This is just a quick test. The ink was Noodler's Bulletproof 'Bad Belted Kingfisher'. The words were written on a piece of printer paper then let dried for about 5 minutes. I then ran hot water from a faucet continuously about 2 inches above the writing for about 1 minute. The color seemed to lighten but the bottom picture was taken immediately after the hot water test and the paper was still wet. Amazing!!


The top picture was taken before the hot water test. The bottom picture was taken after the hot water test.


This ink can even resist bleach, paint thinner, alcohol and other chemical. Now finally I can sign my checks and address my envelopes using fountain pens!