Greetings. For the office and use on cheap photocopy paper I like the quick drying properties of Noodler's Bernanke inks. Color selection is limited to red, blue or black. Here is my go at mixing the three colors to get new options including purple (1 part red to 1 part blue) and my general go-to color: blue-black or midnight blue.
Drying time seems to remain the same and not changed by mixing (but will leave it to others to test and confirm).
I've read mixing inks made by different companies can be problematic. My assumption (right or wrong?) is mixing inks within the Noodler's Bernanke family should be okay.
(Tests done on old (1940s-1950s) good stock graph paper)