Printing spot color features and operations (on)

Editor's Note: Spot ink is 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. Here we come together to understand its characteristics in the actual operation and some issues that should be noted:
First, the characteristics of printing spot color:
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 property. 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 performance 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 is often to use the characteristics of spot color ink in the color dot printing to select and use it. In general, it is generally used in two situations:
1. In order to print on the printed matter, some visible colors of color outside the color space of CMYK four-color printing ink 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 of various processes in the overall printing process, equipment maintenance, operating environment, artificial omissions, and mechanical wear and tear, it is difficult to obtain even and smooth dot colors when printed at 153 or less dots. At this time, we can use the same color. The full version of the color (ie spot color in the field) instead of a small dot for printing, it can 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. If FreeHand names PANIonEI 1F5 PANTONE 1F5CVC or PANIONE 1F5CVV, PageMaker is named PANTONE1F5CV. 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 issue of spot color screening 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 angle 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, blue is 75 degrees), there are spot colors, or there are more than two spot colors, when the color separation screen is output at 45 degrees, so when using shallow network for spot colors, if There may be overprinting with other screening colors. You must open the software color setting or print setting dialog box when the color separation is output to modify the spot color screening angle. (To be continued)