1 The definition of light coated paper
Lightweight paper is a coated paper with a lower specified amount [encyclopedia], also known as low-weight coated paper, whose English name is LWC paper (ie, Light Weight Coated Paper). It is a thin layer of paint on the front and back sides of the base paper. The coating is more uniform, with excellent rheology and water retention, and then super-calendered to improve its physical properties and printing [ Encyclopedia] fitness. The base paper has a low basis weight of about 30 to 60 g/m2, and the coating amount is usually 5 to 10 g/m2 per side. Therefore, the weight of the light coating paper is 40 to 80 g/m2, which is the sum of the base paper's basis weight and both sides' coating amount. . It is widely used in the color printing of general public products such as books, magazines, catalogues, advertisements, and trademarks. The printing effect is comparable to that of coated copperplate paper to a certain extent. However, the material cost is relatively low, and well-known domestic paper manufacturers can also Mass production and put into the market, some of the characteristics of light coated paper gradually understood and mastered by people.
2 Lightweight paper features
1) The printing quality is better. From the paper's performance, light-coated paper is between the coated paper and offset paper, and has good opacity and smoothness, as well as paper gloss and print gloss, printing on low-quantitative paper color products On the other hand, the printing effect is comparable to that of coated paper, which is different from the main characteristics of offset paper. For general color printing products, such as books and magazines, color pages of newspapers and magazines, color papers with a specific weight as low as 50 to 70 g/m2 can be used, and the effect of 70 to 90 g/m2 of coated paper can be achieved. Readers and users can also Accepted, deeply loved by print and publishers.
2) Lower production costs. As the light-coated paper is a low-precision paper, the production is mixed with cheaper mechanical pulp and filler, so the investment in raw material costs is not high, and the selling price is only 5 to 10% more expensive than the ordinary offset printing paper. Similar coated paper is about 10% cheaper.
3) The durability is poor and the adaptation range is narrow. In the manufacture of light-coated paper, the base paper contains a large amount of mechanical wood pulp, and the remaining lignin and other compounds in the mechanical wood pulp discolor the paper sheet, cause brittleness and damage, and are therefore more suitable for printing products that do not require long-term preservation and use. There are many applications such as books, newspapers and magazines of cultural fast food, and commercial promotion advertisements. The reference books and dictionaries are not suitable for printing on light coated paper.
4) Lightweight paper is not very suitable for printing high quality products. Affected by too much filler and excessively thin coating layer, the easy-to-paper-off powder and surface glossiness during printing are relatively poor (as opposed to coated paper), and it is difficult to print any high-grade products. At the same time, the paper is thinner and more The accuracy of color overprinting is generally around ±0.05-0.1mm, and the thin line and text combination of multi-colored inlays will inevitably be biased, appearing ghosting and affecting product quality.
5) Lightweight paper cannot be used as writing paper. Due to the limitation of the paper structure, when writing with ordinary ink, the handwriting is difficult to dry in time and the adhesion performance is poor, which is one of its defects.
3 Prepress plate synthesis consideration is the key
As the saying goes, “seven-point edition and three-point printing†mean that the quality of product quality is generally determined by platemaking. It should be based on the requirements of product quality, production characteristics of printing machines, printing suitability of light-coated paper, and application of production processes. Considering comprehensively, we are trying to print a high-level product, so the pre-press plate-making is the key.
1) Scan calibration. In the highlights of the printed image, generally in the highlight area of ​​1 ~ 2% is almost impossible to print (or dot network is full of virtual), which means that the high light part of the print is basically formed by the color of the paper. If the whiteness of the paper is different, the brightness and saturation of the color at the main light of the screen will be affected, thereby affecting the color contrast of the screen. The surface of the light-coated paper has a certain degree of smoothness, whiteness, and light reflection capability. Therefore, for light-coated paper, the black scale calibration is roughly C=85-955%, M=Y=80-90%, K=75- 80%. If there is no white field on the image, you can use the paper color as the reference point for adjusting the white field. Adjust the color dots of CMYK to be less than 3% or less. When there is an output CTP, the calibration value can be appropriately expanded and broadened.
2) Adjust image contrast, sharpness, and dot-to-dot ratio. The stronger the paper absorbency is, the larger the dot gain value is. Specifically, the absorbency of light-coated paper is greater than that of coated paper and that of offset paper. In the process of platemaking, printability compensation must be applied to the effect of dot gain. Generally, the high-profile and dark-tone dot gains of light-coated paper and printing are 10 to 15%, and the midtone dot gain values ​​are relatively large, as much as 15 to 25%. Therefore, it is necessary to appropriately sharpen the image and Adjusting the tone contrast makes the image clearer. This must be done at the expense of the middle tone level of the image, so that the print has good color, good saturation, and bright colors, which can reflect certain levels and contrasts. The contrast between light and dark increases the contrast, brightens bright areas, darkens dark areas to achieve sharpening, enhances the viewing of pictures, and facilitates print reproduction. But excessively sharp contrast and sharpening will make the image too distorted, blunt, and unnatural.
