Defining and Achieving Standards Technical Pre-Press Summary Copyright Germinate Ltd. ©

A note from the inventor “As the inventor of a process that enables printers to standardise their printing, across all of their presses, it is logical to ultimately reflect upon printing and proofing standards.The technology represented in Press Signature allows us to scrutinise the printed result, as if using a giant magnifying glass, and to fully understand the things that affect the final result. The key point of this new technology is not to change how hard we work, but to improve the quality of our print and to provide help and knowledge when things go wrong. ” Mark Priest Inventor

Proofing Standards Printers usually match the proof to the press Proofing devices vary Pigmentation in inks and dyes vary Presses rarely have true grey balance

Problems With Colour Management Test forms often complicated & difficult to print Expensive Does not show if there are any press related problems Often produces an unsatisfactory result with a short lifespan

Colour Management Requirements Press stability (repeatable results) Uniform printing conditions Ink pigmentation Predictability (control)

What is an unstable result?

What is a stable result?

Problems associated with fingerprinting Measurement results often inconsistent Curves may contain visible bumps, that are caused by the way light reflects back to the densitometer Even using the smoothing tools in the RIP corrections may still create hue shifts and have short life spans Still does not show if there are any press or pre-press related problems

Four colour dot gain curves, (% dot area - value on plate)

A curve fitting algorithm

“A software application was built around the curve fitting algorithm.” The program uses densitometer measurements taken from a step wedge that is placed in the trim area, or gutter of the job.” Press Signature was born… N.B. Various sizes of step wedge available, to suit densitometer used; (shown approx. 3mm x 120mm)

What is standard dot gain? “ISO Contour Curves were re-created as a selection of standards within Press Signature. The fit to these derived dot gain standards is extremely close, less than 1% difference, which enables a good comparison to any printed sheets. The interesting point is that the characteristic shapes of each are predominantly caused through the plate making process.”

Right: ISO Curves A to D Left: ISO Curves E to H

Dot loss from positive film generated plates We can see that the signature shows a dot loss in the quarter- tones. A typical transfer curve shape is usually more symmetrical

Transfer curves from the same press, using CTP plates As we can see “linear” CTP plates produce a fuller result

The differences in transfer curve from CTP to Film Result from positive film Typical result from CTP plates

How to analyse your press Place step wedge on job Print to required densities Read printed step wedge with any densitometer Enter into the Analyser application Click on the “Red Cross”

Click the red cross to analyse the “signature” Click here to analyse your press There are various tests for each press type

What does it check for? Grey balance and consistency of printing units Press stability and mechanical slur Incorrect blanket packing or cylinder pressure High and low dot gain Dot loss from film to plate and plate wear Web tension and sheet travel

Identifying mechanical faults “The following slides show a mechanical slur fault on a sheetfed press. You can see that the black curves are completely different to each other. A pre-press correction would not cure this problem.”

The slur test is active with two or more sheets Slur test results will help you locate the problem

Repairing mechanical faults “The following slide shows a mechanical slur fault on a multi-deck web press. You can see that the cyan appears to be rocking from side to side. Analyser can be used to identify a problem then confirm if the repair made by the engineer has resolved the problem.”

The cause of this slur proved to be a loose drive belt This is slur on the Cyan

Two sheets are entered to check the repair

Each stack or tower or press is checked for stability

The procedure is repeated for all towers

All towers are stable… …but print differently

Physical adjustment of press characteristic “With all stacks of the web press stable it is now time to create a pre-press correction. A file is created containing one sheet from each stack; this would be the same strategy if you had several sheetfed presses. The results are compared and physical changes are made where possible.”

There is too much difference between these black units

These three units are closer but still 5% apart

A correction from Corrector will “split the difference”

This yellow is actually quite high but the three are similar

Cylinder pressures & packing corrections “More sheets are printed to check the result. In our case study this whole operation probably would not have been possible, without Press Signature Analyser”

After adjustments all three cyan dot gains are within 3%

The magenta is very good, two curves are almost the same

This yellow ink is producing very high dot gain

The black units are now much closer to each other

The black & yellow inks have significantly higher dot gain These two curves should have similar heights to the other inks

The final result after corrections are applied into the RIP If a profile is created from a target printed in these conditions, it will produce the best result possible

Colour Gamut Comparisons “The IT8 target was printed through the new calibrated set-up. The big advantage, is the correction for the press can be updated when the press changes, without having to print another IT8.”

Please observe the bumps in the “tone curves” created from the measurements of the profile target

This file was also produced from the measurements Note: There are no bumps to smooth out when you use Press Signature

The IT8 report as spotted that the Delta E value is noticeably different. (both Black & Yellow inks)

Advantages to the process Identifies problems that affect stability Produces repeatable printing conditions Standardises the printed result Only one ICC profile is required from one press per stock all other presses are calibrated to match Allows use of generic profiles across multiple printing plants, publishers, designers, agencies……

Executive Summary “The following slides will help the financial executive identify appropriate return on investment figures and justify the capital expenditure to improve the manufacturing process.”

Improve Productivity When plates are calibrated to the press, press men are effectively forced to print at the manufacturers recommended ink film thickness, when matching a proof This produces the fastest make-ready because ink weights are standardised from job to job. This also avoids most of the problems associated with ink water balance, for example piling or emulsifying.

Divert jobs to any press Press Signature standardises the manufacturing process, enabling the printing of jobs on older equipment or even to utilise presses at other plants Makes staff responsible by enabling managers or group directors to view latest printing conditions of any press in any plant at anytime Re-assures customers of reliable standards of proofing and printing, (certification service through web)

Find and fix mechanical problems Identifies plate making problems such as dot loss and poor linearity Identifies problems that affect stability such as mechanical slur, which could be caused by gripper wear or faulty drive belts Links to world-wide-web for support database of press and pre-press related problems linked to curve statistics