One trick we discovered helps the process.  The Chemcut regenerator uses
timers to alternate between oxydiser and acid wehenever the redox is below
the setpoint.  The timers open solenoids to allow the big venturi to suck in the
components.  We found that by adding a third solenoid which is normally open
we could allow air to be sucked in whenever the two chemicals were not feeding.

The air helps complete the second etch reaction which is the conversion of
cuprous back to cupric.  This helps maintain consistent etch rate during heavy
loading.  My experience was with peroxide but I don't see why it shouldn't work
equally well with either oxidiser.

Relevant to safety, other than the drum incident which I described before, safety
was not a problem in the three years we used the system.

Eventually we switched to alkaline etch for more speed along with most of the industry.
I understand they are going back to cupric, since fine line considerations now
outweigh speed requirements.

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