noun
water-based ink
Ink that uses water as the main solvent, commonly used in fountain pens, calligraphy, and some printers.
この万年筆には水性インクを使ってください。
Please use water-based ink for this fountain pen.
Oil-based ink, which is water-resistant and dries more slowly, often used for permanent markers and industrial printing.
Compound of 水性 (water-based) and インク (ink, from English).