by Matt Joseph
you scrub and neutralize them out of
Some situations may require
paint adhesion.
the paddled lead, before you file it.
leading tools that are not readily
Chemicals used to kill lead
Lead filler is shaped with body
available. For example, if you need to
residues have ranged from ammonia,
files and hand-sanding devices.
90
AUTOMOTIVE BODY WOR K AN D R UST R E PAI R
F I LLI NG
While you can accomplish most
21 filing jobs with a flat body file in
After filing the repair area, it
23
a flexible holder, some jobs and areas
This specialty bull-nose body
was sanded. The first sanding
22
require file shapes different from that.
file was very helpful in getting
application was with 80-grit paper,
The side of the decklid hinge-mount
the correct taper next to the hinge-
backed by a hard-rubber pad. Note
relief required some filing with both
mount relief. Unfortunately, files like
that the area to the right has not yet
round and square files.
this are no longer manufactured.
been filled.
Never, never, try to shape lead with
sanded over it. It does this by pro-
tours by allowing you to make very
any power-sanding or power-grinding
viding hard contact points that
minor corrections to them. Once
tool. Lead can be absorbed through
guide filing and sanding.
rough filing to remove excess filler is
the pores of human skin, and
This theory places two require-
completed, fine filing creates final
ingested in saliva. It is very deadly in
ments on the use of files and board
shapes and contours.
airborne and small particulate form,
sanders. First, they must be used in
Specialty files are often helpful in
which is the form that it attains
random patterns that vary slightly in
dealing with complex shapes, particu-
when it is power sanded. If you work
position, direction, and application
larly the transition areas between dif-
with lead, be careful to avoid its
pressure with each stroke. Second,
ferent crowns. The rules for using
fumes and small particles that con-
after rough filing is completed, that
them are the same as those for flat files
tain it. Be particularly careful to
is, the basic shape that you are trying
and files, like adjustable curve files,
cover exposed skin, particularly
to achieve has been cut into the
with simple end-to-end curvatures.
arms, wrists, and hands. I also highly
filler, you must be very careful to
The proper filing motion with
recommend wearing a particulate
remove very little material with each
body files is described in Chapter 7.
face filter. The symptoms of lead poi-
successive, random stroke. If you fol-
In summary, it is a forward motion,
soning do not appear quickly, but
low this practice, you file continuous
away from you, with a lesser side-
the effects of lead poisoning are
flats, simple curves, and crowns that
sliding movement and a shift of
extremely debilitating, even fatal.
are guided by the metal under the
weight from the front of the file to
The theory behind line filing and
filler. As filler is filed off, and that
its back. This motion promotes desir-
board sanding filler is that a series of
metal appears, it guides your file into
able, continuous contours.
somewhat random motions will
cutting correct contours. For this to
Once lead filler has been filed
average the surface that you are fil-
work, the metal under the filler that
smooth, and very close to final
ing or sanding into the continuous
guides your file has to be accurate
shape, finish it with sanding
contours that are the basis for flats,
before you attempt to file it.
procedures. Never attempt sanding
simple curves, and crowns. This
Remember, filler is not meant to
with your bare fingers. If you do, you
works because lead and plastic fillers
create the shape of what you file. It is
are more likely to disrupt desirable
are softer than the metal to which
designed to do only what its name
surface configurations and put inac-
they are applied, so that metal sets
implies, to fill low areas, and to help
curate depressions into your work
the overall shape that is filed or
to reproduce exact and valid con-
than you are to improve it. Always
AUTOMOTIVE BODY WOR K AN D R UST R E PAI R
91
CHAPTE R 9
the distortion in this reflection
changes as you change the place from
which you view it, and as the crown
or curvature of the panel changes. But
if you see a sudden change, particu-
larly one in just part of the reflection,
you may be looking at an undesired
change in the panel’s contour that
was a result of your metal finishing
work to the panel or to the filler. Sud-
Specialized sanding tools, like
den changes should only occur in
24 this one, aid in sanding fine
Major shapes and contours
areas of fairly steep crown changes in
25
detail into some panel shapes. A 180-
were fine tuned with a board
the panel. Make sure that they occur
grit paper was used to sand detail
sander fitted with 180-grit abrasive
only where they belong.
