Once in a while, even in the best-run printshops, production can go sideways, go south, foul up, mess up, screw up, and go wrong. When that happens a well run printshop turns to their "Golden Reference" as one tool to diagnose the problem and determine a solution. A Golden Reference typically it consists of a file, press sheets, proofs, plates, and documentation. It preserves a record, or "snapshot," of the prepress and print conditions when everything was working correctly. As such, when a problem occurs, the Golden Reference file can be rerun through the workflow and even on press if required. Comparing how the Golden Reference performs at each stage of the current process to the original can help isolate where the differences are and therefore reveal what may be causing the live job to go wrong. The Golden Reference is also useful for validating consumables - such as ink and plates – which may change from batch to batch. It is also useful as the standard by which new processes – such as a change in halftone screening, or a new ink type – can be compared and introduced.
Ideally, the Golden Reference test form should combine objective as well as subjective elements. Sometimes it's easier for evaluation if they are kept separate on the press form as in the sample above. Here are some suggestions for test elements you may want to include (click on image to enlarge).
Remember to make sure that, as much as possible, inline ink usage conflicts and/or influences should be avoided. Also remember that a test form like this should be run "to the numbers" - no proof should be anywhere near the press that runs it. The press operator should be instructed to achieve, as much as possible, the correct solid ink densities across the sheet and not try to make the images look "nice."
A - Standard color bar including targets for CMYK solid ink density, RGB trap, dot gain
B - Background 25C, 18M, 18Y gray with 25 K checkerboard. The primary function is to even out ink usage on press. Can also be used to check across the plate imaging consistency.
C - Solid bars of CMYK in line with the press sheet direction of travel to test solid ink density evenness around the cylinder.
D - Your standard profiling target.
E - CMYK step wedges used for building dot gain curves and ink performance curves.
F - Industry standard target.
G, H, I - Gray balance ring-around targets used to determine whether gray balance is being achieved at the required tone value combinations.
J - Gray balance targets.
K - Industry standard images.
L - Your standard images separated according to your specifications.
M - Image resolution test. The same image is sampled at 100, 200, 300, 400, 600 dpi to show minimum image resolution required for quality reproduction at your halftone line screen frequency. Also useful when changing screening type and/or frequency (lpi).
N - Max black/total area(ink) coverage target. Used to determine maximum TAC.