What is CMYK – white – CMYK printing and what is it used for?

CMYK – white – CMYK printing is a multilayer printing technique most commonly used when printing on transparent or colored materials (e.g., clear film, glass, plexiglass, metalized labels, non-white plastics, lacquered metal, and even wood).

What does it mean exactly:

CMYK – the standard set of four printing colors: Cyan, Magenta, Yellow and blacK.
It is used to create full-color images.

white – an additional layer of white ink (or white toner/UV ink), printed underneath or in the middle.

CMYK (second layer) – another full-color layer printed on top.

Process:

1️⃣ First, the color layer (CMYK) is printed.
2️⃣ Then a layer of white ink is applied over it.
3️⃣ Finally, another CMYK layer is printed on the top.

What is it used for?

Increased intensity and contrast:
On transparent or dark substrates, colors alone would appear weak; the white layer acts as a base coat.

Double-sided effect:
For example, window decals that must be fully visible in color from both sides (you see CMYK from one side, CMYK from the other, and a white layer in the middle to prevent colors from showing through).

Blocking transparency:
The white layer makes the printed image more readable.

How do we use it in advertising?

Printing on clear polycarbonate:
When the graphic or advertisement must look correct both during the day (without backlighting) and at night (with LED backlight), UV printing in CMYK–white–CMYK mode ensures proper color saturation.
This works perfectly with a properly calibrated UV printer (e.g., the Canon ARIZONA used in our company) and appropriate LED color temperature.

Printing on clear glass:
For example: commemorative plaques with photos, EU plaques, glass art prints, and backlit graphics — all require a white underprint to ensure accurate color reproduction.

Applications:

• LED-illuminated display cubes

• Glass plaques and glass panels

• UV prints on clear or colored plexiglass

• Double-sided window stickers

• Backlit advertising lightboxes

• Plexiglass or glass trophies with double-sided printing

• Plexi information boards (UV prints on clear or colored plexi)

• Colored rigid panels (but not white), e.g.:

  • brushed silver dibond

  • aluminum

  • brushed stainless steel

• Wood-based boards

Example:

An example of CMYK – WHITE – CMYK UV printing on a 100×200 cm clear solid polycarbonate sheet, installed inside an LED-illuminated display cube.

Thanks to this UV printing technology, the colors are perfectly reproduced when backlit, and remain accurate during the day when the LED lighting is turned off.