Also, while not a commercial set, this paint is mentioned as part of Williamsburg’s six Chromatic Darks. From their publication, Just Paint they explain, “These colors are all blends, containing a natural iron oxide or Ivory Black and one or more strongly colored pigments to give them their chromatic punch. When painted from the tube, they visually resemble a colorful black, but when scumbled, tinted or mixed, these darks start to show their true color!” In regards to Payne’s Grey specifically, “Payne’s Gray is a classic color made with Ultramarine Blue and Ivory Back. It is essentially a more neutral version of Ultramarine. It can be used for skies, shadows for flesh tones, as an alternative to black and so much more. It is one of those colors that once it makes its way onto the palette, becomes universal and a frequent contributor to many mixtures. It is Semi-Opaque, fine, and dries within a couple days.” In 2023, Golden published groundbreaking new research on lightfastness and choice of mixing whites. The choice of mixing white may affect the performance of certain pigments. See https://justpaint.org/astm-lightfastness-testing-for-oil-paints/ for more information.