Chris:

At risk of repeating myself, ionic contamination is almost always a result of
a SLOWLY dissolving metal deposit, likely in your case to be imbedded pumice.

You need a chemical clean that will dissolve that residue.  In your case, you
may be lucky, and it may be as simple as a simple acid wash.  If that is the
case, it could be rapid, and run unheated.

If however, the laminate/soldermask has reacted with the metallics, you will
need an alkaline, chelated, product, which will take longer, and require a
heated solution.

A number of vendors supply such chemistry, including us.

Contact me directly, if you would like more information, or samples of our
magic.

Rudy Sedlak
RD Chemical Company
[log in to unmask]
phone 650-962-8004

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