Never tried removing ink with it, but I've used rubbing alcohol to remove oily grime from old holsters - including some that are fairly desirable collector types such as Heiser, etc. Alcohol may not remove the ink, but it would be the first thing I'd try. No need to saturate the leather. Just wet a paper towel and rub it on the spot and I'd try to avoid spreading it out too far from where the ink actually is. Alcohol won't damage the leather. I use a saddle soap afterward to remoisturize the leather.

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