Hand proofing and bar proofing are the two most popular proofing practices currently applied by local printers. Hand proofing is a simple and durable method that comprises a rubber roll and anilox roll mounted in a frame. ‘The ink is applied to the nip formed by the two rolls and the proof is created by the operator pulling the hand proofer over the substrate at an even speed and pressure,’ explains Paul. ‘Changing the anilox volume or rubber roll durometer can alter the amount of ink transfer. However, owing to operator variations in speed and pressure, this method creates inconsistencies,’ he adds.
Another popular technique requires the use of a bar proofer, a mechanically-driven device that controls speed, pressure and ink film thickness. A wire-wound rod draws ink on to the substrate and the wire thickness determines the ink viscosity that’s laid down.
‘Bar proofers offer many advantages: they can be correlated to the print station and are operator independent, durable and easy to clean but, unfortunately, they often don’t lay down ink as smoothly as the press on uneven or highly-absorbent substrates; nor do they determine transfer differences,’ Paul advises.
Precise proofing
A reliable solution to bar proofing and hand proofing inefficiencies is the Perfect Proofer, from US-based Integrity Engineering, Paul maintains. It’s a laboratory-scaled flexographic proofing machine that simulates an actual print deck with an anilox, doctor blade, plate and impression cylinder and, in Paul’s view, represents the future direction of proofing.
‘The Perfect Proofer is a mechanical gear-driven device with precise impression settings for anilox-to-plate and plate-to-substrate,’ Paul comments. ‘Defined as an automated wet-proofing solution, it allows ink lab technicians to pre-flight ink formulations under actual press conditions. It can be customised to suit specific ink types and presses, including the same type of photopolymer plate, mounting tape, anilox screen and volume, drying and substrate used in a production environment. Impression pressure and nip distances are adjustable in small micron increments and some designs use photopolymer plates that can proof both solids and dots,’ Paul continues.
‘Overall, the Perfect Proofer generates accurate, repeatable results to within a fraction of a delta E, even matching the same dot gain achieved on-press, and provides significant improvements in cost and machine downtime compared to conventional proofing devices. By utilising this device, a lab technician can achieve colour perfection without the need for in-line colour re-adjustments, saving a minimum of 15 minutes per colour – typically the set-up period required using conventional hand or bar proofing methods. Ultimately, it boosts production up-time by hundreds of billable hours per week, and eliminates associated ink and substrate waste,’ Paul sums up.
For enterprises serious about cutting costs, improving quality and inspiring print innovation, contact CAE’s technical sales team for more advice on the advanced Perfect Proofer technology.
