White ink flow. We can print 10 square meters at 100% ink droplets with fewer than 5 needle breaks.
Smoothness of CMYK and other colors. We can print 10 square meters at 100% ink droplet coverage with fewer than 5 nozzle failures.
How long can the printer remain idle before ink clogs all nozzles without cleaning? Requires over 0.5 hours.
How is white ink coverage at 60%, 70%, 80%, 90%, and 100%? Strong coverage is good; weak coverage is poor.
Does the white ink appear slightly blue or yellow? It should be pure white.
How flexible is the white ink when stretched? Greater flexibility is better.

Is the white ink grainy? A grainy texture is undesirable; a smooth, even finish is preferred.
White wrinkling or peeling is unacceptable; the surface should be fine and smooth.
Compatibility of white ink with film: White ink that works well with a wide variety of films is preferable; ink that only works with a few types of PET film is undesirable.