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Andrew S.Richard, most of the attempts to pin down ink to an exact timeframe has been in the contesting of Last Wills and Testaments and very seldom has it been used for autograph authentication purposes. Here is just one example from a court case in Hong Kong where "dueling" experts opined regarding a wealthy Chinese man's will and they couldn't agree on what year the signature in question was penned:
http://www.rileywelch.com/HK%20Judgment_21NOV2002_bookmarks.pdf