I think you entirely missed the point ic-racer, dialing in the same filtration with all 3 filters gives ND. A technique used in many colour labs is to add a set CC to each colour channel as ND filtration when times are too short.

Quote Originally Posted by ic-racer View Post
If you are using graded paper, you can remove blue light by dialing in yellow filtration. A very rough guide is 30cc per 'stop' of exposure.
That then drops the contrast as well.

If the contrast filtration required is say 15m then adding 30 to each filter ie - 30y 45m 30c, gives a reasonably ND effect.