Direct humidification for reliable printing processes

Printing processes require correct air relative humidity control. In fact, the physical properties of paper are affected by its moisture content (g/kg), which in turn depends on the relative humidity (%RH) in the surrounding atmosphere and any variations over time (hysteresis).

Uncontrolled relative humidity levels can cause considerable dimensional variations, up to 2% in length, resulting in loss of flatness (puckering, warping) and loss of register, as well as variations in colour absorption efficiency (dot gain, doubling) and electrostatic problems (paper jam, blocking, ink mist).

Optimal humidity control depends on the type of material being processed and the printing process itself.

For printing on paper, raw material manufacturers test and guarantee the physical properties of the paper at 23°C and 50%RH, in accordance with the ISO-187-2022 standard.

Consequently, a lack of humidity control will lead to uncontrolled variations in the physical characteristics of the material, with a significant impact on the effectiveness of the printing process and the quality of the finished product.

Different printing techniques require different levels of relative humidity to ensure there are no quality defects and reduce the risk of machinery downtime. Furthermore, the rolls of paper need to be moved from storage to production taking into account the time needed for the paper to acclimatise, which may vary from a few hours up to 72 hours (for coated paper). It follows that continuous ambient relative humidity control brings clear benefits in terms of materials management, production logistics and finished product.


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humiFog for the printing industry

humiFog Multizone Touch is CAREL’s high-pressure adiabatic humidifier for precise and effective control of humidity in ducts and directly in rooms.
humiFog is the ideal solution for large humidification loads and multi-zone systems thanks to the wide range of sizes available, from 150 to 1350 l/h, and the ability to control up to 12 zones with independent humidity set points, using just one humidifier.
The version with oil-free, water-lubricated pump is the new addition to the humiFog family, the perfect solution for mission-critical industrial applications, which require continuous 24/7 operation and minimal maintenance.

One solution for the entire plant
• Paper storage humidity control
• Print shop humidification and evaporative cooling
• Dissipation of static electricity
• Dust suppression

Direct in-room 
• Stand-alone humidity control
• Ideal for retrofit


High capacity
Pumping station up to 1350 l/h and system with up to 12 independent zone


Minimum maintenance thanks to oil-free lubrication, up to 8000 operating hours

Hygiene requirements
Compliant with hygiene requirements
• VDI 6022-1
• VDI 6022-6
• VDI 3803-1
• SWKI VA 105-01
• ÖNORM H 6020