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56 BODY MANUAL
Keep the torch moving around in a rotary motion to heat
evenly. As the spot is heated, it will rise in a peak.
FIGURE 81
Upset the metal in the peak by striking the heated area a
sharp blow with a mallet or broad face hammer. Use a
dolly block to back up the hammer blows. The heated
area is soft and pliable, and the force of the blows will
center themselves on the heated area only. The surround-
ing areas, being cool and rigid will hold the heated area
within its limits and any excess metal will pile up in the
heated, softened area. The result is a compressing of the
metal within the heated area.
FIGURE 82
After upsetting the peak, soak a sponge in cold water and
apply to the heated spot. The cold water coming in con-
tact with the heated metal causes a quick contraction.
CAUTION: DO NOT WATER QUENCH THE
METAL WHILE IT IS RED HOT, WAIT UNTIL IT
HAS TURNED BLACK.
FIGURE 83
After water quenching, the remaining irregularities in the
shrunken area are smoothed out by bumping with a body
hammer and dolly block, Figure 83.
FIGURE 84
Where a large excess of metal exists, the first shrinking
operation may flatten the center of the hump, leaving an
outer ridge. In this event, the excess metal remaining is
given the same heating, hammering, and quenching oper-
ation as was used in the beginning, Figure 84.
FIGURE 85
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