[volt-nuts] OCD About My HP419A Attenuator Switch Gold Plated Contacts

[Neville Michie]

Potassium Hydroxide absorbs carbon dioxide from the air quite rapidly, so what you find on a circuit board is much more insoluble potassium carbonate and/or bicarbonate. Being an ionic compound you may well find copper carbonate, zinc carbonate, tin carbonate and lead carbonate from other metals on the board that have been dissolved. So judicious use of a weak acid, like acetic acid, may be necessary to dissolve these deposits. 
After that plenty of demineralised water and a long drying period in front of a fan.
cheers, 
Neville Michie