It is clear that humidification is not only necessary in autumn and winter.
If your company is not equipped with a thermo-hygrometer, you should still consider humidification whenever the following signs or situations occur during production:
1. When significant production issues or quality defects arise
This is the most direct indicator. If the workshop shows the following problems, it is highly likely that the humidity is too low:
Frequent static electricity problems (the most obvious signal):
· Material adhesion: Printing media (such as paper, PP, flex banner) stick together, leading to feeding issues, multiple sheets at once, or paper jams.
· Dust attraction: Printing media surfaces easily attract dust and hair from the air, causing white spots or defects on the final print.
· Operator shocks: Staff often feel electrostatic discharges during operation.
· Ink misfiring: Printed images show ghosting, blurring, or ink scatter due to static interference with ink droplet trajectory.
Abnormal ink drying:
A. Drying too fast (for water-based inks): Ink dries before fully leveling and absorbing, leading to:
· Increased risk of nozzle clogging due to ink drying on the printhead surface.
· Color shifts as pigments concentrate, resulting in darker or inaccurate tones.
· Misfiring from dried residues at the nozzle edge altering ink drop direction.
B. Drying too slowly (for UV inks on non-absorbent substrates): Although UV inks cure with ultraviolet light, excessively low humidity can reduce ink leveling before curing. Conversely, overly high humidity can cause condensation on substrates, weakening adhesion.
Material deformation:
· Mainly paper-based media: In overly dry environments, paper loses moisture, shrinks, or curls, resulting in:
· Registration issues: Inaccurate color alignment during multi-pass or multi-color printing.
· Wrinkling: Uneven media surfaces can scratch the printhead or cause wrinkles, leading to head damage and print defects.
2. Preventive humidification driven by environmental conditions
Proactively controlling humidity before problems occur is a more advanced management approach. Humidification should be considered in the following conditions:
Seasonal dryness:
· In autumn and winter, especially in northern regions, air moisture is low. Indoor heating raises the temperature but sharply reduces relative humidity (sometimes below 20%).
Continuous air conditioning:
· Most air conditioning systems dehumidify while cooling, causing sharp humidity drops. A 24/7 HVAC system must include a humidification module.
Geographic climate conditions:
· Workshops in dry inland areas (e.g., Beijing, Xi'an, Urumqi) require year-round humidification more than coastal humid regions (e.g., Shanghai, Guangzhou).
3. Humidification required by specific production processes
Certain production scenarios have strict humidity requirements:
When using static-sensitive substrates:
· Such as PET, PE, PVC films, premium photo paper, or synthetic paper. These materials generate static easily and require higher humidity (50%–60%) to prevent static buildup.
During high-precision printing:
· For fine art reproduction, premium photo printing, or proofing, where color consistency and detail accuracy are critical, stable humidity is essential.
When using specific ink types:
· Water-based inks: Most sensitive to humidity; require humidification to prevent nozzle drying.
· Latex inks: Their curing involves heat and ventilation, which can dry the environment, so humidity control is also important.
Tip:
Equip your inkjet printing workshop with an accurate thermo-hygrometer and include it in daily inspections. Maintaining the environment within the ideal range of 20°C–25°C temperature and 40%–60% relative humidity will minimize production issues caused by environmental factors and ensure consistent, high-quality printing results.
