In the color light addition method, equal proportions of the three color lights are added and mixed to form white light. Blue and green light are mixed into blue light, blue light and red light are mixed red light, green light and red light are mixed into yellow light and so on. These phenomena are unacceptable to most people, because people's broad practice is the subtractive method - the addition of color bodies, such as drawing color pictures, paint color matching, etc., are all subtractive principles, and for a For an offset printer operator, it is not only necessary to understand the principle of color light addition, but more importantly, how to use the principle of subtractive color to guide actual operations. In the actual printing, according to the original design needs, sometimes need a special color as a foil. In addition, some products printed with four-color original ink are not easy to control because of overprinting problems and ink-water balance. It is not easy to achieve the desired reproduction effect. Sometimes, spot color printing is also required. Especially in packaging and decoration printing, some products pursue individuality. More choices for spot color printing.
Carefully analyze the manuscript or sample draft before deploying ink.
When analyzing a color draft, the color of the color draft and the ink used are mainly analyzed. The basic principle is that the three primary colors of pigments are the basic colors of all inks, and they must remain the same. At the same time, it is necessary to make clear as far as possible whether the color draft is based on network printing or on-site printing. If the network printing is the main method, the ink color should be focused on the same color. If the printing is mainly based on the field, the ink can be mainly focused on the face color. If the two are combined, the background color when the ink is mixed. Both look and look.
When the color draft is analyzed, the color of the used ink should be analyzed. In general, the ink preparation operator or the captain is particularly sensitive to the observation of the color of the ink, and the components thereof can be seen, for example, the yellow ink, to be good at identifying it. Is it with a yellow phase or with a blue phase (or with a green phase), for magenta ink, it is good at identifying whether it has a red phase or a blue phase (or purple phase). For blue ink, it is better to identify it with red The phase is still green (or yellowish). If green ink with a red ink with a red phase and yellow ink with a red phase are used, the resulting green color will be dark because it is actually equivalent to adding a magenta ink to the yellow ink and yellow ink (yellow + blue + product). Red = black), so observing the color of ink is an essential basic skill for offset printing operators.
The basic principles of the deployment of spot color ink
Whether it is a dark or light spot color ink, the basic principles should be followed when deploying. This basic principle is based on the printing color and printing process. The main content includes the following ten points:
(1) Try to use the same type of ink and the same type of auxiliary materials. In addition, do not use three primary colors of inks that can be formulated with two primary color inks. Similarly, if you need a certain color to match, you must use the original color ink, so as not to reduce the brightness of the ink, affect the color and vividness. When deploying dark ink, the main color ink should be placed in the ink tray according to the weight of the ink, and then auxiliary colors and necessary auxiliary materials should be gradually added.
(2) Where the diluting agent is used as the primary color, or the primary color or the dark ink is used as the supplement, the formulated ink is collectively referred to as the light color ink. The method of light-colored ink is slightly different from the dark-colored ink in the method, and the dark ink is gradually added in the light-colored ink. Can not cut dark ink before adding light color ink, because the light color ink poor coloring, if you add dark ink in light-colored ink to adjust the alignment is not easy to adjust the hue, the ink will often make more adjustments.
(3) Prepare a small sample before dispensing the spot color ink. This is to say that the color of the ink to be used is determined based on the initial judgment of the original hue, and then a small amount of ink is weighed out from the various inks using a balance, accurately weighed, placed on the ink adjustment table, and then a small sample is scraped with a spatula. Perform the inspection as it is, and make relevant records and keep it properly.
(4) When color mixing spot color inks are used, the complementary color theory is used to correct the color shift. For example, when the purple flavor of a certain complex ink is heavy, yellow ink may be added to correct it; if the red flavor is heavy, blue ink (such as peacock blue or sky blue ink) may be added to correct; if the black ink of black ink is not enough , can add a small amount of light blue as a pigment, because the blue light is blue with red ink, help to improve the darkness of black ink.
(5) Grasp the hue characteristics of commonly used inks. In the actual operation, we must master the hue characteristics of commonly used inks. For example, in the deployment of light lake green ink, it is appropriate to use sky blue or peacock blue, avoid using dark blue to deploy, because the dark blue ink ribbon red, after joining, the color must be dark and not bright, the same reason, can not use reddish deep Yellow ink, and the use of partial yellowish yellow ink effect is better, and as an example, the deployment of orange ink when possible to use gold and red ink, because the gold red ink hue is red yellow, can increase the degree of ink vivid. In addition, the selection of some inks should be determined according to the screen effects. For example, the inks of the portraits and landscapes selected for printing should be different.
(6) Pay attention to the specific gravity of different inks. The proportion of ink is generally different, inks with similar proportions are easy to mix, and inks with a large difference in specific gravity can cause print defects, for example, green ink formulated with heavy lead-chrome yellow ink and peacock blue ink. For a long time, the small proportion of color inks will go up, and the larger ones will sink, so there is a "floating" flaw. If yellow ink made of organic pigments is used for deployment, rickets will disappear. In addition, due to the fact that the white ink ratio is significant, in addition to the requirements for masking and color matching when adding a small amount, try not to dilute with white ink (if the film is not the same as the live work), in order to prevent poor stacking and color quality problems.
(7) Reasonably choose the diluting agent to master the degree of diluting. When the hue and the amount of ink are used, the diluting agent must be reasonably selected, for example, the thinner used for the printing offset paper and the coated paper. In addition, the degree of diluting is an important technical aspect. If the diluting ratio is small, the surface of the printed product is prone to blooming, the ink layer is dry and the color is not bright; if the ink is diluted too much, only the ink layer thickness can be increased to achieve the printing needs. Hue, it is easy to make the layout low-key areas paste version, so that it can not tell the depths. At the same time, there will be through-printing phenomenon. In addition, for non-light resistant, original inks that are resistant to oxidation and tend to change color are avoided as much as possible for the deployment of light-colored inks, so as not to cause color instability.
(8) Match the spot-color ink scraping paper with the printing paper to avoid the color difference caused by different paper.
(9) When adjusting the spot ink, pay attention to the density of the sample. Generally, when the fresh ink just adjusted is close to the color of the print provided by the customer, the color change will occur after the new ink is dried, so the fresh ink that has just been adjusted cannot be lighter than the printed sample.
(10) Take into account the characteristics of post-press processing. When selecting the ink, consider the post-press processing conditions. If the printed product requires glazing, select the general ink. If you select the ink with good friction, it will not only cost but also affect the glazing effect.
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