With the Eco-Mist system, paper curl, feed and delivery problems and other static difficulties are overcome; customers can achieve high quality work at faster machine speeds.
At Humideco, we have a thorough knowledge of the paper and printing industries and are familiar with the problems that dry air and fluctuating humidity cause.
Paper and board used in the printing industry is hygroscopic and will therefore lose, or absorb moisture until it reaches equilibrium with the conditions to which it is exposed. This change affects the fundamental properties of the paper, ie, its tensile strength, dimension, fold endurance and smoothness. When the relative humidity is low, usually in periods of colder weather, problems such as curl can occur; the edges of the paper throughout the stack will tighten as the fibres near the edge of each sheet lose moisture to the surrounding “thirsty” air, reducing the ability of the paper to pass through a press. To compensate for this, machine speeds have to be reduced, in order to complete the run.
Additional problems can also occur when the relative humidity is low. Where multi-pass work is undertaken, close register control is difficult to achieve when environmental conditions vary from day to day. Static electricity, generated through friction, cannot readily dissipate away through dry air, and can build to problem levels, causing sheet feed and delivery problems. Ink drying problems are also common where relative humidity levels are low.
These difficulties are often impossible to avoid simply by conditioning stacks prior to printing. The degree of humidity control required in each particular case will vary with the nature of the work being carried out and the difficulties being experienced, and their effects on production. Typically, a level of relative humidity between 50% and 55% is considered the optimum for lithographic printing.
