
by Melissa Donovan
Corrugated board is a finicky, porous material. Improperly maintained environments can reek havoc on it before, during, and after printing.
Above: DriSteem’s Adiatec high-pressure system cooling and humidifying a press room.
“Uncontrolled relative humidity (RH) levels in a printing facility can cause a range of issues that directly impact production quality, efficiency, and costs. Maintaining the proper RH balance is essential to avoid these challenges and ensure smooth operations,” explains David Baird, senior application engineer, DriSteem.
Naomi Cassidy, marketing manager, Condair Inc., states that “humidity—being either too low or too high—has a significant effect on the efficiency of printing processes and the quality of the finished product. Since paper is a very hygroscopic material, its moisture content will be directly related to the moisture content of the air.”
Correct humidity levels are maintained with the help of humidity control systems like steam generation, evaporative cooling and humidification, dehumidification, and water treatment.
What to Watch For
There are signs that help determine whether a corrugated printer is operating in a space with an incorrect humidity level.
Low Humidity
When an environment is exhibiting low humidity levels the printing material becomes dry and brittle as the substrate is losing moisture content.
Signs of dry, brittle substrates are shrinking or even curling at the edges, notes Cassidy. With low humidity, the material becomes “more susceptible to cracking or tearing during handling and printing,” explains Baird.
The drier air also enhances static electricity. This causes “sheets to stick together or misfeed in automated machinery,” says Baird.
“Excess static electricity is created when moving the paper along the surfaces of the press, which increases the chance of a printer jamming,” adds Cassidy.
Ink drying prematurely on press rollers or nozzles before it reaches the substrate is another sign of low humidity. “This reduces print quality, leads to inconsistent coverage, and often requires additional cleaning and maintenance of printing equipment, further delaying production,” shares Baird.
Also related to ink, low humidity may reduce the quality of the print by causing ink colors to appear more faded, adds Cassidy.
High Humidity
High humidity levels are indicated by ink drying too slowly and mold growth.
When ink dries slowly it may “cause smudging or streaks during printing or the colors to be overly saturated,” explains Cassidy.
“Prolonged exposure to high humidity can foster mold growth, contaminating paper stock, emitting unpleasant odors, and creating health hazards for workers. Mold on equipment can contribute to corrosion, reduced efficiency, and the need for costly repairs or replacements,” shares Baird.
Also, “at high humidity levels the paper can become warped, wavy, or curled, causing printing jams,” says Cassidy.
Off Base
Many corrugated printing facilities operate at the incorrect humidity level.
“I would say that the printing industry is one where improper humidity control has more visible and immediate consequences and that it is often a major consideration for large print shops. However, the importance of humidity is still becoming more prevalent and there are many cases where print shops are not aware of how much their processes could be improved by controlling humidity,” shares Cassidy.
Baird says heat generated from the many pieces of equipment in a building contribute to skewed humidity levels. “Many corrugated printing facilities operate at suboptimal humidity levels, often because the printing process adds heat to the facility’s air, impacting RH levels. High-speed presses and associated equipment, such as motors, rollers, and drying systems for solvent-based or UV-curable inks, generate significant heat during operation. Friction from high-speed printing and cutting, creasing, and folding processes further adds to the heat load.”
And it isn’t just printing and finishing equipment, even an HVAC system is at fault. “Facility HVAC systems, which are usually designed to circulate air, can inadvertently raise indoor temperatures further, particularly if they lack efficient cooling mechanisms. Seasonal variability compounds this issue, as warmer months can intensify equipment-generated heat,” shares Baird.
“Poor humidity control will cause lower yields, quality, and efficiency of the printing process. It will cause more paper to be damaged and wasted, distort or alter coloring, and increase maintenance to printers and other components of the printing line. It will also cause the drying of ink or glue to take longer or not cure properly at all,” says Cassidy.
Reaching an Ideal
There is an ideal RH level for a corrugated printing facility.
Baird says it is between 45 and 55 percent, as it helps maintain the substrate’s structural integrity while preventing static buildup and smudging.
Cassidy agrees. “I would say the most common RH designed for these spaces is 45 to 55 percent. The ideal humidity range for printing is 35 to 60 percent RH. With water-based ink, it is often recommended to be at the higher end of that range, about or just under 60 percent.”
Tools are available to find your current level and then adjust accordingly.
A humidistat is helpful, in that it will regularly report the current RH in a space, suggests Cassidy. “It is important to note that humidity will vary depending on location and time of year, as well as temperature of the space. Humidity will be lower during the colder months, and this is increased the higher the temperature is in your building.”
