Does anyone know how to print a gradient that cannot be reproduced by using regular CMYK inks with spot colors? (offset printing)

Ric

Member
I am a print director working at a print company in japan. We sometimes use bright color ink(s) to supplement the color that turns out to be dull with the regular CMYK inks. This is not to use the ink(s) as a solid but as a supplementary color. For example, when an animation character wears a very bright and colorful costume, we add some neon pink or green inks to supplement those costumes because the regular cyan, yellow, and magenta cannot produce the intensity and clarity of the colors that you see on the monitor. Obviously, we subtract the regular cyan, yellow, and magenta by 20-30% depending on how dense we want those colors to be reproduced. In this case, the numbers of inks to be used are regular CMYK inks +neon green(spot color)+neon pink(spot color). The total is 6 colors.
This supplementing technique is quite common in Japan but I don’t see any information on the web outside of Japan. The use of spot color as solids is the only information that I can find.

If anyone knows about this technique, please let me know.
You can see what I am talking about from this link (example)

Thank you in advance.
 

gordo

Well-known member
I am a print director working at a print company in japan. We sometimes use bright color ink(s) to supplement the color that turns out to be dull with the regular CMYK inks. This is not to use the ink(s) as a solid but as a supplementary color. For example, when an animation character wears a very bright and colorful costume, we add some neon pink or green inks to supplement those costumes because the regular cyan, yellow, and magenta cannot produce the intensity and clarity of the colors that you see on the monitor. Obviously, we subtract the regular cyan, yellow, and magenta by 20-30% depending on how dense we want those colors to be reproduced. In this case, the numbers of inks to be used are regular CMYK inks +neon green(spot color)+neon pink(spot color). The total is 6 colors.
This supplementing technique is quite common in Japan but I don’t see any information on the web outside of Japan. The use of spot color as solids is the only information that I can find.

If anyone knows about this technique, please let me know.
You can see what I am talking about from this link (example)

Thank you in advance.

The greatest user of that technique in NA is Hallmark greeting cards and breakfast cereal boxes. Do you have a specific question about it?
 
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Ric

Member
Many thanks for your comment.
My main questions are: 1, how I can select an appropriate spot color ink(s) and 2, how to figure out how much I should decrease the amount of the regular CMYK inks that are printed under the spot color. (If the spot color is to be printed after the regular CMYK on the same run).

The reason behind this is that it is often the case that the selected supplementing spot color is not as effective as expected, making the area where the regular CMYK and spot colors are used duller and darker. Knowing that the more ink printed, the darker color becomes in CMYK, it is quite difficult to figure out how much I should decrease the regular inks before making physical color proofs.

As we know, the gamut of CMYK is much smaller(narrower) than the one of RGB, so if possible, I would like to try to enhance some colors (that cannot be produced otherwise with the regular CMYK inks) with supplementing spots color inks.

As I wrote previously, this technique is common in Japan but has really relied on each prepress operator’s own heuristic experience (some are good; some are not so good). So, I would like to learn more about it, if there is any website or books that explain this technique systematically, just so that I get consistent results.

I would apply this technique not only to illustrations (such as a greeting card or the example illustration I provided) but also to photography in general.

Thank you.
 

gordo

Well-known member
Many thanks for your comment.
My main questions are: 1, how I can select an appropriate spot color ink(s) and 2, how to figure out how much I should decrease the amount of the regular CMYK inks that are printed under the spot color. (If the spot color is to be printed after the regular CMYK on the same run).

You can create the separations for the "bump" colors manually or automatically.
If you do it manually it is best to run a press test using one image that has been separated using different parameters of under (the extra color) color removal. That way you have a printed guide for your press condition. Note that the separations would have a minimal black component - the opposite of typical separation profiles.
You can also do it fairly automatically using, for example, software like Touch7 from Color-logic ( Color-Logic | Touch7 )

Some notes:
CMYK inks formulated to wet trap - Spot inks are typically formulated to print isolated (dry trap)
CMYK inks are transparent - Spot inks are typically opaque
Fluorescent inks are typically weak in color and they do not halftone well - losing the effect
Sometimes fluorescent pigments are added to standard CMY inks (e.g Pantone's defunct Hexachrome process). Fluorescent Yellow is sometimes mixed with process yellow in newspaper work to overcome the grey paper color.

Here are some ink colors that are commonly used to expand the CMYK gamut in a 5, 6, or 7 color process.
Extended process colors Hi-Fi.jpg

So you need to work with your ink vendor to make sure that the ink is formulated for your application.
 
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Ric

Member
This is great! Thank you so much for all the information.
I’ve never heard of this type of application. It looks very convenient and surely makes us easier to predict any final outcome.
I’ll try to make a closer look.

Just a side note, H-UV presses have been becoming common in Japan (rare to find presses that take oil-based inks). Some advantages are no dry-down and efficiency (no need to dry) but one of the disadvantages is that it’s difficult to gain rich black and strong neon colors.

I am not sure if this is true in North America though.

Best regards,
 

gregbatch

Well-known member
Hexachrome became Indichrome (Indigo), with the addition of violet to the orange and green. Later, Pantone came out with Pantone XG (eXtended Gamut), also adding violet for 7 colors. Pantone has since dropped that line as well, but you might be able to find a used Pantone XG guide that gives the color builds for almost all of the Pantone colors, hitting about 90% with reasonable accuracy. Simple and you have real swatches to look at. Your ink company might even have some XG swatch books still around.
 

Ric

Member
Hi Greg, Thanks for the information. I just looked it up on the web and found an EXTENDED GAMUT COATED GUIDE. It looks very convenient. I'll try to find one in Japan.
 

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