1 The printability of light coated paper lies between the coated paper and offset paper, and the number of hanging screens is set to be about 133 to 175 lines when the lithographic printing machine is used; when the light is coated with high quality, the number of hanging lines can be as high as 200 Line; rotary printing should be moderately reduced to 133 to 150 lines. Products printed with light-coated paper are generally not very high-grade and have high quality requirements. When printed on excessively high-quality screens, they are liable to drop powder and stack ink. However, the expected results are not achieved. At the same time, the printing plate's printing rate is very low. Cost and quality control are not worth the candle.
2 Set flat screen requirements. The large flat screen set on the light coated paper should be between 5 and 65%. It is not easy to over-design dark shades in CMYK color plates because the surface of the thin paper is relatively small and its ink volume is thin, and the blots can easily penetrate the paper surface; at the same time, more than 65% of multi-color overprints of the dots exceed 65%. Caused too many outlets in the area after printing and it is difficult to dry in time.
3 In order to maintain the color brightness and vividness of image printing and reduction, moderate adjustments are made to the dark and dark versions of the blue and black editions. Under the premise of satisfying image tonality, the necessary proportions of ingredients are reduced. Reducing the value of 5 to 10%, the same can also be moderate to the dark tone and dark yellow, red version increased by about 8 to 15%.
3) The total amount of ink is set. Due to the thinness of light-coated paper and the limited production speed of the printing press, it is determined that the total amount of ink in the image cannot be too high. These must be adjusted in place prior to pre-press production. Adjust the parameters accordingly by comparing the actual production. : The total ink volume of light coated paper is generally controlled at 270 to 300%, of which 280 to 300% is printed on lithographic machines, and 260 to 290% is used for wheel transfer. The thinner the paper is, the smaller the total ink volume is, and the ink layer is difficult to remove. Drying can also result in dirty accidents and print quality accidents. The setting of this value is determined by the production process of each unit and the actual printing situation, depending on the dot gain rate at the time of printing. If the dot enlargement rate is too large (when the paper quality is ≥25%, such as some domestic B grade light coated paper), the value must be reduced; otherwise, the dark tone may be easily crushed; If the dot enlargement is basically normal (such as imported light-coated paper ≤ 15%), the value can be appropriately increased to ensure that the dark-sounding part is full-colored, showing a dark tone regional level, and facilitating the necessary reproduction of the entire tone.
4) Establish the necessary color management system, do a good job of recording data, be good at comparison testing, use multiple data analysis, and formulate a suitable light-coated paper print output characteristic curve so that it can be invoked when output.
Lightweight paper is a coated paper with a lower specified amount [encyclopedia], also known as low-weight coated paper, whose English name is LWC paper (ie, Light Weight Coated Paper). It is a thin layer of paint on the front and back sides of the base paper. The coating is more uniform, with excellent rheology and water retention, and then super-calendered to improve its physical properties and printing [ Encyclopedia] fitness. The base paper has a low basis weight of about 30 to 60 g/m2, and the coating amount is usually 5 to 10 g/m2 per side. Therefore, the weight of the light coating paper is 40 to 80 g/m2, which is the sum of the base paper's basis weight and both sides' coating amount. . It is widely used in the color printing of general public products such as books, magazines, catalogues, advertisements, and trademarks. The printing effect is comparable to that of coated copperplate paper to a certain extent. However, the material cost is relatively low, and well-known domestic paper manufacturers can also Mass production and put into the market, some of the characteristics of light coated paper gradually understood and mastered by people.
2 Lightweight paper features
1) The printing quality is better. From the paper's performance, light-coated paper is between the coated paper and offset paper, and has good opacity and smoothness, as well as paper gloss and print gloss, printing on low-quantitative paper color products On the other hand, the printing effect is comparable to that of coated paper, which is different from the main characteristics of offset paper. For general color printing products, such as books and magazines, color pages of newspapers and magazines, color papers with a specific weight as low as 50 to 70 g/m2 can be used, and the effect of 70 to 90 g/m2 of coated paper can be achieved. Readers and users can also Accepted, deeply loved by print and publishers.
2) Lower production costs. As the light-coated paper is a low-precision paper, the production is mixed with cheaper mechanical pulp and filler, so the investment in raw material costs is not high, and the selling price is only 5 to 10% more expensive than the ordinary offset printing paper. Similar coated paper is about 10% cheaper.
3) The durability is poor and the adaptation range is narrow. In the manufacture of light-coated paper, the base paper contains a large amount of mechanical wood pulp, and the remaining lignin and other compounds in the mechanical wood pulp discolor the paper sheet, cause brittleness and damage, and are therefore more suitable for printing products that do not require long-term preservation and use. There are many applications such as books, newspapers and magazines of cultural fast food, and commercial promotion advertisements. The reference books and dictionaries are not suitable for printing on light coated paper.
4) Lightweight paper is not very suitable for printing high quality products. Affected by too much filler and excessively thin coating layer, the easy-to-paper-off powder and surface glossiness during printing are relatively poor (as opposed to coated paper), and it is difficult to print any high-grade products. At the same time, the paper is thinner and more The accuracy of color overprinting is generally around ±0.05-0.1mm, and the thin line and text combination of multi-colored inlays will inevitably be biased, appearing ghosting and affecting product quality.
