Avoiding Colour Mismatches

When creating new artwork or recreating artwork from an existing design, there are a few ways that colour mismatches can be avoided:

  • provide the printer with a previously printed sample so that they can match the colour;
  • use CMYK breakdowns for CMYK artwork only, do not pick a Pantone colour and rely on the CMYK breakdown to be identical to the pantone swatch book (or the values the customer has in mind);
  • make sure that the appropriate paper stock in the swatch book is chosen (i.e. coated, uncoated, etc) as the same colour can appear differently on various stocks and textures
  • when matching colours from a previously printed sample, be aware that embellishments such as gloss varnishes and plasticotes can make colours look richer than they were printed, and the opposite can be said for matt varnishes and plasticotes;
  • take note of the environment when colours are being chosen (e.g. a yellow cast from a light bulb causes colours to look differently);
  • never choose colours based on what they look like on-screen, as the RGB colour gamut of a monitor differs from the CMYK colour gamut of printing.

A little-known problem exists when clients choose a Pantone Colour and rely on the software’s CMYK conversion to be enough. The problem is that Quark Xpress’s version of the spot to process can be one set of values, while Adobe InDesign’s version of the same spot can be another set of values, or the printer’s RIP could have yet another set of values altogether for the same spot, or the RIP could  base it on LAB values which then get converted to CMYK. If near enough is good enough, fine… but if a customer stipulates how the colour should appear in process, use those values when preparing the artwork to begin with.

Registration Colour

Adobe InDesign, Quark Xpress, (the now defunct) Freehand, Corel Draw… any layout/design program worth its salt has a colour in the palettes called Registration. This colour cannot be deleted and will always be in the palette, but what is this colour?

Put simply, Registration is a special colour which will appear on every colour separation when the file is output to print. It is not black, it is not 100% Cyan 100% Magenta 100% Yellow 100% Black, it is its own colour called Registration. So why is this colour there?

Ideally, the only items which should ever be in Registration are prepress marks such as crop marks; score/perf/fold marks; or registration crosshairs. Nowadays in offset printing, most of these marks can be applied in imposition software such as Creo Preps or Dynastrip, and it is unlikely that the Registration colour should ever need to be used in Adobe InDesign itself.

However, problems can occur when the prepress marks are set using 100% Black, as this results in the marks only showing on the black separation and none of the other colour separations. This means that the marks will not appear on the Cyan, Magenta, Yellow or any spot colour separation – only the Black separation.

Because registration is specifically reserved for prepress marks which are applied to a layout, using it to colour lines, fills, type or imported art in a design will result in ink being on every separation, causing issues with misregistration; and also causing issues with ink density on the print to be excessive (making the paper to distort in shape).

Instead, if the design requires a “blacker than black” colour, use “Rich Black” which is 100% Black with a percentage of Cyan, Magenta or Yellow within it. It is safe to say that the print community is split on what this value is, but so far 30% Cyan, 30% Magenta, 30% Yellow and 100% Black have provided me with a consistent and pain-free Rich Black value to use.

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