I think the answer was a tiny wire

My first response, take a piece of cloth, not paper towel, not silk, but even a shop towel, better cheesecloth or something similarly soft and run it around the rim and tire, actually, "bike shop lesson 101, long before patching, find the cause", not to be rude, just common sense, err, not having the proper tool is disastrous, err, the proper tool would have been a cotton towel to find the culprit.