From a customer question to a repeatable deposition test
The useful answer was not only the theoretical minimum. For the customer, repeatability was just as important as the practical minimum: the same very small amount had to be applied again and again under controlled conditions.
The challenge
The customer needed to understand both ends of the usable range: how little liquid could be applied in practice, and whether very small doses could still be repeated reliably instead of becoming a manual skill problem.
The setup
We used a CNC Singular X with Smooth Head and a 0.2 mm nozzle. The video shows four tests: flow with a very slightly opened nozzle, minimum amount deposited over an area, minimum amount sprayed into one point, and maximum flow with the 0.2 mm nozzle fully opened.
The result
The test showed a wide practical range between the smallest applied amount and the fully opened 0.2 mm nozzle. With a 0.5 mm nozzle the maximum flow would be significantly higher, although that variant is not shown directly in this video.
Why this matters
For expensive inks, reagents, coatings, or experimental liquids, a spectacular minimum is not enough by itself. The useful process window is defined by both controllable low-volume deposition and repeatability. The final result still depends on nozzle size, viscosity, pressure, stand-off distance, speed, substrate behavior, and drying time.