into the side of the hinge-mount relief
paper. The general contour of the
After a panel is finished in deep
area. Fine abrasives cut slowly, thus
panel was blended with the hinge-
lacquer or glossy enamel, defects
helping to avoid going too deep into
mount relief area that earlier had
like the ones you can see in reflec-
lead filler.
been detail sanded.
tions stick out like warts on the
heads of bald men. When you are
back up abrasive papers with some-
sanding of as much area as I can
evaluating your filler and metal fin-
thing like a rubber pad to give them
access with a long board sander. I do
ishing work, it is important to catch
some rigidity and some consistent
this after I have filed and sanded all
defects while they can still be cor-
pressure. Such pads vary from soft
of the details that I need.
rected relatively easily.
foam to pretty hard rub
ber. Sanding
As you file and sand filled sur-
boards use fairly hard foam pads to
faces, check them visually and by
Applying Plastic Fillers
directly back abrasive papers. This
feeling them through a rag. One
helps them to average contours, and
great advantage of lead filler is that
A detailed example of a repair
to avoid gouging filler.
as it is filed and sanded, it becomes
area that was filled with plastic filler
In some situations, you may need
shiny enough to reflect light reliably.
is described in Chapter 13. What fol-
a specialized sanding tool to create a
This means that by looking at a con-
lows is a discussion of the theory of
special shape or detail. This can be
tour and changing your sight line as
and best practices for using this type
formed by anything from wrapping
you do so, you can watch reflections
of material.
abrasive paper around a tapered file, to
move across or along that contour.
Probably, you already have the
making a specialized wooden sanding
These indicate any defects in flats,
idea that I prefer lead filler to plastic
tool to sand the detail that you seek.
curves, or crowns that may still exist.
filler. Despite my preference, the
After lead is filed, you can rough
These reflections should move con-
world has gone almost entirely to
sand it with an 80-grit paper. This
sistently, and without much change
plastic fillers. Still, even if you never
gives pretty fast cutting, while avoid-
in basic distortion, until they
intend to use lead filler, you should
ing the creation of deep scratches.
encounter changes in crown.
read the first part of this chapter on
Finish the lead sanding with papers
For example, if the fluorescent
that topic—the one that you may
between 120- and 180-grit, depend-
tubes in an overhead light fixture are
have just skipped to get here—
ing on how far you want to go.
the reflection that you are tracking,
because the shaping techniques and
Whatever sequence of filing and
they will be distorted by the curva-
tools used for both types of filler are
sanding you use, it is important that
tures of the panel from which you see
very similar in many particulars.
each stage of it removes any stray
them reflected. As you move your
One great advantage of polyester
marks and scratches that are left over
head with respect to that panel, the
fillers is that they are easier and
from the previous stage of your
tubes will seem to move along it. The
faster to shape than lead fillers. On
work. I always try to do a final board
tubes will appear to be distorted, and
large jobs, they can be grated quickly
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AUTOMOTIVE BODY WOR K AN D R UST R E PAI R
F I LLI NG
Applying Plastic Fillers
Mixed filler, deposited on a steel
2
It is important to thoroughly mix the components of polyester filler
sheet, was spread with a putty
1
separately, as well as together. Tubes of hardener should be kneaded,
knife onto the fill area. It is important
and cans of filler should be stirred with a screwdriver or putty knife, depending
to work filler into base metal, to
on their size.
ensure its adhesion to that metal.
and other interlocking shapes that
lock filler to the metal surface. The
adhesion capabilities of plastic fillers
are purely mechanical, not chemical.
