The skills you have to know for book printing
1. The effect of paper on color
The influence of paper on the color of the ink layer is mainly reflected in three aspects.
(1) Paper whiteness: Paper with different whiteness (or with a certain color) has different effects on the color of the printed ink layer. Therefore, in actual production, the paper with the same whiteness should be used as far as possible to reduce the influence of paper whiteness on the printing color.
(2) Absorbency: When the same ink is printed on paper with different absorbency under the same conditions, it will have different printing gloss. Compared with coated paper, the black ink layer will appear dull and dull, and the color ink layer will drift, and the color of cyan ink and magenta ink will be the most obvious.
(3) Gloss and smoothness: The gloss of the printed matter depends on the gloss and smoothness of the paper. The surface of printing paper is a semi-gloss surface, especially coated paper.
2. The effect of surface treatment on color
The surface treatment methods of packaging products mainly include lamination (bright film, matt film), glazing (covering bright oil, matt oil, UV varnish) and so on. After the printed products undergo these surface treatments, there will be varying degrees of hue change and color density change. When covered with glossy film, covered with glossy oil and UV oil, the color density increased; when covered with matt film and covered with matt oil, the color density decreased. The chemical changes mainly come from the various organic solvents contained in the laminating adhesive, UV primer, and UV oil, which will change the color of the printing ink layer.
3. The impact of system differences
The process of making a color card with an ink spreader and an ink spreader is a dry printing process without water, while printing is a wet printing process, with a wetting liquid participating in the printing process, so the ink must be emulsified in water in offset printing. Phenomenon, the emulsified ink will inevitably produce color difference due to changing the distribution state of pigment particles in the ink layer, and the printed product will appear dark and not bright. In addition, the stability of the ink used to prepare the spot color, the thickness of the ink layer, the accuracy of weighing the ink, the difference between the old and new ink supply area of the printing machine, the speed of the printing machine, the amount of water applied during printing, etc. will also have different effects on the generation of color difference. Impact.
4. Printing Control
Whenarrange book printing, the printer uses the printing standard color card to control the thickness of the spot color ink layer, and at the same time assists in measuring the main density value and Bk value of the color with a densitometer to overcome the difference between the dry and wet color density of the ink. In a word, in packaging printing, there are various reasons for the color difference of spot colors. It is necessary to analyze the different reasons in actual production, solve the problem, try to control the deviation to the minimum range, and produce packaging printed products that satisfy customers.
5. Text adjustment
The font, font size and complete reproduction of pictures and texts should be taken into account in the design selection, and the reproduction of picture tone levels should be considered for books with alternate pictures and texts. If it is a picture with very rich layers, the printing pressure and the thickness of the ink layer should be strictly controlled. If the strokes of the designed characters are too thin, there may be broken strokes and missing strokes, and if the strokes of the designed characters are too thick, the characters will be overpowering, and even people will be distracted. The layout is not clean; try to avoid the use of small reverse-white text in the four-color overprinting screen; small text cannot be overprinted with four-color, and replace it with black version or spot color text during plate making.
6 Resolution settings
The resolution should match the paper texture (paper's absorption of ink), generally coated paper uses higher resolution (such as 350-400dpi), offset paper uses lower resolution (such as 300dpi), and the texture is lighter and lighter in particular, high-resolution paper cannot be used. Otherwise, if the high-resolution is printed on light-weight paper with strong ink absorption, the dots will increase significantly, resulting in unclear layers, which is counterproductive.
7. Keep the tone of the picture consistent
Photos or illustrations in the same book should be consistent in tone or style, especially when three or four pictures are put together (as shown in Figure 1, the main body, hue, saturation, hue, level and clarity are initially inconsistent, and it is necessary to Adjustment and coordination), due to differences in the style of the originals or the quality of the pictures, it is necessary to re-plate and adjust, and adjust the patterns or photos that are inconsistent with the pattern tone of the whole book. The tone of the pictures in the monochromatic book should be relatively consistent, otherwise, even if the text ink color is guaranteed to be consistent, the reader will still feel that the ink color is dark and light (as shown in Figure 2), which can be corrected by adjusting the image tone through plate making.
8 sets of book printing ink color determination
If the book is a series of books, the contents of each sub-volume should be read carefully, and the sub-volumes with different contents must be kept in the same style. For example, some of the individual books are pure black and white text, and some of them are color pictures and text and some single volumes are mostly line drafts with monochrome patterns (as shown in Figure 3). At this time, firstly find the text ink color of the single book with many color pictures, and use the text ink color as the benchmark to determine the text ink color of other monochrome books in the set, and take into account the uniform thickness and unevenness of the lines in the book with many line draft patterns. False flowers, continuous lines.
Books are the carrier of human knowledge, the crystallization of human wisdom, and the ladder of human progress. As an industry that produces printed books, everything we do is to continuously improve the spiritual sensibility of the people through books, an important carrier for enhancing the quality of the people. High-quality books printing is not only one of the requirements for high-quality development of the book printing industry, but also to better meet the people's growing needs for a better life. It is hoped that this article can provide some inspiration and reference for printing companies in the process of high-quality printing, and hope that more and more high-quality books will be presented in our lives.