Ink preparation method quickly grasp

Printing is an industry centered on color theory. In addition to the use of four-color inks in current prints, spot-color inks are also used at higher frequencies, especially in screen printing and gravure printing. Sometimes spot color inks can be printed by direct purchase, sometimes they need to be prepared with primary color inks for cost or special ink color requirements. In general, there are mainly two methods of blending inks. One is based on the basic data obtained by the ratio of instruments (such as densitometers) or chromatograms, and the other is that the operators of the machines directly rely on experience to perform the deployment. The latter method is currently more commonly used, but the experience requirements for printing operators are relatively high. How to grasp this technology quickly is the expectation of those who are involved in the printing industry.

Most of the vocational schools in the country that have set up printing professions have ink-transfer training courses to cultivate students' sense of color and master the techniques of ink deployment.

As an internship instructor for a vocational college, the author takes the first-line teaching experience of the ink-transfer training course and believes that the key to grasping the ink deployment is to grasp the three aspects of “fine”, “bo”, and “walk”. "Qing" and "Bo" are comprehensive professional theoretical knowledge of ink transfer. "Running" is to apply theoretical knowledge to practice through some practical operations. Below is a brief explanation.

1 "Precision": Highlighting the Theoretical Essence in Teaching Transferring Ink Training

Students must have studied the course of "Printing Colorology" before attending the training courses for ink transfer, which has a certain professional theoretical basis. Therefore, in the teaching of ink-transfer training, teachers should grasp key theories that are closely related to practical application and should be thoroughly explained.

1) The color theory of ink color mixing: subtractive color mixing

Y+M=R, Y+C=G, M+C=B, Y+M+C=BK

C, M, and Y are the three primary colors of the colorant and cannot be obtained by mixing other colorants. The inter-color refers to the color obtained by mixing two primary colors, and the typical inter-color is R, G, and B, and the color obtained by mixing two or more Y, M, and C colorants in different amounts. Complex color refers to the color of the three primary colors mixed. Complementary color means that if two colors are mixed, they are complementary colors if they are black. The most typical three pairs of complementary colors are Y-B, M-G, and C-R.

The spot color is usually used in packaging and printing. A spot color means that a certain color is not a four-color overprint, but a special printing plate must be prepared first, and colors should be specially prepared and printed out at one time. Its characteristics are: usually used in the occasion of high printing color requirements; through the use of spot color ink to expand the scope of color reproduction; some colors are not available through the four-color printing; the use of spot colors can also solve the problem of color overprint is not allowed. The deployment of spot color inks is a key and difficult point in the teaching of ink-transfer training. Practical training instructors must focus on explaining and linking spot-color inks to students.

Professional ink deployment method: see the color of the sample to judge, through the deployment of experience, you can also rely on the proportion of chromatography to deploy. However, the chromatogram indicates that the number of colors is limited, and the color in the chromatogram is affected by paper, ink and printing conditions. Over time, the physical and chemical properties of the ink paper will change, affecting the use value of the color.

2 "Bao": Refers to and quotes related theoretical knowledge

Since color science is the core of printing, it is possible to introduce the part of the theoretical course related to color performance in the teaching of ink-transfer training. Such as "printing materials" course of paper performance and color performance, ink adjustability of the impact of the agent, "printing process" by the density meter to calculate the ink color elements, color sequence arrangement of the ink And so on, let the ink-transfer training not only stay in the simple hands-on operation, truly connect theory with practice, apply what they learn.

Or we can use the experience in actual operation, the color rendering effect of different printability papers on the ink, the effect of various ink additives on the performance of the ink, the characteristics of the ink itself, the influence of the work environment in the workshop, and the arrangement of the printing color sequence. The relationship of the final color effects, etc. Of course, these take some time to accumulate.

1) Grasp the factors related to color performance

1 paper factor

Paper has a close relationship with ink coloration, such as the smoothness and whiteness of paper. In practical training, the teacher can design the students to use the same color ink, play on the scratch paper with different smoothness and whiteness, and observe the difference in color.

2 process factors (such as the use of fountain solution)

During the printing process, changes in process factors will affect the performance of the ink, such as variations in fountain solution concentration and pH.

3 Addition of ink adjustability adjuster

The ink compatibility adjuster itself is not colorless and transparent, and adding it to the ink affects the hue of the ink. Therefore, it should not be added in the multi-color printing, and it is generally added to the last color when it is necessary to consider the influence of the ink conditioner on the viscosity of the ink.

4 Influence of Light Source

Daylight is the best and most suitable light source for observing colors. However, there is a flaw in daylight lighting, which is affected by changes in area, season, weather, and time. According to the international standard ISO 3664, the observation of color samples (transparent and non-transparent) should use the D50 standard light source (D: light source to simulate sunlight, 50: color temperature value. It is 5003°K). The light source during the practice is consistent with the light source of the printing environment, which helps to improve the accuracy of color sensitivity.

5 color sequence arrangement

The basic color sequence of four-color printing is BK→C→M→Y. The color sequence of printing is different, and there will be a certain gap in the color effect of the final printing product.

2) Precautions

1 Use standard light sources when observing print colors.

2 The scraping sheet used in the adjustment of the ink is the same as the substrate.

3 In practical training, teachers should actively guide students to avoid waste and develop good production habits.

4 dark ink deployment: only with the original color ink deployment, does not add any thinner, collectively referred to as dark ink deployment. Preparation method is to continuously add auxiliary color ink in the primary color ink.

5 light-colored ink deployment: where the ink is prepared by adding dilute agent, collectively referred to as light-colored ink. The deployment method must not be added to the original ink diluting agents to deploy. Because the primary color ink has a strong color development ability in the diluting agent, and the coloring ability of each primary color ink is different, the general rule is black> magenta> cyan> yellow, so it is easy to cause inaccurate hue and waste of ink. It is generally adopted in the diluting agent to gradually add the primary color ink to be blended, and it is firstly adjusted to a small amount. After the color meets the requirements, the amount of ink consumed in the deployment printing is further increased. In short: mainly diluting agent, add primary color ink, dark color to light color Riga.