over the years, is that it corrodes easily. It is quite common to find even brand new Cox sealed kits or spare parts, coated with a lot of white "crud"! Here a typical sample:
Cleaning
Magnesium Parts
By Ye
Olde Editor
One of the delightful legacies
from the Vintage Slot era of the 60's,
are the fabulous die cast
magnesium parts made famous by Cox.
Starting with the 1/24 Ferrari
and BRM F1 wheels, soon
to follow
were Ford GT and American
Mag (Cheetah) wheels in both scales.
The Lotus 30/40 wheels
were also offered in the larger scale. But to
my mind, the most beautiful
of them all were the 1/24 Chaparral wheels.
Until the introduction of
the "Iso Fulcrum" kits in 1967, the frames
of the Cox cars were also
die cast magnesium.
Magnesium was well known
for it's lightness, but was only used in
specialty applications,
such as full size race cars and the space
program, due to it's high
cost.
| The drawback
to magnesium, as many of us have discovered
over the years, is that it corrodes easily. It is quite common to find even brand new Cox sealed kits or spare parts, coated with a lot of white "crud"! Here a typical sample: |
|
Philippe deLespinay worked
at Cox in the 70's and tells us how
the parts were originally
made:
"The COX magnesium parts
were die-cast in steel molds and immediately dipped
in a protective bath
named "aludyne". They were then allowed to drip until dry.
This gave a matte, reddish,
uneven finish to the parts.
99% of the COX mag parts,
including sealed kits, have now suffered 35 years
of air or humidity corrosion,
with the result being a grayish, powdery finish
in the best case, and
a mildew-like white powder in the worst case, with severe
pitting if left in very
humid climate.
The very best method
to fix this problem is to finely glass-bead the parts in a
proper commercial sand
blasting machine (max 75 PSI pressure) and immediately
spray over,
a mix of 95% clear urethane and 5% candy-apple red color. When dry,
spray some
Testors "Dullcote" and you will have exactly the same finish as when
the parts
were new, PLUS the urethane protection which seals the parts from air
exposure,
guarantying a permanent condition.
Electric Dreams
can perform this service for anyone at a very reasonable rate.
The more parts
you send, the lesser the overall cost."
Ok, now I’d suspect that
most of us don’t have a Glass bead
blaster. While I could
probably buy a cheapie Harbor Freight
special, I’dprobably have
a hard time justifying it, and worse
yet, Lord only knows where
I’d keep it! So it’s time to investigate
other solutions.
This has been a popular
topic for years. The most common
suggestion is soaking in
lemon juice. A variety of other "home
remedies" have also been
suggested, but I’m not aware of
anyplace that has offered
a pictorial comparison.
http:// www.ProfessorMotor.com
has a nice pictorial on how-to
bead blast parts, but I
don’t know of any other site that has offers
pictures comparing other
methods. My apologies if there are others
who have already done this,
but I wanted to give it a try myself.
Ok, here we go…
The suggestions I’ve heard
about over the years are:
Henway, this time, I decided
to conduct a reasonably "controlled"
experiment, utilizing all
of the alternatives. First, I selected the
Cox Chaparral wheel as
the subject. There is the most detail in
these wheels. Plus, I had
enough of them in my junk box.
Here’s my test procedure:
One wheel was placed into
an old Mr Coffee scoop. The wheel
was covered with solution.
A 1/32 brass rod with the end bent
like a hook helped me fish
the part out.
Eventually, I figured out
that it was a lot easiler to put the wheel
on the hook before putting
in the solution! I’m a slow learner…
Each wheel was given 5 minutes
in the solution, then removed,
scrubbed with a toothbrush
(make sure it's your wife's, or as
Phil Thicthener suggests,
your 16 year old daughter's !!! ),
dish detergent and
fine brass brush, rinsed in water, then dried
with a hairdryer. The face
of the rims was then polished on a
sheet of 600 grit sandpaper.
By the by, all of the wheels started
out in approximately the
same condition, with the exception of
the bead blasted one, which
was a little worse than average.
On with the show...
First up was the popular
choice, good old lemon juice. My wife
donated half a lemon, and
squeezed it in this little gizmo she has,
which catches all the juice
and strains out the seeds – highly
recommended if you choose
to go this route. He’s the result:
As you can see, lemon juice
does a good job of removing
the crud. The spokes retain
the dark gray oxide, but overall,
it looks pretty good.
