FWIW My method for treating family member for shingles several years ago...I dug out my old battery unit, and using rain water for speed of production, made a batch in the morning and consumed, then made another in the afternoon and consumed that. Did this for 4-5 days from memory, don't think I documented silver intake after that period.
I didn't spray any on either, just administered it internally, worked fine as far as I was concerned. I think one may need to start as soon as one can if shingles is believed to be starting, and hit it hard and fast, I didn't have the opportunity of administering it to this person until pain and rash was becoming evident, but for all intent and purposes he was well on his way to full recovery in a week, with only a handful of blisters which actually broke after that, the rest healed internally. No question about believing it worked in my mind. Make it and take it *immediately* after cessation of brewing to maximise ion intake.