The economics nobody runs
Roller cost represents less than 5% of what a given print run consumes in ink and paper. Yet rollers are the heart of the printing press, and neglecting them guarantees poor results across the other 95%.
Unless the rollers are in A-1 condition at all times, top quality printing is not only unlikely but impossible.
Successful printing depends entirely on the control of ink distribution. Proper rollers pick up an ink film and deposit the necessary amount for a correct impression. Hard, dry, cracked, dead or dirty rollers cannot. Tiny surface cracks or a hard glaze prevent the roller from holding ink and splitting the film — ruining even a superior plate, printing beautiful halftones muddy, and inviting waterlogging and stripping.
Proper selection
Roller types vary by function — ductor, distributor, intermediate, form. Selection depends on ink type, press speed, equipment and several other factors. Manufacturers continually develop new rubber and urethane compounds, which is exactly why consultation is worth the phone call: the right recommendation is a moving target.
Storage
- Store away from dampness, heat, sunlight and ozone from electrical equipment
- Support rollers only by the shafts, on proper racks
- Never let the cover contact anything that will cause a surface depression
- Keep rollers in a clean, dust-free location
- Rollers should be wrapped in paper or covered
Spare rollers
Hold roughly one quarter of a spare set per press. New or reconditioned rollers should go on immediately while the rollers coming off are cleaned and stored.
A new rubber roller may not be stress relieved and is apt to start developing high and low spots — which is the argument for rotation rather than for hoarding new stock. Store spares at normal room temperature on suspended journals, horizontally or vertically, with covers never contacting a surface. Rotate spares with press rollers at least every six months, and keep them covered.
Setting on installation
Set all rollers very lightly when cold, because frictional heat and ink absorption cause expansion in use. After 20–30 minutes of running, when the press has reached operating temperature, recheck and reset if necessary. The principle does not change: as lightly as possible, consistent with transferring ink.
Daily discipline
Check rollers daily to prevent accumulated ink and gum glaze. Stripping, streaking, hickies, emulsification, excessive plate abrasion, ink glaze and gum glaze all result from improper wash-up. Preventing build-up is far superior to attempting removal: glaze contains embedded pigment, wax, varnish, lint and fountain acid.
No roller can function properly if any part of its surface is clogged with dried oils, solvents or gum.
When surfaces become hard and glazed from accumulated dried ink, oils, solvents or gum, send the rollers back for reconditioning. Regular reconditioning maintains quality and extends useful life — it is a scheduled cost, not a failure.
