The KWZ standard inks are based only on dyes that are easily soluble in water. The result is that the ink does not have virtually no water resistance. The KWZ ink comes in 60ml glass ink bottles and is available in 40 colors.
KWZ (pronounced Ka Veh Zeh) Ink is a small company that produces handmade fountain pen inks and is based in Poland. It all started for Konrad Żurawski as a hobby in 2012 with producing iron-gall inks and now there are over 100 different inks available!