[R-390] My 2 cents regarding cleaning RF decks

[Tisha Hayes]

 I am not surprised by the discoloration of the brass gears or the aluminum
plate during a soaking in any solution that does not have a neutral pH.

Brass and Bronze are more cathodic than aluminum (.4 V compared to .9 V).
Since the parts were soaked together you will get a current flow (~.5 V)
between the dissimilar metals and it will show up as discoloring at first
and eventually at wholesale corrosion (pitting, ultimate dissolution) if
left that way for any time.

With any sorts of acid of alkali cleaning solutions you should only wash
components of a similar chemical make-up together. Even the bronze bushings
in an aluminum panel will begin to react and eat away at the aluminum as
aluminum is "sacrificial" to a more noble metal (gold, silver, nickel,
copper, bronze and brass).

Alkali earth metals (anodic) like magnesium, zinc, aluminum, etc... will go
into solution and plate out on a noble metal. This can be an acidic, alkali
or salt solution. As you mentioned we do not know if any of the cleaning
solutions are at a perfect pH of 7.0 or if they stay there as contaminants
build up in the bath.

-- 
Ms. Tisha Hayes/ AA4HA
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"I'll be a diode, cathode, electrode
Overload, generator, oscillator
Make a circuit with me." -- The Polecats