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Restoration of Cheap Metals used as RF Shielding

E

EagleTG

Experienced Member
Joined
Sep 19, 2015
Messages
231
Location
Near Allentown, PA
I've run into various cheap/thin metal parts that are commonly used for RF Shielding (and a few other purposes) within our beloved vintage computers. Generally speaking, I see these more in the microcomputers than elsewhere. Commodore is awful with it, Apple uses a ton of it in everything they make (but the Apple stuff usually holds up a bit better in my experience), Tandy too.

This metal seems especially susceptible to rust/corrosion/losing it's shine. It also tends to corrode via finger prints of prior technicians, moisture/humidity and spilled beverages.

I've not had much luck in restoring this metal to any sort of acceptable level. The plastic polish Novus #2 actually works about the best of anything I've found, but tends to be tedious to use (especially in the corners of the metal) and is harsh on the cleaning rags around the corners/edges of the metal.

Has anyone found a decent way to clean this stuff up? Preferably, some sort of submersible way where I can "set it and forget it". I'm thinking of some form of rust/corrosion remover. Maybe Naval Jelly? Possibly one of the Tarn-X products? Maybe Nevr Dull (the weird wadding stuff)? What have you all had luck with?

Alternatively, I am considering prepping the metal parts in some way and then spray painting with a grey/silver primer and/or paint to freshen the look a bit. Still concerned about the rusty areas with this approach though.

I know it's inside the machine and all, but it really bugs me especially when you can see the rust/corrosion through the vents of the machine.
 
plain old vinegar seems to do well with rust and other forms of corrosion, course its cheap and plentiful

it wont restore the plating or the shiny of course that has been eaten away by whatever your removing
 
Hmm, I'm seeing that on YouTube videos regarding rust removal. I'll give it a go. I've got plenty of cheap white vinegar around for cleaning battery-related PCB corrosion, never thought to try it on metal plates.

I bet a polishing with Nevr Dull would bring back some of the shine after rust removal with vinegar. Hmmm... This calls for some weekend experimentation!
 
I had a buddy use vinegar to clean the rust off his honda handlebars, I use it to remove tarnish off copper quite a bit, and if you mix in a dash of table salt and a tiny amount of hydrogen peroxide and it makes a good PCB enchant lol, handy stuff to have around
 
A lot of steel parts are zinc-plated (galvanized) as protection against rust. Unfortunately, the zinc is a "sacrificial" metal that gives of itself to protect the underlying steel. It also is corroded by skin oils (fingerprints).

You can restore the coating with a plating kit Caswell offers various ones, for example and there are several DIY solutions. It's not hard. Surface prep is important, however and in this respect, cleanliness is next to godliness.

Another metal used for protection used in protection of steel parts is zinc chromate--it has a yellowish color, but involves chemicals now on the hazmat list. However, Caswell also has a kit for treating zinc-plated parts to restore the yellow color.

Nickel plating is more "warm" looking than zinc and electroless nickel is easy to plate.

On older equipment, you'll also find cadmium plated parts, particularly hardware. That's really off the table nowadays. You'll have to be happy with zinc.

Although I've restored zinc plating, the easiest thing is to polish the naked steel and coat with a clear polyurethane lacquer.
 
Quick additional comment, I've found some references to using crumpled aluminum foil along with vinegar to help when you need a bit more aggressive rust removal. Apparently you use the aluminum foil ball as a scrubbing element.

I haven't tried any of these methods yet, but I will report back once I do.
 
Naval jelly will convert rust back into steel. So will Coca-Cola. Or wood bleach. None of these will make it shine.
 
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