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-   -   Claude Lyons 8A variac - electrolytic rust removal (https://www.vintage-radio.net/forum/showthread.php?t=140544)

mark_in_manc 15th Oct 2017 6:21 pm

Claude Lyons 8A variac - electrolytic rust removal
 
Hi folks

I just bought some workshop equipment from the estate of a guy who made clocks among other things, and who had once had an industrial unit. When the unit was sold, he brought it all home - lathe and miller in the kitchen, two more lathes and a pedestal drill in a bedroom upstairs ;D. He must have got some of it up the stairs using the stair lift (really - he was disabled and a good age). Best use for a stair lift I think I have come across!

Anyway, I felt sorry for a Claude Lyons 8A variac which I found in a drawer. It was seized - the plastic (bakelite?) spindles swell when stored damp, and seize in the aluminium top /base plates in which they run. Being damp, the Al was furry and the steel mesh outer casing was bright red rusty.

Being very light gauge steel and having a complicated square mesh pattern cut into it, the casing was going to be awkward to clean up using abrasive methods without damaging it. So I dug out some caustic soda, made it up in a plastic bucket, found some plasterers mesh to use as an anode, and made the casing pieces the cathode. I put a couple of amps through it for 24 hours or so, for each piece.

After that, all you do is run it under the tap and rub lightly with one of those metal-mesh pan scourers. Red rust converts to black iron oxide powder (I forget which formulae - someone will know) which scrubs off easily and leaves darker-coloured but clean metal underneath. If you use caustic as your electrolyte, it also takes existing paint off very nicely.

I liked the patinated look so I varnished it. Others might have given it a more original coat of gold or light-brown Hammerite.

I'll add a photo once I find my camera - so this is a just a 'heads-up' for the electrolysis technique, which can be very useful for light-gauge steel work.

(Mods - on reflection this might be better in 'hints and tips' or 'chassis and cabinet restoration' - please move as you see fit).


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