The making of the
Martin Bowl
by Fred Zweig, metalsmith
January, 2004 - 2017
page 1
I begin by finding the center of the disc I am going to use and marking it with a center punch. This is known as the "kernel" and is used to mark out concentric circles that are used as guides during the raising process. The kernel is made on what will be the outside of the bowl. I then scribe and cut a 15.5" diameter disc of 18 gauge copper and file the edges smooth. The disk is then placed on a pan of pumice to anneal it for forming.
The first steps require that I do some hammering on the inside of the bowl. This hammering gives the disk a concave shape and helps the disc from distorting during the raising process.
Using the kernel as the center of the circle concentric lines are marked with a pencil compass. The first circle is drawn with about a 2.5" radius and the rest of the circles are drawn approx 1" apart. The raising begins by placing the concave disk over a metal stake with the kernel facing up. The hammer blows are now going to be struck only on the outside of the bowl. The disk is placed over a metal stake so that the bowl touches the stake just at the 2.5" pencil line. The hammer begins it's blows just above that line and forces the metal down toward the stake. The disk is held at approximately 15 degree angle to begin the raising process. The bowl is slightly turned counter clockwise each time the metal is forced down and the hammer now strikes a new point on the bowl.
The image above shows the line drawn as a guide to indicate where I begin and complete each new course of raising. I have already completed the first course and am beginning the next. This time I am turning the bowl clockwise as I raise it. I change the direction so as not to create an internal spiral stress in the bowl. I am constantly trying to maintain even blows with the hammer so as not to thin out the metal as I raise it. The purpose of the initial raising is to coax the metal into shape and not stretch it. The raising of the subsequent courses will change the angle of the sides of the bowl to conform to the angle that you have tilted the metal on the stake.
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