30ml Holbein Acrylic Ink (HAI) flows like water and maintains the same pigment strength and intensity as found in Holbein 60ml Heavy Body Acrylic and Holbein 35ml Fluid Acrylic, but with a lower viscosity. It does not shift in color tone from wet to dried color and will not clog a .01mm aperture, flowing seamlessly through any airbrush, technical pen or refillable marker. Use directly for bold, brilliant color with a brush, airbrush, dip pen, technical pen or refillable marker. Dilute to achieve the subtle characteristics, washes and tones of watercolor painting. It is compatible with all Holbein water based media, and conforms to ASTM D-4236.