From: Bruce Gentry via GreenKeys [greenkeys@mailman.qth.net] -- Monday, January 16, 2023 12:57 PM

> Relay contacts designed for millivolt level signals often have gold plating. ...
> Contacts carrying signals and current at intermediate levels, up to about ten amps, can be cleaned with a burnishing tool, ...

Amen.  As a rule, burnishing is not about removing material, it is about pressing a malleable surface back into a smooth state.  You don't want to abrade off the high spots, you want to smush (technical term) them back down.  Remember, silver, gold, nickel and copper are all very malleable.  Rough surfaces of those metals can be made smooth without removing any metal.

Of course, if there is corrosion, you want to remove that first.  Pinching the contacts together over a piece of plain paper and pulling it out is a pretty good way to do that.  Cellulose fibers won't be very effective at removing metal, but they will abrade the oxides.

Pinch a piece of polished shim stock like a feeler gauge between the contacts and you'll flatten the high points on both sides.  There's hardly any reason to move the shim stock while you're pinching.

The old advice for cleaning tape heads applies:  Non illitigemous carburundunum, translated as, "don't use sandpaper, you b-----ds!"

      Doug Jones
      jones@cs.uiowa.edu