There are a lot of antiquities sellers who are vested in keeping overall populations low. They will sell anyone an antiquity, but then give the buyer instructions on how to DESTROY the piece, versus conserve it. A buyer must be aware of this. Oil treatments, brushing, and the like are detrimental to ancient bronze and silver, and many of the antiquities dealers know this, even though they peddle that kind of information in their sales.
My booklet Sustainment Metallica is now a part of my book "BOOK: TREASURE HUNTING WITH METAL DETECTORS AND OTHER TOOLS OF HIGH VALUE SALVAGE BY BILL GALLAGHER." I sell the book on ebay (And Here, write email@example.com) to metal detectorists and people who need the metal conservation method. I recently purchased a small lot of very encrusted coins, and after they were about 90-98% finished I took pictures of them, to make an advertisement for the method, so that my buyers can see what I accomplish. Below is the picture w/blurb for my new ads about my book.