Why spot color printing is more and more loved by designers

First, spot colors and their characteristics

Spot color ink refers to a pre-mixed specific color ink, such as fluorescent yellow, pearl blue, metal gold silver ink, etc., it does not rely on CMYK four colors mixed, trapping means accurate color. It has the following four characteristics:

1. Accuracy. Each color registration has its own fixed hue, so it can guarantee the accuracy of the color in printing, thus solving the problem of color transfer accuracy to a great extent;
2. Field performance. Spot colors generally define colors in solid colors, regardless of how light they are. Of course, Tint can also be given to display any shade of spot color;
3. Opaqueness. Spot color ink is a covering ink, it is opaque and can be covered in the field;
4. Wide color gamut. The color gamut in the color bank is very wide, exceeding the RGB color gamut, not to mention the CMYK color space, so a large part of the color is not present with the CMYK four-color printing ink.

Second, the reason for choosing to use color in color dot printing

In color dot printing, the characteristics of spot inks are often used to select and use them. In general, it is generally used in two situations:

1. In order to print on the printed matter, the color of visible light outside the color gamut of some CMYK four-color printing inks can be printed. The color gamut of CMYK four-color printing ink is obviously insufficient compared with the visible color gamut, while the color gamut of spot color ink is wider than that of CMYK four-color printing ink, so it can express many colors other than CMYK four-color ink;

2. To make up for the lack of printing technology. Due to the errors in various processes in the overall printing process, equipment maintenance, work environment, human error, and mechanical wear and tear, it is difficult to obtain even and smooth dot colors when printed at 153 or less outlets. At this time, we can use the same colors. The full version of the color (ie spot color in the field) instead of a small dot to do printing, it will be easier to get a flat large area color. In addition, sometimes in order to be able to clearly show the fine picture, such as the fine strokes of mixed color graphics or anti-white lines, etc., also often use spot color processing in order to fine lines can be expressed enough to be real and delicate.

Third, the use of spot colors before printing should pay attention to some issues

1. The unity of spot color names. In different software, the names may be different for the exact same two colors. For example, FreeHand names PANIonEI 1F5 PANTONE 1F5CVC or PANIONE 1F5CVV, while PageMaker names it PANTONE 1F5CV. In this way, when FreeHand graphic objects are placed in PageMaker, the same color will have three names. When the color separation is output, three printing plates will be generated, causing output errors. Therefore, if the data file needs to be used in more than two kinds of software, before the integrated color separation output, it must be noted that the use name of the same spot color must be unified. The more common method is based on the name of the color in the distribution software, and the name of the same spot color is renamed as a unified name in the palette of various software.

2. Spot color screening angle. In general, spot colors are printed in the field, and they are rarely processed at the outlets. Therefore, the point of spot color screening is rarely mentioned. However, when using a lighter mesh color, there will be problems with the design and modification of the spot color screen dot. If there is an overprint area between the spot colors of the outlets and the colors printed by other outlets, the spot color screening problem must be considered. At this time, if the angle formed by the spot color screen's screen angle and other color screen angles is less than 30 degrees, collision or moiré will occur; if the angles overlap each other, ink overprint problems will result, which will result in The color of the print is seriously distorted. In addition, the screen angle of spot colors is generally preset to 45 degrees in software (45 degrees are considered to be the most comfortable angles for human eyes, so that the dots can be arranged in the same direction as the horizontal and vertical lines. The ability of the human eye to detect dots, if it is a two-tone image or data file, it is printed in four colors and black (usually in four-color screen printing, the black dot is placed at 45 degrees, yellow is 0 degrees, Magenta is 15 degrees, green is 75 degrees), there are spot colors, or there are more than two spot colors, it will output at 45 degrees in color screening, so when using shallow mesh for spot colors, if It is possible to overprint with other screening colors. You must open the dialog box for software color settings or print settings during color separation output to modify the spot color screening angle.

3 spot color to print four-color conversion. Many designers often use the colors in the spot color library to define colors and perform coloring when they do graphic design. In color separation, they are converted into CMYK printing four colors. At this time, pay attention to three points: First, the spot color gamut is larger than the printing four-color gamut. In the conversion process, some spot colors cannot be faithfully completed, and some color information will be lost; second, the output must be selected." Spot color conversion becomes a four-color "choice, otherwise it will result in an output error; Third, do not think that the CMYK color numerical ratio displayed next to the spot color number allows you to reproduce the spot color with the same four-color ink of the same CMYK component." If you can use it, you will not need to use spot colors. In fact, if you do so, the resulting colors will have a large difference in hue.

