[evergreen]

I own an HP419A Null/Microvoltmeter. Those of you who are old enough, may remember using such an instrument in your Analytical Chemistry classes, or at work in the 1960s to 1980s. My instrument was tossed due to multiple failures. I have managed to bring it to working condition, but I'm concerned about the gold plated switch contacts used in its range selector. The instrument was permeated with potassium hydroxide salts from the dead nickel cadmium battery pack. I was able to clean off the KOH from affected printed circuit board material with boric acid. I would like to apply a polyphenol ether lubricant to the gold contacts to improve instrument performance. However, I'm concerned that there is a haze of KOH on the switch contacts. I was able to remove the epoxy glass circuit board from the instrument permitting me to completely flush the boric acid solution from the board with water. Applying boric acid to the switch contacts is problematic since the switch, is for all practical purposes, unremovable, and a thorough water rinse would flood the instrument.

I'm hoping, that since the KOH isn't bonded to the gold, that I can just spray the switch contacts with denatured alcohol which will quickly evaporate. Will the denatured alcohol be adequate to mechanically move off the KOH salt? Does gold have a property that would cause KOH to be repelled from it, and I have nothing to worry about? If the above proposed solution won't work, can someone lead me in the right direction?

Stan

[Borek]

I don't think ethanol will work. Sadly, the only thing I can think of is rinsing with plenty of DI water.

[Enthalpy]

Gold is easy to deposit, for instance electronics hobbyists can buy reactants to add a layer on the copper of printed circuits. So an alternative or complement to cleaning perfectly the existing gold would be to add a thin  layer of clean new one - provided this works on gold also.

To clean pure copper on printed circuits, I use the scratching back of a sponge. Less brutal than fine sand paper, but it does abrade copper a little bit and leaves it very clean. I didn't try on gold.

For gold-plated contacts on computer Ram modules, I use a rubber eraser. Easy with the flat shape there, efficient against hardened dust but sparing the metal. If your contaminant isn't too hard and the shape permits it, it's worth trying.