white powder on Drake AC-4 chassis
 

Hi, all concerned:

I suppose this stuff is oxidation from loooooonnng storage.

How do I remove it without taking the lettering off, pls? Vacuum?

The ps is in a gpc RV3 case and powers it and a gpc TR3.

I intend on getting them into goc as well, and then trading up to a
TR4CW/RV4 for a modest glowbug station.

TIA & 73,
Dave, N3HE
Cincinnati OH

David J Windisch wrote:
Hi, all concerned:

I suppose this stuff is oxidation from loooooonnng storage.

How do I remove it without taking the lettering off, pls? Vacuum?

The ps is in a gpc RV3 case and powers it and a gpc TR3.

I intend on getting them into goc as well, and then trading up to a
TR4CW/RV4 for a modest glowbug station.

TIA & 73,
Dave, N3HE
Cincinnati OH

Old steel chassis boxes are frequently zinc or cadmium plated. When the
plating gets damp, it oxidizes. If it is zinc plated, you get a white
powder that is zinc oxide. If it is cadmium plated you get a yellow powder
which is cadmium oxide.

If you scrub, you will make a chassis that looks scrubbed. What I sometimes
do is blast the majority of the dust off with compressed air, and a gentle
dusting with a paint brush..

-Chuck

On Fri, 28 Jan 2005 21:05:17 -0500, Chuck Harris
wrote:

David J Windisch wrote:
Hi, all concerned:

I suppose this stuff is oxidation from loooooonnng storage.

How do I remove it without taking the lettering off, pls? Vacuum?
snip---
Old steel chassis boxes are frequently zinc or cadmium plated. When the
plating gets damp, it oxidizes. If it is zinc plated, you get a white
powder that is zinc oxide. If it is cadmium plated you get a yellow powder
which is cadmium oxide.

If you scrub, you will make a chassis that looks scrubbed. What I sometimes
do is blast the majority of the dust off with compressed air, and a gentle
dusting with a paint brush..

-Chuck
Chuck,
Any idea what plating Heathkit used on the HW-single-banders? I have
one that has gone directly to the Iron oxide stage.

TW writes:

If you scrub, you will make a chassis that looks scrubbed. What I sometimes
do is blast the majority of the dust off with compressed air, and a gentle
dusting with a paint brush..

-Chuck

DO NOT blow off the dust. If it is Cadmium, you are poisoning yourself
and your work area. Rinse it off, but don't scrub. Then use a thin clear
acrylic to seal it. Very nasty stuff. Cadmium is a much more lethal
item than asbestos.
--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA

Steven Swift wrote:
TW writes:


If you scrub, you will make a chassis that looks scrubbed. What I sometimes
do is blast the majority of the dust off with compressed air, and a gentle
dusting with a paint brush..

-Chuck


DO NOT blow off the dust. If it is Cadmium, you are poisoning yourself
and your work area. Rinse it off, but don't scrub. Then use a thin clear
acrylic to seal it. Very nasty stuff. Cadmium is a much more lethal
item than asbestos.http://physchem.ox.ac.uk/MSDS/CA/cadmium_oxide

Interesting, but wrong!

Cadmium oxide is indeed deadly stuff, but it is a dark brown powder,
not white. Read the MSDS that you quoted. It is on the first line
under "Physical Properties".

The white powder on the chassis is zinc oxide, the stuff that is in non
PABA sunblock lotions.

It almost takes an act of congress to turn cadmium plating into
cadmium oxide. Very high temperatures, and air will do it; water won't.

As a welder, I potentially come into contact with cadmium oxide anytime
I try and weld a piece of galvanized steel. When steel is prepared for
galvanizing (zinc dipping), it is first pickled (acid etched), and then
given a microscopically thin electroplating of cadmium to prevent flash
rusting. Then it is dipped in zinc, or zinc electroplated. When you heat
the metal to welding temperatures, both the zinc, and the cadmium turn
into their respective oxides. The result appears as a very light yellow
powder. Light yellow, because it is mostly bright white zinc oxide, with
a very tiny touch of brownish cadmium oxide. As fledgling welders we were
taught that zinc oxide would give you a 24 hour fever, but was harmless,
but cadmium oxide would make you dead, so avoid welding cadmium plated
steel.

-Chuck

Chuck Harris wrote:

Cadmium oxide is indeed deadly stuff, but it is a dark brown powder,
not white.

Chuck- What about that yellow-green looking stuff we sometimes
see on chassis that we know were Cadmium plated?
That the bad stuff?
If so, I should probably be dead- I washed some of that powder
stuff off with my bare hands many years ago.
D.S.

David Stinson wrote:


Chuck Harris wrote:

Cadmium oxide is indeed deadly stuff, but it is a dark brown powder,
not white.


Chuck- What about that yellow-green looking stuff we sometimes
see on chassis that we know were Cadmium plated?
That the bad stuff?
If so, I should probably be dead- I washed some of that powder
stuff off with my bare hands many years ago.
D.S.

Hi David,

Cadmium oxide is not water soluble. It is mostly an ingestion and
inhalation hazard as I understand it.

I have seen that kind of corrosion on some items, I was never sure
just what it was. Typically it appeared on small screws and standoffs
that otherwise had a rather flat whitish/gray appearance, not shiny at
all. There are so many different treatments that were used on metals,
it would be hard to keep track of them all.

I have had numerous bits of hardware that I bought new that were sold
as being cadmium plated. It was a standard item from the 60s thru
the 80s. They are shiny, and bluish grey in color. I have never
seen them display any sign of corrosion, despite storing them for
years in a damp basement.

-Chuck