He also painted a related series with secondary colored dots on white fields, and a smaller group with gray dots on white fields. (ronnielandfield.com)
I've used black, white, grey, and navy / denim for the neutral base, and I've added some blue and olive as secondary colors. (unefemme.net)
If you choose to use primary colors, they can also experiment with mixing the colors together to create secondary colors. (viewsfromastepstool.com)