Proofing For Screenprint On An Inkjet

One of the big pluses for inkjet imagesetting, besides being very economical, reliable, high quality etc. :-) is that you can use the same settings for producing proofs. Because they use the same settings they will have the same screening.

Inkjets use a contone screening which is not reproducible by screenprint (which uses halftones). Most RIPs either use halftones or contone (which give solid colour). You can't use both on the same image, for a 4 colour job with spot colour, either the spot colour will appear halftoned or all the halftones will be printed as contone tints. Spot colours cannot be matched by process (CMYK) colours - if they could - why use spots! Therefore the intention of the 'proof' must be clear, it is safe to halftone the image and use a disclaimer about spots. Spot colours are special inks and are less susceptible to variation.

Begin by setting up a four colour (CMYK) mode on the RIP, Lt Cyan/Lt Magenta/Oranges and Greens should not be used, these will interfere with the proof.

Produce a colour profile for the CMYK mode using the desired halftone screen. Screenprint inks are formulated to be close to Pantone CMYK inks, inkjet inks are brighter to allow more saturated colours and a wider colour gamut to be achieved.

The proof should be a reasonable representation of the final screenprint job.

The CMYK values of the colours on the proof will be different from those of the screenprint. 100% screenprint magenta may require a formulation of 90% magenta with a little cyan and yellow to match the actual colour.

The most important part of your proof may be your disclaimer.

By: David Foster

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David Foster has 22 years experience in the pre-press industry and specialises in sales & support of imagesetters for the UK screenprint market. For more information visit Positivity Limited.