Your brand blue looks sharp on screen. Then the custom boxes arrive, and it looks noticeably duller. The artwork may not have changed, but the selected color model and printing conditions can change its appearance. Such problems begin with how color moves from a screen to the printing press. While screens use light, packaging inks reflect light from the printed material, which affects the final result.
Screens display RGB color, while most full-color packaging printing uses CMYK inks. Understanding CMYK vs. RGB vs. PMS helps you select suitable colors, prepare artwork correctly, and approve a realistic proof before paying for a full production run.
What Is CMYK Color?
CMYK stands for cyan, magenta, yellow, and key, with the key plate typically printing black. These four inks form the basis of process color printing. CMYK uses a subtractive model. Inks absorb parts of the light falling on the packaging and reflect the rest toward your eyes.
Cyan mainly absorbs red light, magenta absorbs green, and yellow absorbs blue. Combining real cyan, magenta, and yellow inks produces an imperfect dark tone. Black ink adds depth and keeps small text sharp.
Process printing builds images with tiny halftone dots. When viewed at a normal distance, the dots blend visually into photographs, gradients, and different shades.
CMYK values are expressed as percentages. A black defined as C0/M0/Y0/K100 uses only black ink. A rich black combines black with other process inks for larger dark areas. CMYK is a four-color printing method widely used for commercial packaging.
CMYK packaging printing works well for colorful illustrations and product photography. The final appearance still depends on the press, ink, material, and printing conditions.
The material makes a difference. White coated board and brown kraft can give the same artwork noticeably different results. Share the stock and planned varnish or lamination with your printer early.
What Is RGB Color?
RGB stands for red, green, and blue. It is an additive color model used by digital displays: combining more light makes colors brighter. Some bright RGB colors cannot be reproduced by a CMYK printing condition, so they may appear duller after conversion and printing.
At maximum channel values, the combination produces the display’s white. At zero, it produces black, although the appearance of black depends on the display technology and settings. In common eight-bit files, each channel runs from 0 to 255. RGB(255, 0, 0) represents red; RGB(0, 255, 0) represents green; RGB(0, 0, 255) represents blue. Web designers also use hex codes. For example, #FF0000 is red, #FFFFFF is white, and #000000 is black.
RGB suits website graphics and product previews. It is the standard color model for digital advertising and screen-based content. Formats such as PNG, JPEG, GIF, SVG, and WebP commonly carry RGB content, although a file extension alone doesn’t establish its color setup.
A printer can accept RGB artwork through a managed workflow. The values still need conversion into the printer’s available colorants. Ask who handles that conversion and which profile they use. Adobe explains this conversion process.
What Is PMS Color?
PMS stands for the Pantone Matching System. It gives designers and printers named color references that are more useful than instructions such as “make it a warmer red.” In conventional spot color printing, the printer mixes an ink to a formula and runs it through a dedicated station.
That ink can print solid areas or screened tints. This differs from building the same shade through overlapping CMYK dots. Spot inks can also achieve certain colors and effects that ordinary process inks cannot reproduce.
Think of Coca-Cola red or Tiffany Blue. Their recognizability explains why brand color specifications matter. Use the brand owner’s approved standard rather than guessing a Pantone number from a screen.
Cost depends on the design. A simple logo printed with one spot ink may be economical. Photographic artwork using CMYK plus two spot inks needs additional press capacity and setup, so compare both options in your quote. PMS supports consistent color matching, but paper, ink coverage, finishing, and press conditions still matter. Agree on an acceptable color tolerance with your supplier.
Coated vs. Uncoated Pantone Colors
The C in Pantone 185 C refers to its appearance on coated reference paper. The U in 185 U refers to uncoated reference paper. These suffixes describe how the color is shown on different reference papers; they do not automatically mean two different ink formulas. Absorption and the paper surface change how the ink looks. Pantone explains the difference.
Brown kraft adds its own color, while clear or metallic films behave differently again. Request an ink sample on your actual packaging material before approval.
RGB vs. CMYK vs. PMS at a Glance
The table below compares RGB, CMYK process color, and PMS spot color. RGB is intended for screens, while CMYK and PMS are used in packaging printing according to the artwork, press, substrate, and color requirements.
| Factor | RGB | CMYK | PMS spot color |
| Creates color with | Light | Four process inks | Dedicated mixed inks |
| Typical use | Digital displays | Photos and colorful artwork | Critical brand colors |
| Main consideration | Screen and profile differences | Press, profile, and material | Ink target, material, and tolerance |
| Production role | Converted for print | Process separations | Separate ink channels |
A PDF, AI, or EPS file can contain different color types. Check the actual swatches, profiles, and separations before treating artwork as ready for press.
