We do not recommend that you go pouring acid on your shoes, if you do, please take your feet out first. Sulfuric acid is a nasty acid with a pH of .3 when the Normality is 1, you definitely don't want to get this stuff on your skin. When poured into a shoe, it immediately dissolves the ink and starts eating away at all of the material. You can check out more of the reaction in the video above.