There are two way to do this, you can “dish” it into a bowl, or
you can “raise” it into a bowl. Raising will produce a more
pronounced shape, but is more difficult to do. Dishing on the
other hand will give a shallow bowl rather quickly. Both
techniques are cold techniques, the metal does not need to be
heated, just annealed. I don’t think I can describe raising, but
I’ll give dishhing a shot.
Dishing uses a rounded faced hammer (like the ball end of a
ballpeen) to stretch the metal into a supporting form. The form
can be a sand bag, a tree stump or other large piece of wood
formed to act as a giant dapping block (the depth of the hole
should be shallow at first, then deeper as your bowl begins to
take shape and the edge should be rounded and smooth).
The technique is as follows: start with the metal centered over
the hole and strike it with the hammer(a small dent will appear).
Then move the metal slightly and strike it again (another small
dent touching the first). Continue moving the metal, always
striking over the hole in the form, so you make your dents in a
very gentle spiral, with dents slightly overlapping their
neighbors. Do this to the entire surface, anneal, and repeat the
process until you get the depth of bowl you want.
In the end you will have a rough bowl. If you want to make it
pretty you will have to “planish” it. For this you need a ball
stake and a planishing hammer (flat face with a mirror finish).
the technique is to hold your bowl against the stake and strike
the spot where the bowl and the stake meet. this will leave a
small spot with a mirror finish. Continue by moving the metal in
a spiralling motion with a slight overlap. Always move the
metal, not the hammer. The hammer should always strike exactly
the same spot (same is true for dishing). Once you have
completed the spiral you should have a bright mirror hammered
finish(not smooth, but with little tiny flat faces, almost like
facets).
Another important thing for this kind of work is how you hold
and use the hammer. You should not be taking big, full arm
swings, but rather short sharp, very controlled blows. Your body
should be slightly angled from the work (30 to 45 degrees), your
upper arm and elbow should be kept firmly against your rib cage
so all the motion is in your elbow and forearm. You should hold
the hammer so your thumb and index finger should be placed
opposing each other on the sides of the hammer, with the
remaining fingers wrapped around the hammer (I know i sounds
awful, but it should feel very natural and comfortable). This
position give great control, but makes the hammer stick out a a
slight angle from your hand (hence the reason the body should be
angled slightly away from the work). Your arm should just move
up and down from the elbow, only the forearm in motion. One last
thing, and this is the hardest part, your grip should be relaxed
(no white knuckling). Play with it for a while and when things
start to flow and feel very smooth you are doing it right.
I hope you can understand my descriptions, but if you have
further questions contact me off list at mehodgson@aol.com
Michael