Next was the one I was sure
was going to be the best (besides
bead blasting), vinegar.
My wife didn’t have any white vinegar
on hand like I had tried
before, so she gave me some red wine
vinegar. The reaction seemed
to be similar to the lemon juice,
which was not what I remembered
from before. Here’s the wheel
after it’s vinegar bath:
The results are very similar
to lemon juice, with the
exception that you can
see that some of the dark gray
has started to come off
of the spokes.
Next, I tried cola – in
this case, "Is Pepsi OK? How about
Caffeine-Free?" The reaction
started out pretty good,
but pooped out in 2 or
3 minutes.
Here’s what it looks like:
Actually this looks OK also, and very similar to the others.
Next was a bathroom cleaning
product "Scrub-Free". I
presume that there is an
equivalent product outside of the
US, but I have no idea
what that might be…I had tried this
briefly a little while
back, by just spraying some of it onto
a grungy Cox mag frame,
and it didn’t really seem to do much.
This time, I filled up
the container by spraying directly into it
from the bottle. Here’s
what it did:
There appear to be a few
spokes that might need a little more
time, but overall, Scrub-Free
seems to work pretty well.
The next thing I tried was
the mechanical cleaning with a
brush in a Dremel tool.
The cup brush I had wouldn’t fit
down into the wheel, so
I switched to a stiff bristle brush
that came with my Dremel.
This approach does appear
to be able to clean off the wheel
pretty well, but I was
concerned about the possibility of too
much material removal,
so I stopped work,
and left this one
unfinished.
Finally, as a comparison,
I imposed on my buddy "Corvette Phil",
who has one of the Harbor
Freight Bead Blasters in his shop
along with the air compressor
to drive it…..
Well gang, "read ‘em and
weep" – this wheel is gorgeous!!!!!
All of the gray coating
is gone, there is a nice uniform finish,
and the detail really stands
out. OK, I’ll admit- glass bead
blasting is the BEST way
to go!
I put a protective coating
on all of the wheels to prevent
the corrosion from reoccurring.
What I used is a "Plaid"
brand Clear Acrylic Spray
found in the craft section of
Wal-Mart. This seems to
do the trick nicely.
I gathered all of the finished
wheels up to take them to show
"Corvette Phil". Since
I had left them on the kitchen counter.
My wife took a look at
them, plus the "before" wheel, and
immediately suggested another
product she has, called
"Lime-Away" (There are
a number of other Calcium, Lime,
Rust removal products that
are similar) I went back down,
found a really grungy Chap
wheel, and tried it out. The first
thing that one notices
is that the reaction is much more
vigorous than any of the
others. After 5 minutes, the part
was warm to the touch!
Here’s what it looks like:
Hey- the "Lime-Away" works
pretty good! IMHO, it does a
little better job than
any of the rest of the chemical treatments.
Notice that the spokes
are starting to come clean. What isn’t
as obvious here is that
this stuff took off most of the dark
gray oxide coating around
the outside of the wheel.
| It was getting late, so I didn’t take the time to spray the clear over the wheel. Next night, here’s what I found: |  |
Well, let’s sum it all up.
As I see it, any of the approaches
will work – it just depends
on what you’ve got on hand,
or how much you want to
spend. No doubt about it, bead
blasting is the best. The
Harbor Freight blaster is $80-$100,
plus another $35 or so
for glass beads, not to mention the
decent size air compressor
you need to run it.
If you’ve got a whole lot
of parts, this may be the best
solution for you. Or, you
can get it done for you by Electric
Dreams. Better yet, if
you can find a friend with a bead blast
unit who will do it for
you or let you try it…
Lacking this equipment,
if you have none of the other
chemicals on hand, buy
white vinegar – it’s the cheapest
at about $2 a gallon (as
I recall), and will last you a loooong
time. For a minimum investment,
buy a lemon, or a can of cola.
"Scrub Free" and "Lime-Away"
are bound to be a least a couple
of bucks for a quart, but
they probably do a bit better job.
OK Gang, there you have
it.
Now, there’s no excuse
for having grungy Cox wheels and frames!!!!
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