Why RGB Colors Change in CMYK
A color gamut is the range a system can reproduce. Some vivid screen colors fall outside the gamut of a particular CMYK printing condition.
During conversion, color management maps those values into the destination gamut. Saturated blues, greens, and purples may lose brightness or change appearance. The outcome depends on the profiles and conversion settings.
Ask your manufacturer for its artwork requirements and ICC profile before designing. Set up print artwork accordingly, keeping managed RGB images where the agreed workflow allows them.
Use soft proofing on a calibrated monitor to preview likely changes. Then approve an appropriate physical proof, since a screen cannot fully represent paper texture or reflective finishes.
For a spot color, ask about an ink drawdown: a sample of the proposed ink applied to the intended material. Check whether your proof reproduces the actual spot ink or simulates it with process colors.
Choosing Colors for Different Packaging Formats
Review samples under consistent lighting and agree on which approved reference will guide repeat orders. If a critical logo color cannot be reproduced well in CMYK, discuss adding a PMS spot ink. That may require an extra plate or station and affect the quote. Choose the color method according to the packaging format, printing process, material, and required color accuracy.
Corrugated Shipping Boxes
Flexographic presses use flexible plates to print on corrugated liners. They can run spot colors or process artwork, depending on the equipment.
Direct digital printing avoids printing plates and can suit smaller custom mailer orders. Ask how the printer simulates Pantone colors with its available inks.
Folding Cartons and Rigid Boxes
Offset lithography is widely used for larger runs of folding cartons and printed wraps applied to rigid boxes. A suitably equipped press can combine CMYK artwork with dedicated spot inks.
Flexible Packaging and Mylar Bags
Flexography and rotogravure are common choices for printing flexible packaging such as pouches, Mylar bags, roll stock, and labels. Gravure transfers ink from engraved cylinders.
Clear or metallic films may need an opaque white layer beneath selected artwork. Confirm the ink sequence, white coverage, and finished appearance with your supplier.
Prepress Checklist for Custom Packaging
Before sending artwork, check these details. At NexGen Boxes, our prepress team reviews custom packaging artwork for color setup, spot swatches, fonts, dielines, bleed, image resolution, and export settings before production.
- Color setup: Follow the manufacturer’s profile and conversion requirements. Identify any colors that shift during proofing.
- Spot swatches: Preserve agreed PMS colors as spot separations. Avoid duplicate names or accidental conversion to process colors.
- Small black text: Usually use C0/M0/Y0/K100 to avoid colored registration fringes. Confirm barcode requirements separately.
- Large black panels: Use the printer’s recommended rich black. C60/M40/Y40/K100 is one example, not a universal formula. Stay within total ink limits.
- Fonts: Embed fonts in the production PDF or outline them when requested. Outlining prevents font substitution; it doesn’t correct press registration.
- Dielines: Separate cuts, creases, and technical marks using the supplier’s naming rules. A spot swatch alone doesn’t make those lines nonprinting.
- Final export: Use the requested PDF preset, bleed, image resolution, and overprint settings. Inspect output separations before approval.
Keep an editable master file before outlining text or converting colors. That way, a product update or supplier change will not force your designer to rebuild the artwork from scratch. Technical production elements can be identified separately from printed artwork.
Get Your Packaging Colors Ready for Press
Use RGB for digital presentation, CMYK for process artwork, and PMS spot colors where the job needs dedicated inks. Agree on the material, proof, and color target before production.
NexGen Boxes can review your dieline, color profile, and ink requirements. Send your artwork, packaging specifications, and order quantity for a prepress review and custom box quote. Our packaging designers can help you select the right color setup for custom and bulk box orders.
Frequently Asked Questions
What happens if I print an RGB file?
An RGB file can be printed when the printer or RIP converts its values into the available output color space, commonly CMYK. Bright RGB colors may shift, especially neon greens, vivid blues, and saturated purples, so approve a soft or physical proof before production.
Can you convert RGB to CMYK without losing color?
Not always. If an RGB color falls outside the CMYK gamut, conversion must replace it with the closest reproducible color, which can reduce brightness or saturation. Use the printer’s ICC profile and proof the converted artwork before approving the full packaging run.
Why does my blue look purple when printed?
A screen displays blue using RGB light, while printing reproduces it with ink. If the original blue is outside the CMYK gamut, conversion, color profiles, ink density, paper stock, or the CMYK mix can shift it toward purple. For a critical brand blue, specify a PMS color or approve a physical proof.
Should packaging artwork be in RGB or CMYK?
Packaging artwork is typically prepared in CMYK when the job uses process printing, while PMS spot colors can be added for specific
