The Koh-I-Noor line of Universal inks was first developed for use with technical pens. The dye base eliminates the potential for cloggling the finest nibbed Rapidogaph Pens, and offers an intense color laydown. The shellac used in our ink formula creates a waterproof ink that can be used on both paper and film substrates. The black ink is highly opaque, and the white is semi-opaque, while the colored inks are semi-transparent. Not only are these inks ideal for use with Koh-I-Noor technical pens, but they can also be used with airbrushes, crowquill pens, and paint brushes. Cleans up easily with the Koh-I-Noor pen cleaner and Rapidoeeze pen cleaner system. The 1 oz. size has a convenient dropper spout ideal for filling technical pens and art markers. The larger size bottles of black ink have a flip up spout for controlled filling and mixing applications.