Rotary Letterpress
The invention of ultra-violet curing inks has helped keep the rotary letterpress alive in areas like self-adhesive labels. There is also still a large amount of flexographic printing, a similar process, which uses rubber plates to print on curved or awkward surfaces, and a lesser amount of relief printing from huge wooden letters for lower-quality poster work.
Rotary letterpress machines are still used on a wide scale for printing of self-adhesive and non-self-adhesive labels, tube laminate, cup stock, etc. The printing quality achieved by a modern letterpress machine with UV curing is on par with flexo presses. It is more convenient and user friendly than a flexo press. Water-wash photopolymer plates are used which are as good as any solvent-washed flexo plate. Today even CtP (computer-to-plate) plates are available making it a full-fledged, modern printing process. Because there is no anilox roller in the process, the make-ready time also goes down when compared to a flexo press. Inking is controlled by keys very much similar to an offset press. UV inks for letterpress are in paste form, unlike flexo. There are various manufacturers of UV rotary letterpress machines, viz. Dashen, Nickel, Taiyo Kikai, KoPack, Gallus, etc. which also offer hot/cold foil stamping, rotary die cutting, flatbed die cutting, sheeting, rotary screen printing, adhesive side printing, and inkjet numbering. The central impression presses are more popular than inline presses due to their ease of registration and simple design. Printing of up to nine colours plus varnish is possible with various online converting processes.
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