- Some steps in metal refinishing
are rather prosaic. Stripping and sanding require some care
but not significant technique. Spraying requires a technique
that can be learned, partly by explanation and partly by experience.
Unless you have developed this technique, subjecting valuable
camera parts to sags, overspray and early peeling is a bad
- Serious metal refinishing--the
kind that good auto body shops do--involves expensive equipment,
considerable training, controlled conditions, detailed knowledge
and hazardous materials. With some care, you can do metal
refinishing that is attractive, reasonably durable, and safe,
using good quality spray cans in a clean and well ventilated
- In good metal refinishing,
you will spend 90% of task time in preparation. Accept it.
- 'Cleanliness' of prepared
surfaces is essential to a durable finish. Any
rust, oil or moisture on the surface of the workpiece will
result in early failure of your paintwork.
- All existing paint must
be soundly attached to the metal and all edges of existing
paint must be sanded smooth or 'feathered' or they will show
through your coatings as pock marks.
CLEANING THE METAL
- If possible, remove all
metal to be refinished from the camera body. It is possible
to mask areas, but it is difficult to prepare the surface
as thoroughly when the area to be painted adjoins surfaces
that could be damaged by solvents. Where masking is needed,
for example in parts of a body casting that aren't painted,
do your prep work first, then mask as the last step. Where
complete disassembly isn't practical, you can carefully mask
with masking of cello tape and protect larger areas with baggies,
craft bags or newspaper.
- Remove all optics from
metal parts and disassemble components.
- With small parts it may
be easiest to strip them of existing paint. You can use a
commercial paint stripper or soak them in a strong solvent
like lacquer thinner.
- After you have softened
the original finish remove all loose paint--an old toothbrush
is good for small parts. Rinse the parts well in paint thinner
(note that this is chemically very different from the lacquer
thinner mentioned above). This is an inexpensive rinse material
and it is compatible with the solvent base for most spraycan
paint. Two or three rinses will insure that you have gotten
all loose paint off. A safe and effective way to rinse small
parts is to get a good quality plastic food container with
a tight-fitting screwon lid. Put clean paint thinner and the
parts into the plastic container. Make sure that the lid
is tightly fastened and that no thinner is leaking out of
the sealed container, then shake vigorously. Do
not use lacquer thinner for this operation; it will dissolve
plastics and is too volatile and dangerous to be used safely
for this kind of operation.
- Finally dry the parts
and inspect for any rust. If you find some, use a small wire
brush to get down to bare, clean metal.
- If you have parts that
have rusted, causing pitting in the metal, you can use zinc
primer and sanding between coats to fill the pits and prepare
a smoother surface. Sand with 200-400 grit wet-or-dry sandpaper,
supported on a flat holder, especially for larger flat surfaces.
- Understand that getting
a good sprayed finish requires considerable practice--you
can't learn how to do this by only reading these instructions.
If you have no or limited experience, practice on some expendable
objects of about the same size and shape as the camera parts
you expect to paint. Be confident in your abilities before
attempting to paint valuable camera parts. Even if you do
have experience, painting one test object with the current
can of paint in the current atmospheric conditions will help
you judge your painting activity when you paint the camera
- Understanding how professionals
paint will help you set up operations that reduce your chance
of failure. The best paint locations have good ventilation
with minimum dust--a conflicting set of conditions. Paint
shops have paint booths with moderate air movement passed
through effective air filtration systems that supply clean
incoming air and eliminate the discharge of solids and toxic
vehicle fumes. Professionals use toxic paint materials and
wear special respirators that protect their breathing. You
can begin to approximate these conditions by finding
a relatively clean area--perhaps a garage with a clean floor.
Spraying it with a fine mist of water will settle dust on
the floor. Prepare a spraying area on a work surface well
off the floor by spreading clean newspapers over an area that
extends two feet beyond the surface of your workpiece. Support
your workpiece vertically by some clean object that won't
be damaged by overspray. Don't spray on a windy day; a dry
sunny day is best. Remove any nearby items that could be damaged
- Name brands of spray
are probably better. The paint may be of higher quality and
the nozzle may produce better results.
- The spray nozzle must
be clean. If this is a new can of paint that will probably
be true, but you should always spray a small test patch on
a test surface. Holding the can upside down and spraying for
a few seconds will clear the nozzle when you are finished.
If paint accumulates on the nozzle, wipe it away with a rag
moistened with a little thinner.
- Elevate pieces so that
bottom edges don't stick to the newspaper covering your work
surface. Use an item smaller than the workpiece to elevate
SPRAYING -- THE REAL THING
- Spray with the can in
a nearly vertical position.
- Move the can horizontally,
keeping it equidistant at about 12 inches from the workpiece.
- Start your spraying pass
to one side of the workpiece and finish it beyond the other
side of the workpiece--the paint spray pattern should be fully
formed when you reach the leading edge of the piece.
- Move smoothly and evenly--never
change your rate of movement or stop while the spray pattern
is still aimed at the workpiece.
- Start at the top of each
workpiece and work downward with successive passes.
- Spray three dimensional
pieces from each direction. If the bottom of a piece, as well
as its top and sides needs to be painted wait until those
sides have dried completely before resting the piece on a
newly painted surface to paint the bottom.
- It is easier to avoid
runs on horizontal surfaces, but more difficult to get even
coating if the area is very large. Horizontal surfaces also
are more likely to accumulate dust as they dry.
- You will see that one
pass produces a sprayed surface that is wet in the center
and powdery at the periphery. You want to create a sprayed
surface that has a uniform coating that is 'wet' across its
complete surface. This is done by having the top edge of the
workpiece in the 'wet' center area of your first pass. As
you make successive overlapping passes, the powdery area at
the top of each pass will be absorbed into the wet center
of the preceding pass.
- Probably the most difficult
area of judgment in spray painting is arriving at a balance
of paint quantity in each coat. If you get the surface too
wet, the paint will run; if your coating is to light, you
will have a surface with a powdery character caused by overspray.
This balance is affected by the paint material, atmospheric
conditions and how the nozzle atomizes the paint material.
There is no good way to describe this verbally--it is something
you learn by trial and error.
- Don't try to coat too
heavily. Several lighter coats are better than fewer heavy
coats. Only the final coat will affect the smoothness of the
surface, so erring on the side of overspray in initial coats
is preferable to sags caused by too much paint.
DRYING AND CURING
- Follow instructions on
the can for recoating. Drying time will be heavily dependent
on air temperature and humidity
- Baking the paint will
make it more durable. Baking at 200-250 degrees for several
hours will harden the paint. Obviously this can only be done
with metal parts that have no glass, leather or plastic components.
Baking paint produces unpleasant and sometimes noxious fumes.
If you have a small toaster oven that will operate reliably
in this temperature range, taking it outside or into a garage
will keep your house free from fumes.
- Allowing the paint to
cure for several days before attempting reassembly will keep
it from getting marred by handling.