Check out Steve Anchell's excellent book on VC printing; it will save you a lot of time and help you to understand how VC papers work. VC filters work by varying the proportions of green light and blue light. Most filter sets use the subtractive color method (yellow subtracts blue and magenta subtracts green). However, you can also use the additive color method: green filter for low contrast and blue filter for high. One can also mix and match subtractive and additive methods and create your own filter set.