After the paper machine, the base paper is usually coated in a separate step. The ink receptive layer is applied on the top side of the paper, and another 'anti-curl' coating may be applied on the back side to avoid paper distortion after drying. Another visible effect is the 'memory of shape ' of the paper from the roll, which may lead to a curly aspect on a sheet of paper.
This curl is more pronounced on rolls aimed at large format printing, and delivered on a 2" or 3" core.
For the paper sheeting, the original reels of coated paper are unreeled on a sheeter with the help of specific devices which will apply a pressure on the side opposite to the curl in order to lay the paper flat again. The paper is converted into sheets based on DIN sizes, and wrapped.
Our papers are made from the best raw materials and carefully converted, but curl can still occur as a result of constraints from mechanical or temperature / humidity origin. Therefore, we strongly advise you to store our products in the original wrapping (box or bag) away from any source of temperature, and avoiding extreme dry or wet ambiance. The optimal storage conditions are between 20 and 50% relative humidity.
As far as the using conditions and the paper behavior are normal, we recommend you not to change the printing parameters, which have been defined with the ICC profiles for the usual printers.
When considering the rolls, the only possible action to address the curl issue, is to change the gap between the printing nozzles and the paper surface. This parameter can be modified by progressive steps in the printer driver. As the OEM settings on the gap adjustment can vary from a printer to another on the same type, you will have to evaluate by some preliminary print tests the reaction of the paper when printed in given temperature and humidity conditions.
A low level of humidity may induce an accumulation of electrostatic charges which can attract paper particles from the printer cutter area, and lead to unprinted spots or flakes afterwards. In this case, we advise you to install an air humidifier in the printing room.
For the case of sheets, we advise you to gently bend the paper toward the side opposite to the curl. Please pay attention not to mark or fold the paper surface, and always wear cotton gloves for any handling.