First, do not blindly mix different brands of ink. This is the most fatal and also the most common mistake. Don't think that just because they're all UV inks, you can switch them around freely. Different brands of ink have different chemical compositions. When two different brands of ink are mixed together, they can react and cure, directly clogging the printhead. How to avoid this: If you're switching brands, you must clean the system. If you want to try a new brand of ink, you must thoroughly and completely clean out the old ink from the entire ink supply system.
Second, do not top off old ink with new ink. Trying to save trouble can cause big problems. Even for the same brand and same series of ink, it is not recommended to pour new ink directly into an old ink bottle. The old ink remaining in the ink lines and printhead may have already slightly degraded or may have been contaminated with moisture and dust from the air. Mixing new ink with old ink essentially contaminates the entire batch of new ink, shortens the life of all the ink, and creates a hidden risk of clogging. How to avoid this: Follow the principle of "empty before refilling." First, use up as much of the old ink in the ink system as possible, then add the new ink, and perform several purges to ensure the ink being printed is pure new ink.
Third, do not neglect the filter — changing the ink but not the "kidney." The ink supply system has a filter, which acts like the kidneys for the ink. After extended use, the filter becomes saturated with absorbed impurities. If you only change the ink but forget to change the filter, the new ink will still be contaminated as it passes through the filter, and the filtration effect will be greatly reduced. Fine impurities will still attack the printhead. How to avoid this: Strictly follow the replacement interval recommended by the equipment manufacturer, or replace the ink line filter whenever you do a major ink brand change.
Fourth, test after changing the ink. After changing the ink, some operators see that there is ink in the lines and immediately start printing production. How to avoid this: After changing the ink, you must strictly follow the three-step testing procedure: 1) Nozzle test — print a nozzle check pattern to ensure every nozzle is firing smoothly with no broken lines; 2) Droplet compensation test — check that the droplet ejection statement is consistent to maintain print uniformity; 3) Color block test — print a standard set of CMYK color blocks and compare them with previous samples to check for obvious color shifts.