Finish the cleaning by scrubbing
with turpentine and a brush having stiff bristles.
If the metal is first covered with turpentine and then heated over
a flame, all the colors of the rainbow will appear on its surface.
These colors fade away in the course of a long time, but they can
be easily revived. Another way to get these colors is to heat the
metal and then plunge it into the acid bath quickly.
A green finish is obtained by painting the background with an acid
stain composed as follows: 1 part ammonia muriate; 3 parts ammonia
carbonate; 24 parts water. If one coat does not give the depth of
color desired, repeat as many times as is necessary, allowing each
coat time to dry before applying the next.
To "fix" this color so that it will not rub off, and to keep the
metal from tarnishing, apply a coat of banana oil or lacquer.
Thermometers of suitable size can be bought in either brass or
nickel. They have holes through their top and bottom ends through
which metal paper fasteners can be inserted, and these in turn put
through holes punched in the copper back.
** To Make an Electric Piano [247]
Make or buy a table, about 3 ft.
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