This is a high tint strength colour, a very clean mid red with a slightly bluish undertone. It is semitransparent and makes good glazes and is useful for mixing transparent browns. Naphthols are synthetic organic pigments developed in the mid-1960s. They are very useful for achieving the full range of nuance in red since we can see so much subtlety in this colour area and there are not many pigments which are good enough for artists use in this colour area. Naphthols can be used as an alternative to cadmium reds and are both less expensive and free of considerations of toxicity. However, as they are cleaner, they are less “natural” looking than cadmiums, especially when used in pale tints, and they are not quite so opaque.
This pigment is often the red used in industrial automotive finishes such as fire trucks. While naphthol medium red may look like a “primary” red, it is not magenta enough in colour to make a clean looking purple when mixed with blue. It is an economical pigment with a very good lightfastness performance even in pale tints with titanium white.