“Spot checks can be performed using hygrometers to determine the current humidity level in a facility. At the same time, continuous monitoring systems provide real-time data for more accurate and consistent tracking,” notes Baird.
Specifically, humidification systems can help achieve—and maintain—the correct RH in a corrugated print facility.
According to Cassidy, a common type of humidification system for print environments is misting using in-space spray heads, nozzles, and a high-pressure pump skid. The Condair ML Series direct room humidification system offers low operating costs, reduced cooling costs, and requires minimal maintenance. The systems can be combined or customized to fit multiple zones, high loads, many different room configurations, and applications.
“This system provides accurate humidity control, is easily retrofitted into sites that don’t have ductwork or plan on expanding humidity in the future, and has exceptional energy efficiency,” shares Cassidy.
Adiabatic—or evaporative—humidifiers are efficient solutions for print shops. “These systems utilize existing heat in the air to evaporate finely atomized water droplets dispersed by the humidifier. As the droplets are absorbed, evaporation cools the surrounding air, reducing the cooling load and delivering significant energy savings. This dual function of cooling and humidifying is particularly advantageous for print shops, helping to lower operational costs while maintaining optimal conditions,” says Baird.
DriSteem’s Adiatec high-pressure system combines evaporative cooling and humidification to meet the diverse needs of multi-zone facilities. By customizing humidity levels in different areas, the system provides targeted control that ensures ideal environmental conditions throughout the space. This tailored approach supports production consistency and enhances comfort and stability, benefiting both the workspace and employee well being.
The Adiatec high-pressure system is equipped with DriSteem’s Vapor-logic controller, which continuously monitors environmental conditions to adjust nozzle operation for optimal absorption and minimal water waste. Designed for seamless integration, the system is compatible with Modbus and optional BACnet or LonTalk protocols, enabling fast response times and tight control via building management systems.
Beyond Humidification Systems
Other ways to control humidity include using steam generation, dehumidification, and water treatment systems.
Steam units are common in printing environments. “These produce clean atmospheric steam either directly in the room or through the ductwork using either electricity or gas,” explains Cassidy.
The Condair EL Series uses electrode steam technology to achieve economic, simple, and reliable humidification for in-duct or direct room humidification. EL humidifiers offer unprecedented installation flexibility. They can be configured for both small and large systems. All EL humidifiers are completely packaged for installation ease.
The Condair RS Series provides pure, clean, atmospheric steam from potable or DI/RO water with high precision. With SSR heating element control coupled with a high precision humidistat, the RS Series can achieve +/-1 percent RH, perfect for humidity-critical applications.
The Condair GS Series is a gas-powered steam humidifier that is engineered to meet the highest standards of efficient performance with cost-effective gas operation. It is designed for ease of installation, adaptability, simplicity of operation, ease of maintenance and servicing, energy efficiency, cleanliness, and long-term reliability. GS Series humidifiers offer complete application flexibility to system engineers, contractors, and customers.
DriSteem also offers steam generation systems, including electric steam and gas-fired humidifiers.
Electric steam humidifiers, such as the RTS resistive electric humidifier, offers precise humidity control with easy installation and maintenance. Electrode humidifiers include the XT series, one of the most affordable humidification systems to purchase and install. The STS Humidifier is a steam-to-steam humidifier, which uses an existing boiler steam to produce chemical-free humidification steam, ideal for high-impurity environments. Finally, its GTS LX humidifier utilizes natural or propane gas to generate steam, providing energy-efficient humidification for large spaces.
Dehumidification systems are helpful as well. DriSteem’s Evair Dehumidifier RL Series is designed to remove excess moisture, helping to prevent condensation, mold, and mildew while maintaining optimal humidity levels.
Finally, water treatment systems aid in maintaining the proper humidity. DriSteem’s RO 200 and RO 400 series reverse osmosis systems provide high-purity water for humidification, ensuring efficient operation and equipment longevity. Pretreatment systems are designed to condition incoming water; they enhance the performance and reliability of humidification equipment.
Regular RH
Identifying RH in a print production facility is important—and maintaining it is even more so.
“By maintaining optimal humidity levels, corrugated printing facilities can protect the quality of printed materials, improve equipment performance, and minimize disruptions to production. Proper humidity control is essential for consistent results, operational efficiency, and long-term cost savings,” concludes Baird. IPM
Feb2025, Industrial Print Magazine