Viscosity is absolutely critical to inkjet printing.
To get the best performance from an inkjet printer, the viscosity of the ink must be maintained in a specific range. If the viscosity is too high, the ink will clog the jets. If the viscosity is too low, air will backup into the jets - causing dropouts. By keeping the viscosity in the right range, you should get the maximum density - without any runs or dropouts. That means, using a Vutek cup, it should take 60 seconds for the cup to empty.