How to test the printing process

The most common method for checking the quality of printing during the printing operation when looking at the sample. Whether it is monochrome printing or color printing, operators must often use their eyes to repeatedly compare the prints and proofs to find out the difference between prints and proofs, correct them in time, and ensure the quality of printed products. The following questions are worth our attention when printing samples:

One: The strength of light directly affects the judgment of the color of printing samples

The strength of light not only affects the color of light, but also changes the appearance of color.

We usually observe a light-receiving cylinder. The light-on side is the tone, and the back-light surface is the dark tone. The combination of light and dark is the midtone.

The same object, under the standard light source, is a positive color. If the light gradually becomes stronger, its hue will also change to a bright hue, and the light will be enhanced to a certain degree, and any color may turn white. Black porcelain also has a white point of reflection because of the concentration of light at the point of reflection and its strong reflection. In the same way, the light gradually decreases, and the various colors change to a hue with low lightness, and the light weakens to a certain degree, and any color will turn black, because the object does not reflect any light or black. Table 1 shows the effect of light intensity on color.

The sample stand in the printing shop must meet the requirements. Generally, the illuminance must reach about 100LX in order to correctly identify the color.

II: There is a difference between seeing light and seeing under sunlight

In production practice, most of them work under the illumination of a power source, and each light source has a certain color. This brings certain difficulties to the correct judgment of the original or product color. Under the shade of color, the color change is generally the same color becomes lighter and the complementary color becomes darker. For example, the red color is lower, the red is lighter, the yellow color is orange, and the green color is changed. Dark, dark green, white red.

Under the green light, the green lighter, the green lighter, the yellowish greenish yellow, the reddish black, and the white green.

Under the yellow light, the yellow lightens, the magenta turns red, the green turns green, the blue turns black, and the white turns yellow.

Under the blue light, the blue lightens, the green lightens, the green darkens, the yellow turns black, and the white turns blue.

In the printing shop, generally choose a fluorescent lamp with a higher color temperature (3500~4100K) and better color rendering coefficient as a sample light source, but be aware that the fluorescent lamp is slightly blue-purple.

Three: First look at the proofs and then look at the printed products and first look at the printed products and then look at the proofs, the results will be slightly different

It doesn't feel the same when you look at a color twice. This phenomenon is called sequential color contrast reaction. See Table 2 for the changes.

Why do you have successive color contrast reactions? This is because the first look makes the color of the colored nerve fibers excited, immediately look at other colors, other color nerves quickly excited to cause a sense of color, while the color of the first look at the color of the nerve after the suppression of excitement, and then excited Slower, causing a negative hue response. This reaction adds a new color hue to create a new color, so change the look after the color. Moreover, the hue of the change is still regular, and it is the change in the complementary color of the first look.

Understand the above three issues and understand their changing patterns, we should pay attention to the actual look, so as to ensure the stability and improvement of the quality of printed products.

The color of the eyes that first looks at and the color of the eyes

Red yellow green blue purple white

Red earth red green yellow green blue blue green Tsui

Yellow Purple Red Gray Yellow Green Blue Fresh Purple Purple Purple

Green, red, orange, gray, purple, purple, red, magenta

Blue orange golden yellow green gray blue red purple light orange

Purple Orange Lemon Yellow Yellow Green Blue Blue Grey Purple Green Yellow

Reprinted from: China Packaging Trade Network