Abrasives in the 50- to 80-grit
range provide good tooth. Below
that range, you leave scratches that
The filler was then allowed to
are problematic because they tend to
4
The filler was then shaped onto
cure to a semi-hard state. The
promote sand scratch swelling in
3
the repair area with a flexible
time needed for this to occur varies,
paint applied over them to the metal
plastic spreader. At this point, it was
largely depending on the proportions
adjacent to your filler. Above 80-grit,
important to avoid creating air
of hardener and filler that you mix. In
metal lacks the tooth to adequately
bubbles in the filler, and to work out
this case, a timer was set for 15
bond plastic filler. I have seen people
any air that may have become
minutes, which turned out to be just
who fanatically polished filler and
trapped in it.
about right.
metal with 400-grit, or greater, abra-
sives before applying primer to
into rough shape, before they fully
tion. Those poor souls you see dri-
them. This is a bad idea because the
harden. After they cure, they can be
ving around with bare filler showing
primer will find little to grab onto in
worked with power tools like disc
on their cars’ bodies are in for a
such a metal’s surface.
sanders, DA orbital sanders, and air
world of hurt, particularly after they
The first rule of using plastic
tools with grinding burrs.
paint over that moisture-saturated
fillers is to use a good-quality mater-
With proper metal preparation,
plastic filler, and trap the basis for
ial. Some brands of filler are better
plastic fillers have excellent adhe-
future corrosion under the paint.
than
others.
Reading
product
sion. What they do not have is much
Preparing metal properly for poly-
brochures and experimenting with
ability to resist water molecules.
ester filler involves having it as clean
different materials informs you on
After you complete work with plastic
and grease-free as possible. All visible
these issues. The second rule is to
fillers, it is important to protect filled
signs of paint, rust, and flying smut
mix the components thoroughly,
areas from moisture and humidity by
should be removed from the substrate
with themselves and with each
coating
them
with
waterproof
metal. Its surface should be given
other. When mixing them with each
primer, and/or primer and top coats
good tooth to hold the filler. That
other the mixing proportions are not
that provide moisture-barrier protec-
tooth is the crags, crannies, nooks,
terribly critical, but stay within the
<
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CHAPTE R 9
After the filler had reached its
Plastic filler is filed in much the
A round, tapered file, wrapped in
5
6
7
semi-hard state, it was grated
same way as lead filler. The
80-grit abrasive paper, was used
with a cheese-grater-type file. This
same body files used for lead can be
to file detail into the hinge-mount relief
process can remove material very
used with plastic fillers, with one bonus:
area. Later, a tapered, square file,
quickly, so you have to avoid over-
There is less tendency to accidentally
wrapped in abrasive paper, was used
enthusiastic grating at this stage.
file lateral grooves into plastic filler.
to further refine the shape of this area.
common. With lead, such additions
more. When combined in the correct
are difficult. It is a bad idea to use
proportions,
curing
times
are
plastic filler to a depth of much more
leisurely enough to avoid a problem
than 1/8 to 1/4 inch, and generally
with their setting up too fast.
less is better. Do not allow the easy
Apply the fully mixed filler to
layering capability of plastic filler to
the target area, and work it into its
encourage you to build up excessive
metal, again with your choice of
thicknesses with it.
tool. A flexible putty-knife blade or
Polyester components should be
plastic spreader works well for this.
rigorously mixed individually, to
After the filler has been applied, it
uniform consistencies, by kneading
should be spread with a plastic
As with lead filler, the mainstay
or stirring. Then, they should be
spreader and smoothed out into
8
of sanding this plastic filler was
mixed with each other on a hard and
approximately
the
contours
to
a board sander fitted with 80-grit
non-absorbent surface like sheet-
which it will be filed. As filler is
paper. You can see how the board’s
metal or shiny plastic. They should
spread this way, it is important to
position has been shifted slightly with
not be mixed on surfaces like card-
not trap air bubbles in it, and to
each stroke, so that the same stroke
board or on any waxed surface, such
work out any air inclusions that may
is never sanded more than once in
