Greg:

You have discovered one of the great secrets of the industry....

The ammoniacal etch replenishers arrive with widely varying contents.

I consulted for a distributor of this chemistry, and had the same sort of
problems, and started analyzing the incoming stuff, and was stunned.  The
vendors can get away with it because virtually nobody analyzes their incoming
replenisher.

The vendors specs are usually wider than they ought to be, and they
frequently do not even meet their own specs.  (As a chemical vendor, I can
tell you that the most casual QC can keep any ingredient within 1% of
target....wider than that is self-serving)

Now, this caveat, the experience I write about above is 10+ years old, so, it
MAY no longer be applicable...however, if I were to bet, I would bet it has
not changed.

And incidentally, the chloride level does not change in the etching process,
so, there is no "controlling" it, assuming that you are not adding anything
to the replenisher.

Good luck.

Rudy Sedlak
RD Chemical Company

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