Realistic simulation of ink overprint

Question

Hi all: I am an Illustrator and I screenprint my own works: I’ve been searching for a reliable way to simulate color overprints in PS but still no clue: traditional blending modes or fiddling with transparencies just don’t do the job: I have actually made a large set of test prints to actually compare real world results with my tests in Photoshop, with no consistent results up to now.

Someone tried to solve the problem here: https://prinfab.com/blog/simulating-a-screen-print-with-digital-print/

But that just does not work, in real world colors do not add up that way. Did anyone solved this before? Thanks]1

Answer 1

There is no magic silver bullet here. The appearance of two overprinting inks depends on many physical factors such as the absorption and diffusion spectrum of both ink, their opaqueness (also known as solidity), the absorption of the substrate, etc…

For non-opaque inks, a multiply blend (in RGB) gives a fair approximation in most cases. That is also how adobe tools simulate overprinting spot colors on screen (eg. In photoshop’s multichannel mode or illustrators overprint preview). But it is inherently inaccurate since all those ink properties are just not available in your design tools.

If you really need more accuracy without having to test every new combinations, then you have to look at the packaging industry where overprinting spot colors are common and color tolerances are tight. There are advanced color management solutions involving a spectrophotometer and test prints to model individual inks, as well as software to predict any combination of those.

Answer 2

In my limited experience multiply blending mode is one option to simulate stuff like duotones that will be printed in offset printing.

Is it accurate? It is good enough for me.

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Here is the catch or catches in plural...

It does not exist to my knowledge any color profiling of a random combination of direct inks, add that different inks with different transparency coefficient and paper absorption.

You are quoting a silk-based print where traditionally the inks are NOT transparent.

I am not sure about this, but I think even offset print spot inks has not the same transparency over process inks.

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I have only simulated duotones because I have indeed used them "a lot" (I am pretty sure more than most designers) on low-cost magazines, and we never expect an "accurate color" we expect good design and a nice look to it.

Here is an example.

Using a duotone was to save costs, but in other cases, the cost was first cut using lower quality paper, so, we never expected color accuracy.

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In your case, it is probably a good idea to invest some time in making your own tests and compare them with a printed result.

You can probably make a "profile" for example, using a duotone blending mode, and then adding an additional layer to simulate the "real" output, making it darker, or lighter or a bit unsaturated.

Answer 3

Have you tried it in Illustrator before? there is an option where you can overlay the different colors. Its called Overprint Mode