http://3.bp.blogspot.com/-AncTr9W5oqY/VGwZLiAhRAI/AAAAAAAAB4E/NQ3gFrPt_0E/s1600/39%2BP17%2BDe%2BAtramentis%2BB%2BM.jpgThis isn't just one recipe but I thought it may be more useful to see them all together. Document Blue and Document Magenta in the ratios written below make gorgeous waterproof, lightfast purples. I'll post the cyan and magenta in a new topic.
http://4.bp.blogspot.com/-A_ZJrTOWEYs/VGwZOgu2IwI/AAAAAAAAB4Y/r0IfLv8Xj3Y/s1600/39%2BP17%2BDe%2BAtramentis%2Bmixes%2BC%2B%2BM.jpg These mixes actually create a Document Blue hue, but also a lovely range of waterproof, lightfast purples.