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Chapter 8 Nonstructural Panel Repair
the putty has cured, the filler is sanded with 180-grit sand-
paper. To prevent problems, use high-quality filler. Mix it
properly and observe the recommended cure times.
Using Lead Filler
Lead filler was commonly used to repair dents in
vehicles before the invention of body filler. It still has a
place in body repair. Some technicians use lead filler on a
repaired panel edge, such as the edge of a quarter panel
adjacent to a door. The lead filler is less likely to chip off if
the panel edge is hit. Lead filler is supplied in sticks. The
sticks have a lead/tin ratio of 70/30 or 60/40. The 70/30
sticks are more expensive, but they are easier to apply.
The key to applying lead is learning to control the
heat used to soften the lead stick. Lead that is heated too
much will melt and run off the panel, rendering it useless.
Heat the lead stick just enough to soften it, but not enough
to melt it. The lead stick will change from a dull silver
color to a bright and shiny silver as it melts. Avoid heating
the lead stick to the shiny stage. As with body filler, do not
try to fill areas deeper than 1/8" with lead, as this simply
saves on the cost of materials. Lead filler application is
easier on a horizontal surface than a vertical surface. On
a vertical surface, gravity is constantly trying to pull the
softened lead filler down and out of the fill area.
W A R N I N G
Lead is a toxic substance. Wear gloves when
handling lead products. When melting lead, work in
a well-ventilated area and wear approved respiratory
protective equipment to prevent inhalation of lead dust
or vapors. Wash your hands thoroughly after handling
lead or working in a lead-contaminated area.
There are five distinct steps in lead filler application:
Stripping.
Tinning.
Heating.
Applying.
Smoothing.
Refer to Figure 8-63 as you read through the
following explanation.
To begin the lead filling process, remove the paint from
the panel surrounding the area to be filled. The paint must
be removed from the entire area to be heated. An area at
least 5-6 times the size of the fill area will be heated.
The fill area must be prepared before the lead is
applied. This process is called tinning. During tinning, a
liquid flux is applied to the fill area. The flux cleans the
bare metal and prepares it for the application of lead.
Figure 8-63A shows a brush being used to apply flux
to a small fill area. After the flux is applied, the fill area
and the entire bare metal area are gradually heated. A
propane torch or an oxyacetylene torch with a special
tip that burns only acetylene must be used to heat the
metal. The metal is heated enough that the lead stick
softens and adheres to the panel when touched to the
heated metal. See Figure 8-63B. If the metal is too hot,
the lead will melt and run off the panel. Use steel wool or
a rag to wipe the excess lead off the fill area.
After tinning the repair area, the filler can be applied.
Two things must happen during the application step. The
bare metal and fill areas must be kept hot, but not hot
enough to melt off the lead in the tinned area. At the same
time, the lead stick must be heated enough to soften it.
Hold the torch at an angle so it can heat both the lead stick
and the fill area as the lead is applied to the panel. Lay out
enough softened lead to overfill the fill area, Figure 8-63C.
After applying the lead, the repair must be smoothed.
During this step, the lead filler on the panel is softened
with heat. The softened lead filler is then spread out and
smoothed with a wooden paddle. See Figure 8-63D. The
face of the paddle is coated with a layer of tallow or paddle
lubricant to prevent the lead from sticking to the paddle. To
coat the paddle with tallow, heat the face of the paddle with
the torch and touch the face of the paddle to the surface of
the tallow. The hot paddle face will melt the tallow.
Once the lead filler cools, it can be filed in the same
way as filing high areas when metal finishing. The lead
can be finished by block sanding in the same way as
body filler. Reapplication of lead filler is not recommended
because the existing lead on the panel will need to be
heated and may melt off unless extreme care is taken.
Lead filler can be covered with body filler, if needed.
W A R N I N G
The lead dust created when filing and sanding can be
hazardous to your health. Always wear an approved
respirator when working with lead products.
Pinholes
Scratches
Figure 8-62. This cured body filler has numerous
pinholes and scratches.