Printing Color Knowledge

What is CMYK?

CMYK refers to the four-color printing mode, which is a color mode used in color printing. It uses the three primary colors of pigments to mix colors, and adds black ink to form a total of four colors. The mixture and superposition of colors form so-called "full-color printing".

Each CMYK ink can use a value from 0 to 100%. The percentage of printing ink color specified for lighter colors is lower, while the percentage specified for darker colors is higher. For example, bright red may contain 2% cyan, 93% magenta, 90% yellow, and 0% black.

What is Spot Color?

Pantone colors are also called spot colors, which means that when printing, this color is not synthesized by printing the four colors of CMYK, but a specific ink is used to print the color.

For example, the color C-30, M-20, Y-100, normal four-color printing is to use three printing plates to print the three colors of C, M, and Y on the same paper to form the color. If this color is printed in spot color, the ink according to C, M, and Y needs to be mixed in a ratio of 3:2:10 in advance, and then a printing plate is used to print the color on the paper.

The advantage of spot color printing: it can avoid color deviation caused by multiple printing to the greatest extent.

Common Pantone color cards

Common Pantone color cards are C card and U card, which are PANTONE+Solid Coated and PANTONE+SolidUncoated, respectively.

PANTONE color shade number ending with C means the material of the color card is coated paper, and the color is glossy. PANTONE color shade number ending with U means the material of the color card is offset paper, and the color is matte. The two color cards are 1114 colors of the same color, but the colors are different on different materials.

Characteristics of spot color

Often a single color is a company's brand image, and if each batch is different, customers will think it is a pirated package.

Therefore, one of the common reasons for using spot colors in packaging printing is to ensure that the colors printed in each batch are the same. In addition, spot colors are mixed in specific proportions, and the colors will be more vivid and beautiful than those produced by four-color printing.

Packaging printing usually uses four primary colors, sometimes with an additional spot color. In cases where there are too many colors, there will be combinations of 4+1 or 4+2.

Four main characteristics of spot color:

1. Accuracy: Each spot color has its own fixed hue, so it can guarantee the accuracy of the color in printing, thereby solving the problem of color difference to a large extent.

2. Solidity: Spot colors are generally defined by solid colors, no matter how light the color is. Of course, spot colors can also be screened to present any shade of spot color.

3. Opacity: Spot color ink is a covering ink. It is opaque and can be overprinted.

4. Wide color gamut: The color gamut of spot color libraries is very wide, exceeding the color gamut of RGB, not to mention CMYK. Therefore, there are a large number of colors that cannot be presented with CMYK four-color printing inks.

When to use spot color printing

1. Single-color or two-color books: Only 1-2 colors are used, and single or two-color printing presses can be used to reduce printing costs.

2. For better effect of large-area color blocks: Four-color printing uses dot superposition. If spot color printing is used for large-area color blocks, the color can be more standard and the solid bottom effect is better.

3. Very high color requirements: For example, corporate standard colors, designers will specify Pantone spot color values. The color of printed products in different batches of four-color ink printing will inevitably vary, while Pantone color values are universally used in the world, and Pantone ink manufacturers are professionally prepared to minimize color deviations.

4. Special spot color inks are required: Gold, silver, fluorescent ink, etc. are all CMYK four-color inks that cannot be prepared, so spot color printing is required.

The difference between spot color and four-color printing

Spot color printing: The color lightness is lower and the saturation is higher; the spot color block with uniform ink color is commonly used for solid color printing. The ink volume should be appropriately increased. When the ink layer thickness on the plate is large, the sensitivity of the change in ink layer thickness to the color change will be reduced, so it is easier to obtain a uniform and thick ink color printing effect.

Four-color printing: The color blocks printed by the process overprinting are prone to color intensity changes due to changes in ink layer thickness and printing process conditions. Changes in the degree of dot expansion, thereby leading to color changes. Therefore, it is difficult to obtain a uniform ink color effect for the color blocks overprinted by the four-color printing process.