Morris,
I was curious why the stuff contained silver nitrate, looks like the sliver must form nano particles when used for disinfection purposes and the metallic silver likely reacts with the peroxide releasing its extra oxygen as part of its disinfection process.? There are numerous articles on Google.? Back to the question, the silver content is relative low so not likely to mess up the etching though I am not a chemist. ? ? Silver and for that matter most finely divided metals will cause the decomposition of hydrogen peroxide but so as long as the silver stays as a salt it's likely to be a non issue.?
I suspect that once you add the peroxide with silver nitrate? to your HCl the silver ions are going to react with the chloride and form an insoluble silver chloride precipitate that will settle out as sludge.
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