Ink viscosity changes depending on temperature. Constant viscosity gives constant print results in terms of droplet size - and hence constant colour fidelity.
Correct ink surface tension is largely responsible for consistent wetting of the substrate with ink and for shaping the droplets.
Inks must have a stable composition and only contain particles of non-critical size in relation to the print head nozzles to eliminate any sort of trouble.
Ink must keep within defined tolerance limits until its expiry date. We run checks on back samples. This enables us to detect unexpected deviations, recall ink batches if necessary and proactively avert problems at the customer.
We have built our own test rig for reproducing colour accuracy and ink curing. Ink batches must have a ΔE00 value less than 1 to be in tolerance and cleared for delivery, because only then is colour accuracy guaranteed.
Every ink batch must cure under UV light efficiently and according to defined parameters.