Most of the time, the machines were/are designed and built around the ink and it's properties. Changing inks can many times create problems down the road for any number of reasons.
This is a subject that comes up time after time after time and again. How is it, that some part of your equation of making signs becomes such a major factor long after all the signs were made ?? If the ink cost is 13¢ or 15¢ a square foot, how is getting it down to 9¢ or 10¢ a square gonna make that big of a difference ?? If your purchasing/boss can't see the simple math there, unless you are going through a few thousand dollars of ink a week, gonna make a difference.... even if you were going through gallons of ink in a week ?? I mean, that'll make a sign cost $342.00 instead of $339.00. Will that make a big change in how you're doing business ?? If you are indeed going through as much ink as you claim, then, you are evidently doing something right..... so why change it ?? You could lose warranties, parts could wear out much faster and profiles will need to be sorted..... all to save pennies. Seems foolish.