, as the other end is hit sharply with a hammer.
Embossing raises a design from the back of the metal (Fig. VI-23). A round-end tool is used to make depressions on the back of the metal, causing the design to be raised on the front.
Spotting covers the surface of the metal with closely spaced spots made by hitting the metal with a ball-peen or chasing hammer. The metal is placed on a smooth metal plate. The hammer bounces on the surface.
Tapping makes a series of closely spaced dots, usually in outlining a design (Fig. VI-24). Nails may be used as tapping tools. This method is often used with a thin metal applied to wood. Tin, copper, or brass are good media for tapping.
Tooling is a method that is similar to the method of tooling leather. The same type of design and the same tools are used (Fig. VI-25). The material to be tooled must be 30-gauge aluminum, copper, or brass foil. This may be purchased in sheets, and is easily cut with shears. The working surface may be a pad of newspaper. Modeling with the bowl of a spoon on the reverse side of the foil is sometimes used to produce large raised areas.
These are obtained by piercing or by cutting with a saw: Piercing is a method of making a design of holes in metal. It is done with nails filed in desired shapes (Fig. VI-26). It may be done from the outside of the object, leaving a smooth surface (Fig. VI-27 a), or from the inside, making a rough surface on the outside (Fig. VI-27 b). This method is used in making lanterns, to give an interesting lighting effect (see Figs. VI-45 and 46).
Cutout designs are made by cutting away the edges of metal (Fig. VI-28), or making a design cut out within a frame of the metal by saw piercing (Fig. VI-29). Chasing and embossing are sometimes used to complete the work on such designs (see Figs. VI-22 and 23).
This is done by applying a design of metal to wood, metal, or other base. The design is created by any of the methods described above, and applied by one of the fastening techniques (Fig. VI-30; see also Figs. VI-18 and 21).
This process of decorating metal uses nitric acid to eat away a portion of the metal in making the design. Nitric acid should be handled carefully. It should be stored in tightly corked bottle and kept away from other metals, as the fumes will rust iron or steel.
1. Make design and transfer to metal with pencil or carbon. Go over lines with scriber, such as phonograph needle inserted in a handle.
2. Use asphaltum varnish to paint smoothly those parts of design to be left high on the metal. Cover back and edges of article, too. Let dry. This protects part of the design not to be etched in the bath (Fig. VI-31 a).
3. Using a 3 to 1 proportion of nitric acid and water, place water in glass dish (pyrex pie plate or custard cup) and slowly add acid.
4. Place article in acid bath carefully, to avoid splashing.
5. Leave until exposed metal is covered with small bubbles.
6. Remove from bath with wooden tongs or spring clothespin (Fig. VI-31 b).
7. Rinse well in clear water.
8. Remove varnish with rags and kerosene. Surface which came in contact with the bath will be pitted; surface coated with varnish will be smooth and shiny (Fig. VI-31 c).
9. Oxidize if desired (see below). 10. Polish as desired (see below).
This is a method of making a large depression in a piece of metal, to make a bowl, plate, or tray (Fig. VI-32). A rawhide mallet and a ball-peen hammer are used with a mold hollowed out of a block or a stump, or with a "jig" to make the desired shape, or on stakes (see Figs. VI-42 and 43).
Metals must be cleaned and polished to get a good finish. When this has been obtained, the object can be sprayed or painted with lacquer to retain that finish. This is essential for objects used outdoors, as lanterns and signs. Many prefer to keep a hand-rubbed finish on copper and brass objects, however.
Oxidizing is a method of darkening part of the metal, and of polishing the high lights, to give a contrast in polish. The object is dipped in or rubbed with ammonium sulphide or liver of sulphur, which oxidizes the surface (turns it dark). It is then rubbed with powdered pumice or powder cleanser, leaving the low spots dark and the high spots brightly polished. This is used on copper, brass, nickel silver, and on metal foil designs. This method is sometimes called "antiquing."
Tin is polished by rubbing with steel wool; this should be sufficient to give a satin finish. If the article is to be used out-of-doors, it should be lacquered. A thin coating of wax will keep tin from rusting.
Copper and brass are polished with a powder cleanser, or powdered pumice.
Nickel silver is polished with powdered pumice, or a good grade of silver polish. Jeweler's rouge is also used.
Pewter is polished with kerosene and lamp black.
All need to be rubbed briskly with soft flannel or felt for a high polish at the end.