04/19/2016 - Technical focus
POLYESTER LITHO PLATES
JS litho polyester plates have excellent lithographic properties. The imaging side of the plate has a matte, toothed surface, similar to that of a finely ground stone. The coating on the plate is extremely hydrophilic and retains water which rejects the printing ink in the non-imaged areas of the plate. It is the imagery created with a variety of waterproof media that accepts the ink. The plates are not light-sensitive, and if kept clean and dry, have a virtually unlimited shelf-life.
This kind of plates was designed to allow imaging directly from laser printer to plate. Plates should be cut to the size capacity of the laser printer. Plates are capable of extremely fine resolutions. 1200 dpi (dots per inch) will provide a screen ruling of 100 lpi (lines per inch) and 65 gray levels. Output at 1800 x 1800 dpi will provide 196 gray levels at 100 lines per inch. Once output, the plates can be printed directly.
A wide variety of drawing media can be used directly on the plate. Basically, any water-proof material that will bond itself (or can be heat bonded) to the plate will work. Try drawing with pen & ink, ballpoint pen, markers, and by all means experiment with any water-proof medium you can think of.
It is essential that the image areas be bonded to the surface. In some cases a too fast laser printer may not sufficiently fuse all particles to the plate. In most cases printers that output at 4-8 pages per minute provide the optimum fuser time. If the toner is coming off the plate during wetting or roll-up, the toner needs to be manually fused. This can be done by heating the plate to about 180 °F ( 82°C), (temps above 200°F ( 93°C) may begin to melt the plate). Similarly, drawing with dry toner or toner washes can be manually fused.
Dampen the plate, roll-up with standard litho ink and print. Plates can be printed on a hand litho-press, an off-set press or an intaglio press.
Goodluck for you work on litho polyester plates!
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