Bartosz, any ink will act as an etch-resist.

Nevertheless, there are great differencies of suitability! A 'Dalo 2M Professional' has a much better ink than an 'Edding 3000'. Dalo's ink is thicker and adheres much better than cheap inks.

Also, even if ink is adhereing perfectly at room temperatures, it's quite a difference, when PCB is put into warm acid. The most inks I know loose contact if acid is warmed up a bit, or if acid is relevantly concentrated. But working with low concentrated and cold acids isn't a remedy either, because then etching time increases annoyingly...

Kai