From the manufacturer's website:

The Quickshade Red Tone Wash is loaded with red and heavy black pigment in the popular Warpaints ink resin base. Use on top of white for an instant red toned and shaded miniature or on top of yellow, orange or red colours for extra depth and shading.As all the Quickshade Inks, it looks stunning on a metal primer, giving it an evil Khorne look.Shading and colour toning in one wash.