4. Spot color trapping. Because the spot color is different from the four-color printing (printing the four-color ink to generate inter-color printing on each other, that is, the ink has transparency), the inter-color is not usually generated by superposition of two spot colors. Intuitively, that will be Get a very dirty color effect (of course there are exceptions, such as the intention in the design of the use of spot color overprint processing to produce the required, superimposed blend of the third color, this third color is full, thick and real, such as: spot color yellow On-press embossed spot color red, two colors superimposed to produce a steady dark red, often used as a book cover, etc.), so the definition of spot colors, generally do not use overprint (Overprint) but to use empty ( Keepaway). In this way, when spot colors are used, as long as there are other colors next to spot color patterns, appropriate trapping should be considered to prevent the problem of dew-white spots. (The method for trapping spot colors and related technical issues are more complex. This is not repeated).

5. Spot color matching system. When choosing a computer color matching system, first of all, it should be clear which are the spot color systems and which are the CMYK four-color printing systems, so as to know whether the color you choose to use in the system will have color conversion and whether it will Color distortion occurs. For example, color matching systems commonly used in graphic software include PANTONE, TRUMATCH, FOCOLTONE, TOYO ColorFinder, ANPA-COLOR, RIC Color Guide, etc., among which TRUMATCH, FOCOL TONE, and ANPA COLORR are based on a four-color printing system. Others All belong to the system of spot colors (the PANTONE system covers a wide range of colors, both process and spot).

That is to say, in spot color matching systems such as PANTONE spot colors, TOYO Color Finder, and RIC Color Guide, many of these colors have exceeded the printing four-color color gamut and cannot be reproduced with four-color inks. The system provides CMYK combinations. Values ​​are only approximations. So if you have selected the colors in the spot color matching system and printed them in four-color printing, or referenced the corresponding CMYK combination values ​​that the spot colors displayed in the system, and used these values ​​to replace the printing four colors. The original spot color, the result will definitely lead to color distortion; Second, it should be understood that the spot color matching system when doing color separation processing, unless specifically set to convert the spot color to CMYK four colors, otherwise, each used Spot colors are automatically divided into a single color version. In the same way, after the colors in the four-color color matching system are used for coloring, the color-to-color output will automatically follow the color's own CMYK ratio to four plates without producing more. The color version.

Second, note that in the context of a dot-matrix diagram, the selected color (for example, a spot color) is automatically converted to the same color mode as the data file to which the color is applied (for example, CMYK four-color mode) after it is used on the canvas. . So in the dot matrix drawing software, for the spot color, it must be added or specified intentionally. (For example, to add and define a spot color in Photoshop, there are two situations: if you apply a spot color as a tone to the entire image , you need to convert the image to a two-tone mode and apply a spot color to one of the two-tone plates; if you use a spot color for a specific area of ​​the image, you must create a spot color channel; and in a vector drawing environment, When a spot color is selected or defined, the color will always exist as a spot color attribute unless the spot color attribute is specifically changed or converted to a process color (eg, a spot color added and defined in Yiiustrator, even if it is referenced In other Illustrator data files, data files that will use this spot color are opened with other vector software, and the color attributes of this spot color are not changed.)

6. The cost of spot color printing. General spot color printing is generally used for printing below three colors. If four or more colors are required for printing, four-color printing of CMYK is suitable. Because CMYK four-color printing is basically based on dot overprinting, and using spot colors is basically printed in the field. Although the spot color is usually only used locally in the image, it is customarily used twice the price of ordinary printing ink. To estimate; In addition, if the same layout has four printing colors, it is equal to one more color for printing, if the printing press has no extra printing units (such as less than four color printing machines or four color printing machines. ), it will take twice as much time to print, and the cost will be higher.

In short, special care should be taken in the use of spot colors, otherwise it will not only cause color distortion, spoil your creativity and design, but also increase economic expenditure and unnecessary time waste.

Reprinted from: Morning Printing