Cutting oil 1960s chassis practice

[centervolume]

Thanks everyone - Im pretty sure the answer is that the chassis was hot dipped in zinc as protective coating. In some moist environments like here in southeast, the oxidation accelerates and when untouched can build up and even start to yellow. Amps with greater use seem to have more opportunity for any oxidation to be diminished by abrasion etc.

Cadmium oxide would have been more reddish.

Here is a discussion I was able to located with further links embedded about the mysterious white powder found (even on non-coke addicts) amps

Mysterious oxidation

 

[Joe Gwinn]

Yes it is magnetic. Fender used sheet metal (steel)

From the age (and that it was Fender), I assumed it was steel. But maybe they changed to aluminum without telling me.

The slightly yellow dust reminded me of cadmium.

 

[GregSY]

If it was me, and I were worried about the appearance or longetivity of it, I'd blast those parts then have them dry film (Teflon) coated in silver. Never have to touch them again.

 

[centervolume]

From the age (and that it was Fender), I assumed it was steel. But maybe they changed to aluminum without telling me.

The slightly yellow dust reminded me of cadmium.

Well dang now you got me knockin on the door of worry again- I thought it would be more reddish if cadmium ?

 

[Joe Gwinn]

Well dang now you got me knockin on the door of worry again- I thought it would be more reddish if cadmium ?

Cadmium oxide is yellow to deep red, and dissolves in water, so it doesn't accumulate. When I was a kid, most hardware-store steel hardware was cadmium-plated for corrosion resistance, one never heard of someone being poisoned by it outside of industrial plating shops. (Now days, that hardware is zinc plated.)

Cadmium sulfide is yellow, but insoluable in water, so it could form (from sulfur in the atmosphere) and accumulate. It is widely used as a pigment.

 

[trevj]

Cadmium oxide is yellow to deep red, and dissolves in water, so it doesn't accumulate. When I was a kid, most hardware-store steel hardware was cadmium-plated for corrosion resistance, one never heard of someone being poisoned by it outside of industrial plating shops. (Now days, that hardware is zinc plated.)

Cadmium sulfide is yellow, but insoluable in water, so it could form (from sulfur in the atmosphere) and accumulate. It is widely used as a pigment.

Late eighties I was heavy into Brit bikes and the shop I part timed in regularly sent out nuts, bolts, and hardware to be CAD plated. It all came back silver colored and sorta crystalline looking on the surface, which was a pretty close match for the OEM stuff. Very white-silver.
The CAD plated hardware store nuts and bolts always had a yellow-gold-ish hue to them.

 

[technocrat]

Late eighties I was heavy into Brit bikes and the shop I part timed in regularly sent out nuts, bolts, and hardware to be CAD plated. It all came back silver colored and sorta crystalline looking on the surface, which was a pretty close match for the OEM stuff. Very white-silver.
The CAD plated hardware store nuts and bolts always had a yellow-gold-ish hue to them.

The gold hue is when they are passivated, same as for zinc. The older passivation technology used hexavalent chromium, which is rather nasty. The newer passivation dips are much more friendly.