This works because the solvent base for the ink is alcohol, so a much simpler method that doesn't waste ink is to use a small spray bottle of isopropyl alcohol. Ideally 99/100%, if you can get it. (Try eBay.)
This doubles up as an effective whiteboard cleaner.
Isopropanol is relatively safe to drink in small amounts (single digit mL). It's only about 2x stronger than ethanol, and your liver metabolizes it to acetone, which is safe.
Denatured alcohol contains methanol, which is way more dangerous since you metabolise it to formaldehyde.
Source: I unknowingly got drunk on IPA fumes before work one time and wrote some really bad code
Methanol is indeed quite toxic but it is not the only denaturant. There are many others [0]. When methanol is used as a denaturant, special labeling is required [1]. Most of the denatured ethyl alcohol I've seen in pharmacies in recent years has not contained methanol but merely bittering agents, because methanol is so dangerous.
I second that. I discovered that IPA dissolves sharpie resin when doing DIY circuitboards via toner transfer. When you do toner transfer, you can use a Sharpie to fix up imperfections in the artwork before doing the etching. After the copper is etched, you remove the ink.
The first time I did that, I tried IPA first, and that took off the Sharpie touch ups, not doing anything to the laser printer toner.
Next up, acetone: swoosh, clean copper in one wipe.
You can do the same with a Sharpie. All inks contain a solvent for their pigment, so you can use the same marker to remove the same ink. Just mark over it and immediately wipe it off.
