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FIGURE 77
depressions a soldering iron will perform best, Figure 77.
Before painting a surface that has been solder filled,
neutralize any traces of acid flux by washing with a
solution of baking soda and water.
COLD SHRINKING:
Whenever ridges or humps cannot be flattened by bump-
ing or dinging, a method of cold shrinking may be used.
Cold shrinking consists of driving a high spot down,
Figure 78, and filling the depression with solder. If the
area to be shrunk is large, a series of "V" grooves may be
hammered into the panel and filled with solder.
This method is often used to smooth a welded seam. The
weld is backed up with a grooved dolly or block, and the
seam is hammered until it is just below the original
contour. The resulting groove is then solder filled.
FIGURE 78
FIGURE 79
HEAT SHRINKING
Excess metal may accumulate in a hump, Figure 79, after
the bumping and dinging operations. The hump will be
firmly bound in at its base by the circle of reshaped metal
that surrounds it. Such excess metal
FIGURE 80
should be kept to a minimum by constant reference to the
original contour of the metal adjacent to the damaged area
while bumping and dinging. Metal stretched by excessive
bumping and dinging is just as difficult to reduce as a
metal stretched in a collision. To reduce this excess metal,
a system of heat shrinking may be used. Using a No. 2 or
3 sheet metal tip on an acetylene torch, heat to a cherry red
a spot no larger than 5/8" at the top of the hump.
BODY MANUAL
55
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