5) Lightweight paper cannot be used as writing paper. Due to the limitation of the paper structure, when writing with ordinary ink, the handwriting is difficult to dry in time and the adhesion performance is poor, which is one of its defects.
3 Prepress plate synthesis consideration is the key
As the saying goes, “seven-point edition and three-point printing†mean that the quality of product quality is generally determined by platemaking. It should be based on the requirements of product quality, production characteristics of printing machines, printing suitability of light-coated paper, and application of production processes. Considering comprehensively, we are trying to print a high-level product, so the pre-press plate-making is the key.
1) Scan calibration. In the highlights of the printed image, generally in the highlight area of ​​1 ~ 2% is almost impossible to print (or dot network is full of virtual), which means that the high light part of the print is basically formed by the color of the paper. If the whiteness of the paper is different, the brightness and saturation of the color at the main light of the screen will be affected, thereby affecting the color contrast of the screen. The surface of the light-coated paper has a certain degree of smoothness, whiteness, and light reflection capability. Therefore, for light-coated paper, the black scale calibration is roughly C=85-955%, M=Y=80-90%, K=75- 80%. If there is no white field on the image, you can use the paper color as the reference point for adjusting the white field. Adjust the color dots of CMYK to be less than 3% or less. When there is an output CTP, the calibration value can be appropriately expanded and broadened.
2) Adjust image contrast, sharpness, and dot-to-dot ratio. The stronger the paper absorbency is, the larger the dot gain value is. Specifically, the absorbency of light-coated paper is greater than that of coated paper and that of offset paper. In the process of platemaking, printability compensation must be applied to the effect of dot gain. Generally, the high-profile and dark-tone dot gains of light-coated paper and printing are 10 to 15%, and the midtone dot gain values ​​are relatively large, as much as 15 to 25%. Therefore, it is necessary to appropriately sharpen the image and Adjusting the tone contrast makes the image clearer. This must be done at the expense of the middle tone level of the image, so that the print has good color, good saturation, and bright colors, which can reflect certain levels and contrasts. The contrast between light and dark increases the contrast, brightens bright areas, darkens dark areas to achieve sharpening, enhances the viewing of pictures, and facilitates print reproduction. But excessively sharp contrast and sharpening will make the image too distorted, blunt, and unnatural.
1 The printability of light coated paper lies between the coated paper and offset paper, and the number of hanging screens is set to be about 133 to 175 lines when the lithographic printing machine is used; when the light is coated with high quality, the number of hanging lines can be as high as 200 Line; rotary printing should be moderately reduced to 133 to 150 lines. Products printed with light-coated paper are generally not very high-grade and have high quality requirements. When printed on excessively high-quality screens, they are liable to drop powder and stack ink. However, the expected results are not achieved. At the same time, the printing plate's printing rate is very low. Cost and quality control are not worth the candle.
2 Set flat screen requirements. The large flat screen set on the light coated paper should be between 5 and 65%. It is not easy to over-design dark shades in CMYK color plates because the surface of the thin paper is relatively small and its ink volume is thin, and the blots can easily penetrate the paper surface; at the same time, more than 65% of multi-color overprints of the dots exceed 65%. Caused too many outlets in the area after printing and it is difficult to dry in time.
3 In order to maintain the color brightness and vividness of image printing and reduction, moderate adjustments are made to the dark and dark versions of the blue and black editions. Under the premise of satisfying image tonality, the necessary proportions of ingredients are reduced. Reducing the value of 5 to 10%, the same can also be moderate to the dark tone and dark yellow, red version increased by about 8 to 15%.
3) The total amount of ink is set. Due to the thinness of light-coated paper and the limited production speed of the printing press, it is determined that the total amount of ink in the image cannot be too high. These must be adjusted in place prior to pre-press production. Adjust the parameters accordingly by comparing the actual production. : The total ink volume of light coated paper is generally controlled at 270 to 300%, of which 280 to 300% is printed on lithographic machines, and 260 to 290% is used for wheel transfer. The thinner the paper is, the smaller the total ink volume is, and the ink layer is difficult to remove. Drying can also result in dirty accidents and print quality accidents. The setting of this value is determined by the production process of each unit and the actual printing situation, depending on the dot gain rate at the time of printing. If the dot enlargement rate is too large (when the paper quality is ≥25%, such as some domestic B grade light coated paper), the value must be reduced; otherwise, the dark tone may be easily crushed; If the dot enlargement is basically normal (such as imported light-coated paper ≤ 15%), the value can be appropriately increased to ensure that the dark-sounding part is full-colored, showing a dark tone regional level, and facilitating the necessary reproduction of the entire tone.
4) Establish the necessary color management system, do a good job of recording data, be good at comparison testing, use multiple data analysis, and formulate a suitable light-coated paper print output characteristic curve so that it can be invoked when output.
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192 Needles Eye Roller, eye dermaroller, eye micro roller, eye derma roller,eye micro needles roller,eye micro derma roller, eye derma roller system
Guangzhou Vantee Electronic Technology Co., Ltd. , https://www.finerroller.com