Semi-opaque black that works well with dip pens
"This is an excellent semi-opaque black. It is not as dark as some other black acrylic inks, but I think of it as a "shading" ink (thicker applications are slightly darker, and thinner applications are slightly lighter). It flows really well with dip pens, straight out of the bottle. Liquitex also makes assurances about pigment content and archival quality, which many other ink manufacturers do not make as transparently."
