As snazz says, Noodler's bulletproof is pretty good, smudging is still a possibility with it but depends more on the paper you use. Another good one is De Atram

As snazz says, Noodler's bulletproof is pretty good, smudging is still a possibility with it but depends more on the paper you use. Another good one is De Atramentis Document Ink (better than the Noodler imho)