[Chapter VI.]
RAISED FORMS.
The first exercise in raising should be a form quite simple in outline, [Plate 34 A]. A drawing or blue print should be used showing the shape and dimensions and this should be worked to as closely as possible. Next select a piece of copper suitable in thickness for an object of this size, in this case 20 gauge. The metal for raising must be circular in shape and the diameter of the piece needed for this bowl determined in the following way:
Take a piece of string, place it on the drawing or blue print, starting in the center of the base, and follow the curve as indicated at A, on [Plate 34]. This will give the radius needed for describing the circle, which is 5-1/2". The circle is then cut out with the shears, after which another circle is described on the metal for the base. All lines made on the metal should be made quite lightly.
As a rule the copper comes from the rolling mill somewhat hardened so the next thing to do is to soften it by a process called annealing.
Place upon the annealing tray, [Figure 1], the circular piece of metal already cut, and apply the flame from the blow-pipe upon it until it becomes red hot. It is either allowed to cool off gradually or dipped in cold water and then dried in the sawdust.
Select an anvil the shape of which conforms somewhat to the outline of the bowl and also to the curve of the base. It is often necessary to use several anvils to complete an object, but a little experience will help to decide which should be used first. The No. 1 anvil on [Plate 1] seems to be about what is needed for this particular piece of work.