WTF ? White dust on Fender chassis's

[drewl]

Just WTF- is that white dust on Fender amp chassis's?

Some kind of corrosion, but man....this 70's Twin Reverb is the worst I've ever seen!

It's like a bag of blow exploded inside the amp.

Washed my hands like six times trying to get rid of that stank.

Funny, this amp looks brand frickin' new inside.

[The Dude]

I believe oxidation from zinc plating.

[J M Fahey]

Been talked about many times here.

When zinc plating chassis to protect from corrosion, zinc does not only protect iron passively, just separating it from air like paint, chrome, nickel, oil, grease does but also actively.

IF oxygen gets to iron surface (and it always eventually does) zinc still works by "suiciding" itself , letting some nasty zinc salt form, instead of deep burrowing iron rust.

So although your chassis (which must have been in a **very** humid spot or ages, salt spray or corrosive fumes present) looks ugly (and stinks), itīs structurally sound, all original iron is still there, no scales, pits, holes or cracked into big chunks, and be grateful for that.

If you were restoring it, you should empty the chassis and send it for refinishing (rteplating) ; if not, wipe it a few times with clean damp cloths until you remove most of it, then you may leave as is, wipe with some protective grease, or lightly spray with some rustproof paint (best) or at least some clear varnish.

Again, best is replating , zinc processors will remove old one chemically and apply new.

[Helmholtz]

Just WTF- is that white dust on Fender amp chassis's?

Some kind of corrosion, but man....this 70's Twin Reverb is the worst I've ever seen!

It's like a bag of blow exploded inside the amp.

Washed my hands like six times trying to get rid of that stank.

Funny, this amp looks brand frickin' new inside.

It is most probably zinc oxide (ZnO), i.e. corroded zinc plating caused by moisture. Earlier Fender chassis had a different metal plating, not prone to powder corrosion.

I would clean it with something like WD40.

[drewl]

Nice, Science!

This is the nastiest one I've ever seen.

[Jazz P Bass]

Wiki entry:
"Zinc coatings prevent oxidation of the protected metal by forming a barrier and by acting as a sacrificial anode if this barrier is damaged. Zinc oxide is a fine white dust that (in contrast to iron oxide) does not cause a breakdown of the substrate's surface integrity as it is formed. Indeed, the zinc oxide, if undisturbed, can act as a barrier to further oxidation, in a way similar to the protection afforded to aluminum and stainless steels by their oxide layers. The majority of hardware parts are zinc-plated, rather than cadmium-plated."

The part about 'if left undisturbed' struck me as interesting.

[J M Fahey]

Maybe.

After it has oxidized, it has no other function, and is fluffy porous, donīt see the advantage of leaving it behind.

That said, in part I believe that Wiki quote was written to avoid good-intentioned people to remove it in an aggressive way, such as sanding it, wire brushing it out, etc, until they are back to a shiny mirror surface ... which means iron is UN protected now and will dramatically rust in a short time.

Compared to that, "do not touch it" is a good idea.

But as I said, by itself it does not provide any extra protection (only the metallic zinc remaining is doing that job) smells bad, will stain hands and clothing, etc.
Not exactly a *poison* but I wouldnīt touch it and then handle cigarettes, sandwiches, etc. , so as said before, Iīd wipe it out with wet towels, blot dry surface and either leave as is (whatīs implicit in the wiki article), or if possible add some extra protection which will always help.
From wiping is with WD40 as Helmholtz suggests to light grease: you apply it with a cotton ball and then lightly wipe it away with a paper napkin ... *some* will remain of course, and thatīs enough, but it wonīt be so messy or lint magnet.

FWIW ships carry a sacrificial zinc plate or ingot in contact both with seawater and ship hull; after some time it will corrode and iron hull will be relatively intact.

[Enzo]

And do not touch your eyes either. Don't ask me how I know.

[Helmholtz]

The WD40 treatment I suggest will only remove loose oxide particles and its residue will have some preservation effect as it creeps into the porous surface. I might even consider applying a little gun oil (Ballistol) for long time preservation.
The main point is preventing moisture and salts from reaching the steel core.