I kept running into "now, if this were oils or watercolor...." . Painter's a wonderful program but digital is just not quite paint. Thanks for the link! I'm going to make note of those formulas.
Some programs are intellegent in the way that they mix like IRL paints do. http://www.artrage.com/ Artrage is a program that is written to SPECIFICALLY replicate traditional media, and apparently it's really close. I don't know cause tablets aren't enjoyable for me to use so I don't do digital art often, but my friend Hannah swears by it. It's cheep to buy the full version of it too in comparison to Photoshop too.