How to Prepare CMYK Colors for Packaging and POS Printing

Want the colors on your packaging or POS displays to look exactly as designed? In this article, we’ll show you how to properly prepare CMYK print files and what to watch out for with challenging shades – from black, gray, and white to gold and pastel tones.

Printing on corrugated cardboard and solid board has its specifics. You need to consider not only the base color of the substrate you’re printing on – most commonly white, brown (kraft), or black – but also its ink absorbency. Corrugated board is more absorbent, while smooth solid board absorbs minimally.

The final printed result may therefore look slightly different in practice than the digital design on your monitor. That’s exactly why we send you a physical sample before production begins, so you can see the final product with your own eyes and make any necessary adjustments to the artwork.

For optimal results, we recommend following a few basic rules that we’ve outlined in this article. Now let’s look specifically at how to handle the preparation of individual color shades.

Rich black in print: proven CMYK values and when to use them

Choosing the right black for packaging and display printing can be tricky. For standard body text and fine lines, pure K100 is usually sufficient, but for larger solid areas you need to add other shades to make the color truly rich.

For larger areas, banners, or printing on darker substrates, rich black is better as it adds depth and saturation. If your design predominantly features cool or warm colors, you can choose a cool or warm black to better harmonize with the surrounding graphics.

Overview of the most common black variants in CMYK

• Standard black – regular black for text and thin lines; may appear slightly grayish on large solid areas
  • CMYK: C0 | M0 | Y0 | K100

• Rich black – a balanced, saturated black for solid areas, backgrounds, and larger elements; the universal choice for most cases
  • CMYK: C40 | M30 | Y30 | K100

• Cool black – black with a blue cast; suits blue and neutral palettes, modern layouts
  • CMYK: C60 | M0 | Y0 | K100

• Warm black – black with a red undertone; harmonizes with warm, golden, and natural tones in graphics
  • CMYK: C0 | M60 | Y30 | K100

• Super black – a very rich mixture for demanding areas, only for certain substrates and technologies
  • CMYK: C63 | M52 | Y51 | K100

• Registration black – only for registration marks, never use in regular graphics
  • CMYK: C100 | M100 | Y100 | K100

50 shades of gray? Gray for printing on corrugated and solid board

Gray is one of the most complicated colors to print. Its final appearance is affected by the substrate type and its absorbency, the printing technology (digital vs. offset printing, for example), and the specific press settings.

The substrate color also significantly affects the final look of graphics with gray tones – on brown kraft board, expect gray to appear darker with a warm undertone. On dark substrates, you need to use multi-pass printing or a white underbase. The following methods are most commonly used for printing gray:

1. Gray built from four CMYK colors

A gray shade is created by combining all 4 CMYK color channels – cyan (C), magenta (M), yellow (Y), and black (K). A popular variant is the so-called “rich gray” – CMYK: C2 | M2 | Y2 | K40–70 depending on the desired saturation.

• Advantages: Ability to adjust the tone to warm/cool variants, more even printing on larger areas, smoother gradients

• Disadvantages: Because it’s built from four colors, color shifts can occur during printing (monitor vs. actual print), so it’s advisable to make a physical sample before full production.

2. Gray created using only black ink (K)

A simpler way to print gray shades is to set them only in the black channel (K). Keep lighter and medium shades in the K10 – 50 range, and darker, nearly black variants between K 60–90.

• Advantages: Stable and solid color without risk of shifts between press sheets, sharp text, thin lines

• Disadvantages: On large areas it may appear flat or uneven, more suitable for small elements and smaller areas, issues on absorbent surfaces

Keeping white truly white – how to properly prepare white ink for print?

In standard CMYK, white is not printed; it’s an empty area where the substrate shows through – usually white board or cardboard. However, there are situations when opaque white ink needs to be printed, especially on dark or transparent substrates. How to do it right?

When is white ink used?

• Printing on colored substrates (e.g., black, kraft, or colored board) – here white is used as a spot color or as an underbase for other colors that wouldn’t otherwise stand out.

• Printing on transparent or metallic substrates – primarily as an underbase layer for other colors, standalone usually in multiple passes.

• Special effects – multi-layer printing for 3D effect – more often as a spot color, can also be an underbase

How to set up print files for white ink

• Standard white in CMYK – if you’re printing on white substrate, you don’t need to add white ink to the design – it will automatically be treated as an empty area. Simply leave white elements as C0 | M0 | Y0 | K0 (knockout).

• White as a spot color – standalone white should be prepared in the artwork on a separate layer (ideally only vector shapes without transparency or other effects). If it’s to serve as an underbase, you must precisely define the area where white will be applied (it doesn’t have to be the entire print area).

Special shades and effects – achieving rich colors, simulating metallic gold or spot varnish

1. Pastel colors

Pastel shades in CMYK printing can be less saturated than they appear on screen. We recommend adding a white underbase when printing on colored or kraft substrates to make the color pop. Pastels can also be affected by paper texture – matte surfaces often absorb more ink and naturally dull them, while gloss surfaces enhance them. Very delicate shades stand out best on printing technologies that work with spot colors.

2. Dark shades (navy blue, brown, rich black…)

For rich dark colors, we recommend adding a small percentage of black (K) to make the color fuller. For black ink, use the appropriate variant based on the graphic type (see previous section on black). Always verify the final effect on a physical sample of the packaging or at least a print sample.

3. Simulating metallic gold print

By correctly mixing CMYK values, you can successfully simulate a gold shade for a fraction of the cost of real metallic printing. The gold effect is created using a mix of yellow, magenta, and a small addition of black in various ratios (depending on the preferred warmth). A gradual gradient between shades directly in the artwork works very well. We also recommend shading to enhance the dimensional impression.

Recommended shade range for testing: C0 | M25–35 | Y80–90 | K5–15 (results will vary based on substrate and press).

Keep in mind that it’s still a simulation and any CMYK shade will never fully replace a real metallic effect. We do not recomennd simulating silver print; the resulting output almost always looks like a cool gray.

4. Black print on black substrate – spot varnish effect

Digital printing with black ink (K) on black board, when properly set up, can create a beautiful simulation of raised spot varnish for the price of standard printing. The naturally glossy surface of the print contrasts with the more matte substrate, and if multi-pass printing is used, the effect is even more pronounced. For this purpose, we recommend using rich black (CMYK: C40 | M30 | Y30 | K100).

Need help preparing artwork for packaging and display printing?

Want to be sure the print matches your expectations? Have a sample made before printing the full run and test the final colors directly on the chosen substrate. If you need advice on setting up shades or with the artwork itself, don’t hesitate to contact us – we’re happy to help!

You can also use the services of our graphic designer, who has extensive experience with print preparation and packaging design.