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OK, so that's not what Marlin Brando
had in mind when he uttered those words in the movie Apocalypse
Now. I think it's safe to say, however, that the idea of doing a
natural metal finish conjures up all kinds of dark fears in many
modelers.
So what's so hard about doing a
natural metal finish (NMF)? Well, there are at least two issues
that must be dealt with to achieve a good NMF. One is that the
surface of the model must be extremely smooth, almost
mirror-like. Unlike typical camouflage or drab military color
schemes, any blemish or minor fault will show through, and
actually seems magnified by the NMF. Secondly, there is the
issue of "tricking" the eye into thinking that it's
looking at real aluminum when it's actually looking at paint.
This can be facilitated by using various shades of
"aluminum", polishing out some panels more than
others, etc.
There are many ways to approach
the problem. My first natural metal finish was done about 10
years ago using the Floquil Railroad color "Old
Silver" and polishing it out with toothpaste after it had
thoroughly cured. Not exactly virtual aluminum, but it looked
pretty good. I've also used SNJ, Alclad and Alcad II paints with
success. These paints can be supplemented with SNJ aluminum
powder which when buffed into the painted surface, will yield a
brilliant and metal like finish. The Model Master buffable
paints are useful for masking and highlighting specific panels,
but too delicate for the overall finish (in my humble opinion,
of course).
For my latest project, the Tamiya
F-84G, I thought I would try something a little different,
combining some tricks I have learned in the past with a couple
of new ideas.
Preparing the surface.
Fortunately, I started with an extremely well engineered model,
the 1/48 Tamiya Thunderjet. The parts fit together beautifully.
This meant that I did not have to do any major surgery or
extensive puttying and sanding. The seams were joined with MEK
(methyl ethyl ketone) applied through a Creations Unlimited
liquid glue applicator. This little jewel is great for ensuring
that you get the glue medium exactly where you want it. After
the seams were dry, I used a White Out pen and ran it along the
seams. The White Out pen is an improvement of the "old
brush in a bottle" applicator that has been around for
ages. Similar to a roller ballpoint pen, the White Out pen
deposits a narrow line of White Out which can be precisely
applied. Once the White Out is dry (I usually give it 5
minutes), the excess can be sanded gently away. I recommend
starting with 600 or 1000 grit. I have even used 3200 grit
effectively as a starter. In most cases, you will not need to
use a grit coarser than 600. Remember, the courser the grit you
start out with, the more scratches you'll have so sand and
polish out.
This procedure will take care of
most seams- remember, even the smallest imperfections will be
glaringly obvious with a NMF. For those micro pits which
persist, I apply a thin layer of super thin cyanoacrylate with a
Microbrush. Put a small amount of super thin superglue in a
bottle cap, dip the Microbrush in the glue, and run it quickly
across the seam. After drying for a few minutes, the seam can be
sanded and polished. This should take care of any pesky
imperfections in the seam.
Polishing the Plastic. To polish
out the plastic I use Micromesh polishing cloths. These come in
a set and range from 3200 to 12000 grit ("grit" hardly
seems the appropriate word to describe the higher number cloths,
which have no perceptible grain). I try to start with the
highest number possible in order to minimize the amount of
polishing needed and avoid any sanding scratches. Do your work
under a bright lamp. The kind that combines a lamp and
magnifying glass is best as you can inspect your work as you go
and detect any imperfections in the plastic. Large areas of the
model surface may be shiny and smooth enough right out of the
box to bypass this step. You don't need to achieve a mirror
finish at this stage. The next step will take care of that.
Once you have sanded and rinsed
the sanding dust off the model and let it dry, a coat of Future
Floor wax can be applied. It can be airbrushed, but I've found
that the finish seems smoother and glossier if I use a wide flat
brush (½" or 1") for application. Dip the brush into
a small container of Future, rake off the excess, and apply a
thin coat using one continuous stroke. For example, if I am
applying Future to a wing, I might start at the wing root and
drag the brush all the way to the wing tip without raising it
off the model's surface. Immediately go back and load the brush
with Future, rake off the excess, and apply another thin line
parallel and slightly overlapping the first. If you need to go
over an area again, do so immediately. Future sets up quickly
and waiting more than 20 seconds to rebrush an area will result
in visible brush marks. On the positive side, because Future
sets up so fast, you can reapply a second coat to the model
within 5 minutes. Usually two or three coats are all that will
be needed to produce a mirror finish. Now set, the model aside
for 24 to 48 hours.
