While it may look like a brown, this is a tremendous saturated yellow with depth which expands the gamut. It is incredibly useful- maybe almost indispensable for increasing the range of hues in oil paint and also for depicting lower-lightness high-chroma yellows.

As many painters will tell you, it can be difficult to descent down into the lower lightness steps of yellows. One may start out thinking it's as easy dancing the Grapevine step only to find out it's more like a Viennese Waltz. PY150 is a color that can help maintain high chroma in difficult mixes.

All the while Nickel Azo Yellow maintains solid 8's (highest marks) for lightfastness on the blue wool scale. There may be a slight difference in lightfastness when mixed with Lead White.

This color goes through some fun spinning turns of its own as a person increases the value by adding Titanium White. In masstone it looks like a dark brown, but it has hidden high chroma glazes and tints. Toxicity is a B, so handle with care. Monona Rossol's work has a section on health problems from nickel pigments in the Artist's Guide to Health and Safety. Her most recent research can be found through her site.