glazing calander for calandrable water based varnishes SHINING LIKE A STAR The purpose of using a glazing calander is to increase the glossiness of the water-based varnish, as this is less shining than the consumers' expectation based on the other types of varnishes.
The polishing process takes place after application, generally by an offset press, of a primer for the preparation of the bottom of the sheet and then of a calandrable water based varnish in a quantity that varies, according to the type of substrate, between 3 and 5 gr/m2, taking care to leave an uncoated edge of 20 mm.
The stack of sheets is then moved to the glazing calender and fed by an automatic sheetfeeder with the uncoated edge as the gripper side. The sheets arrive at the calander unit automatically spaced from each other and with the coated side in contact with a cylinder being heated with diathermic oil at about 140°C and with a mirror finish surface, under which a rubber pressure roller will distribute pressure up to 140 Kg/linear cm.
The sheet will remain firmly attached against the chromed cylinder until the detachment takes place at about 200° of rotation of the cylinder through a powerful blow of compressed air that wedges under the uncoated edge of the sheet. After its detachment, the sheet continues its way to the automatic stacker on a vacuum and cooled carpet.
The chromed cylinder is kept constantly clean of any paint residues through special brushes.
The cleaning operation will lead to the opacification of the mirror surface of the calander after one year of use on two shifts and therefore our supply includes a second calander, to be used when it becomes necessary to re-chrome the calander into the machine. Once re-chromed, the calender becomes reusable for the future.
The above described process refers to an off-line calandering.
For those who do not already have a machine suitable for the application of primer and varnish, Ecosystem offers a complete configuration of coating & calandering in-line.