Here are the tools and the material that we need to make our first
piece of work:
_Material:_ 1 Sheet of copper, 20 gauge. Powdered pumice stone.
_Tools:_ Hard wood block, dividers, shears, round headed hammer,
planishing hammer, round top stake, mallet, files.
[Illustration]
_Directions:_ Take the sheet of copper, and with the dividers mark on
the copper a circle having a diameter a little longer than the contour
of your bowl design. Cut this circle out with your shears.
With the round headed hammer, using the rounded end, beat the metal
disc into the hollow of the wooden block until it takes on a fairly
even bowl shape. Keep turning the metal with the left hand while you
hammer it with the right.
[Illustration: Wood block]
You soon have a rough shaped bowl full of bumps and wrinkles around the
outer edge.
[Illustration: The long even buckles are easily hammered out; the
short, sharp ones are the kind that cause the cracks]
[Illustration]
These wrinkles must come because the circumference of the metal disc
decreases as it takes on the bowl shape. So long as these wrinkles are
long regular curves, they will work out all right. If they should take
short, sharp shapes there is danger of the metal splitting. In order to
avoid this be sure to keep the wrinkles hammered out flat as you work
along.
[Illustration: Smoothing surface of bowl with the planishing hammer]
If you went on hammering too long after your bowl is shaped, the bowl
would crack or perhaps break, for hammering leaves copper hard and
springy. So you must soften it before you can safely hammer any more.
To do this I hold the bowl over a gas range until it is red all over,
then I plunge it into cold water. This heating to soften up the copper
is called annealing. Repeat the hammering until the bowl takes on the
shape of the design.
[Illustration]
[Illustration: In this way one can get the shape desired]
Now take your round top stake and put it into the vise. Place the
bowl over the round top stake, and with the planishing hammer, beat
the surface until it is perfectly smooth, driving the metal just hard
enough to flatten the bumps made by the hammering in the wooden block.
If carefully done the surface will be true and bright and covered over
with brilliant facets. A skillful hammer-man can really drive the metal
in any direction he may wish. In this way you make a bowl out of one
piece of copper. The top of the bowl will be ragged. Cut this rough
edge with a pair of shears. File the top with a smooth file until it
is perfectly true. A good test to make sure of this is to lay the bowl
down on a plate of glass, or hold it up against the window pane. If
there are still any tiny openings left in the edge the light will be
easily seen through them. More filing must be done until no light comes
through from the smallest space. This done, take a piece of emery cloth
and rub the edge of the bowl until the file marks disappear. If you lap
the cloth over the edge your rubbing will leave a rounded edge, which
is just the finish it should have.
[Illustration: Trimming off the top of the bowl]
[Illustration: Marking the edge of the bowl]
_To flatten the bottom of a bowl:_ Turn the bowl upside down on a
bench. With a pair of dividers find the centre of the bottom of the
bowl. This is done by placing one leg of the dividers against the side
of the bowl and with the other making a light scratch as near the
centre as you can. Change the position of the dividers to the opposite
side and do the same, but be careful that the scratch is light. Repeat
this until you have done it on the four sides.
Where these lines cross is the centre. With one leg of the dividers on
the centre draw a circle having a diameter of about two inches. Take a
wooden mallet and strike down on the centre of the circle. This will
flatten the bottom. Work from both sides of the circle and keep the
rounding edge just touching the circle made by the dividers. If the
strokes are too heavy the bottom will bend in like the dotted lines in
the sketch.
[Illustration: Flatten the bottom]
In that case, turn the bowl up and hammer from the inside. The bowl is
now ready for polishing. Mix some powdered pumice stone with water.
With a woollen cloth that has been wet and then dipped into the
mixture, rub the bowl. This both cleans and polishes and at the same
time gives a beautiful lustre to the surface of the metal.