Interestingly, the paints in the Portrait system include Neutral 3, 5, and 7. If there were neutrals 1, 2, 4, or 6, they appear to be hard to find. There are also Lights, Halftones and Darks in the Sanden System. As of this writing, these are available though Blick, though that may be only as supplies last. As of May 2023, the Portrait Institute posted the following on their site: “The Martin/F, Weber company, which existed for over 150 years, has gone out of business. They manufactured our colors since 1974. Parts of the company were purchased by Chartpak and they are in the process of manufacturing the Pro Mix colors again.”