Tilt the tray back on the block until the edge is raised about ⅟₁₆ inch up from the surface of the block, the line still resting directly over the edge of the block.
Using the Forming Mallet.—Take up the special forming mallet and use the rounded end to start hammering the tin down to the block, still keeping the tray tilted as indicated in [Fig. 24] b. Turn the tray around as you hammer so that the tray is slightly flanged out by the mallet blows as you turn it around on the block.
Fig. 24a.
Fig. 24b.
Be sure to hammer the tin very gently and evenly, taking care not to stretch it down more in one place than another. Tin will stand considerable stretching if handled gently and evenly, but heavy mallet blows will stretch and crack it, and it will tear if unevenly stretched.
Never raise the edge of the tray away from the block more than ⅟₁₆ of an inch, but always tilt the tray back a little more each time you hammer entirely around it. The tin will quickly flange out and after having hammered entirely around the tray three or four times, the rim should flange out to about the angle indicated in [Fig. 25], No. III.
