It might be because these points weren't done properly:
First, workshop temperature. When the workshop temperature drops below 18°C, the flowability of UV ink deteriorates, the printhead may experience minor clogging, and the print results may show streaking or ink misting. The solution is to turn on the workshop air conditioning in advance before starting the machine each day to raise the temperature.
Second, in winter, the ink becomes like syrup. When viscosity changes, color accuracy drifts. The solution is to use a temperature-controlled stirrer and test the ink viscosity before printing.
Third, materials. Sheets and glass just taken out of the warehouse have a cold surface. Printing directly on them will definitely compromise adhesion. The solution is to bring the materials into the workshop in advance and let them acclimate to the workshop temperature.
Fourth, workshop humidity. Winter air is very dry, which invites static electricity problems. Printing may experience ink misting. The solution is to maintain workshop humidity at around 50%–60% and run both humidifiers and static eliminators.
Fifth, machine maintenance. Since ink flowability decreases in winter, maintenance frequency should be increased. The solution is to perform the standard cleaning procedure every day before shutting down.
Sixth, ink curing. Because temperatures are low in winter, the ink does not cure easily. The solution is to increase the UV lamp power or reduce the printing speed to ensure the ink is fully cured.