Final polish. Once the Future has
cured, inspect all surfaces under a bright light. Look for small
imperfections. There will probably be some minute grains of dust
imbedded in the Future. You can the polish these out. Start with
6000 grit polishing cloth, then 8000, then 12000. Wet each
polishing cloth with a little water, and gently polish the
surface with a circular motion. This will usually smooth out any
small imperfection. If you need to, you can reapply Future over
the area to restore the shine and ensure a smooth surface.
Time to Paint. Now for the moment
you've been waiting for- applying the paint. Although I've used
SNJ and Alclad, I decided to try something a little off the
beaten path for this model- Krylon spray chrome paint. In order
to airbrush the paint, it was obvious I was going to have to
remove it from the can. First, I held the can upside down and
kept the nozzle button depressed for several minutes until all
the propellant was expended. Once this was done, a small nail
was used to punch a hole in the can beneath the nozzle. (If you
do this, BE CAREFUL, there may still be a small amount of
pressure inside the can). Leave the nail imbedded in the can
until the propellant is completely gone. This will allow the
propellant to escape while minimizing any paint loss. Then you
may remove the nail and pour the paint out into a container for
storage. I know this procedure sounds a little scary, but it can
be done safely if you take your time and use common sense.
The Krylon was very thin coming
straight out of the can, but I found that I got better results
if I thinned it even more before airbrushing. I tried lacquer
thinner, which worked well. I then tried using a medium
temperature automotive paint reducer (available at most auto
parts stores), and than worked even better. I thinned the Krylon
50/50 with the reducer, then airbrushed at a very low pressure
(between 10 and 15 psi) within 6" of the model's surface. I
started with a mist coat, working with one section at a time (a
wing, for example). After misting on a coat, you can go back
over the same area with a slightly heavier coat. In fact, I
found that a heavier coat was needed to produce the brilliant
shine which looked almost like real chrome. One point of
caution: only use this type of thinner if you have very good air
circulation (e.g, a vented paint booth with an exhaust fan) AND
wear a dual cartridge respirator (can be purchased at Lowes).
Shading the finish. Shading
individual panels will break the "monochrome"
appearance of the finish and give your model a more 3
dimensional look. Shading can be done in several ways. Rather
than darkening the original chrome paint or apply another paint
such as Testors Metalizer, I tried something different. First,
select the panels you want to contrast with the overall finish.
This is where reference material comes in handy. Individual
panels must be masked off. This can be done with low tack
drafting tape. For this job, however, I used Parafilm. The
Parafilm was stretched, allowed to relax, and then applied over
and well beyond the boundaries of the panel which is to be
painted. Next, I CAREFULLY cut along panel lines with a NEW #11
blade and removed the Parafilm from the panels which were going
to be painted. This left a very precise and cleanly masked
border around the panel. I then thinned a Tamiya clear color (4
parts alcohol/1 part paint) and airbrushed it onto the panel,
gradually building up the color with light mist coats. I used
the Tamiya clear yellow to shade some areas, and the Smoke color
for others. You can also mix the clear Blue and Smoke together
for another tonal variation. Starting with heavily thinned paint
allows you to build up the shading gradually. Because the colors
are translucent, the underlying aluminum paint will appear
darkened, not repainted.
Once the shading was complete,
the Parafilm was removed, and a final thin coat of Future was
handbrushed onto the model. I know that some modelers would
consider applying a topcoat over the NMF as sacrilege, but I was
pleased with the result. The Future is thin enough that it
simply gives shine to the paint without really looking like a
topcoat.
Once the Future had dried, I used
artist's black watercolor heavily thinned with water and a drop
of dish washing detergent to create a wash for panel lines. This
was allowed to dry and the excess was then wiped off with a
paper towel very slightly dampened with water. Decals were
applied next.
So, that's it. My
"method" of producing a NMF was really an experiment
that fortunately worked out well. I'm certainly not advocating
this as being THE way. I think it does illustrate though, that
you don't have to do things strictly "by the book" to
get good results.
Materials List:
· Future acrylic floor wax
· ½" to 1" flat brush
· Micromesh (or other brand)
polishing cloths
· Krylon Chrome spray (or some
better know modeling metalizer paints such as SNJ or Alclad II)
· Medium Temperature Automotive
Enamel Reducer (or lacquer thinner)
· Dual cartridge respirator
· Tamiya clear Smoke, Blue,
Yellow
· Isopropyl alcohol, or Tamiya
thinner
· An Airbrush (of course)
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