Reproducing A Design

Make a template of heavy paper, as in Fig. 5-9, and use this to shield the portions of the aluminum surface which you wish to remain hright. Scruh the exposed surfaces with steel wool, sandpaper, emery cloth, crocus cloth, or other ahrasive as in Fig. 5-10.

Embossing A Design

Lay out design full scale on paper, and trace through onto the aluminum, using carbon paper and sharp pencil. Then emboss it into the surface with a nail punch, as in Fig. 5—11, or use a screwdriver, nail, or other tool as in Fig. 5-12. Back up with scrap wood. Possibilities are limited only by your ingenuity.

Three-Dimensional Designs

To produce a raised, embossed, or three-dimensional design, carve a pattern into a block of hardwood 1" or more in thickness as in Fig. 5-13. Place the sheet of aluminum over the carved area, cover with an old rubber inner tube, and hammer heavily. If pattern is small, use a ball peen hammer.

The embossing can be reproduced many times without damaging the wood block. Any number of small rosettes (Fig. 5-13) can be made this way and cut out with scissors after forming.

Antique Effects

Embossed sheet with leather grain pattern or peened or other mechanically worked sheet surfaces take a beautiful "antique" finish as follows: Select the color of paint, enamel, or lacquer desired, and apply it to the face or "front" (concave embossed) side of the sheet. When thoroughly dry, highlight by rubbing lightly with steel wool to remove paint on raised portion of the pattern, leaving it in the low spots.

This produces novel and attractive effects. It allows carrying out any desired color scheme to make the aluminum "match" its surroundings.

Another novel effect is produced by reversing the embossed sheet and applying paint to the "back" (convex or raised side) of the pattern. When coating is dry, highlight with 4/0 or 5/0 sandpaper wrapped around a block of wood. This flat sanding bares only the highly raised portions of the embossed pattern, leaving a larger area of painted metal than the first method.

For Bar, either %" or 1", strokes from the ball end of a ball pcen hammer will produce an antique or wrought-iron effect when subsequently roughened with fine sandpaper or garnet paper and painted black.

To give any aluminum object a "wrought-iron" appearance, soot it thoroughly over a candle flame and hammer the soot into the surface, using steel hack-up plate. Then clean off loose material with cloth or steel wool.

Avoid Corrosion

Where other metals contact aluminum for extended periods with moisture present, electrogalvanic attack may result. Thus where it is necessary to use conventional iron hardware, such as hinges or flat corner braces, apply a coat of paint, enamel, or lacquer to the hardware first before fastening it to the aluminum. Aluminum paint is ideal for this purpose.

Fig. 5-14.

Indoors, where everything is kept dry, pay no attention to this factor. This means that steel nails, screws, bolts, and other items can be used with aluminum parts without corrosive action resulting as long as the assembly is not wet or moist for any considerable period of time.

Ground Contact over long periods may cause corrosion of aluminum surfaces, depending upon how much moisture and free alkali is in the soil. To guard against possible corrosive attack here, all aluminum in continuous contact with the earth, such as in a trellis, garden markers, and decorative borders for flower gardens, should be protected by applying one or two coats of aluminum paint to those areas to be covered with earth.

Bituminous paint also provides excellent protection. Zinc chromate, too, is a good corrosion inhibitor.

Chemical Etching

A chemically etched surface has a soft, dull appearance which contrasts well with bright polished surfaces. So objects to be decorated by etching should be first highly polished. Sources of specially polished sheet in form of circles for trays will be found in Chap. 15.

Transfer pattern to the sheet surface with carbon paper and pencil. Cover areas to remain bright and shiny by painting with "T" asphaltum paint, black stove polish, or bituminous paint. Use two coats if necessary. A fine-tipped brush will help to reproduce design details accurately. Then fill in large areas with a heavier brush (see Fig. 5-14).

Fig. 5-15.

Etch with a 50-50 mixture of muriatic acid and water. Always pour the acid into the water. Mix and store only in glass or crockery. Use a strong lye solution if acid is not available. Always wear rubber gloves and apron. Avoid any contact with skin or clothes; rinse and flush off with large amounts of water if an accident occurs.

A porcelain enameled tray (Fig. 5-25) or kitchen pan works well. For least amount of solution, place the aluminum part to be etched over a piece of heavy-duty aluminum foil and turn up foil edges all around to confine solution. Cover the aluminum surface with the etching solution. Pour the solution off after "boiling" stops 15 to 60 minutes. For a deeper etch, repeat the process.

After etching, rinse thoroughly with water. Remove blocking with a soft cloth soaked in turpentine, benzine, or kerosene. Be careful to avoid scratching the highly polished areas. Repolish with 000 steel wool and powdered pumice.