Reference points for color silk printing
it is a hard won technology for any silk printing enterprise to produce high-quality four-color graphics. Because hundreds of possible variables interfere with the printing process at any time and users use different standards to evaluate the printing accuracy, every enterprise often does not know the way to successfully carry out four-color printing. As a result, it is almost impossible to find out that any two silk printing operations will print four colors in the same way or achieve similar results when providing the same print
on the one hand, most competitive imaging methods use standard procedures and industry recognized tolerances to guide them through every step of the printing process. On the other hand, graphic silk printing operations usually rely on instinct and repeated experiments to establish the production standards of printing operations. Worse, these standards and procedures may change with each print they print
this inconsistent image reproduction method has prompted researchers and silk printers all over the world to study the standards of color silk printing. The standards published by the international organization for Standardization (ISO) set the tolerances and goals that silk printers should meet at each production stage when printing color graphics
there are two commonly used ISO standards for color silk printing and a general ISO standard for silk printing to strive to build an aerospace new material industry base and a national military civilian integration demonstration base. The first color silk printing standard involves quality measurement and control when making samples and producing prints with a platform or roller silk printing machine. The second standard concerns the color characteristics and transparency that four-color silk printing inks should have. The last standard determines the internationally recognized technology, which describes the tools and businesses used in color silk printing
find out how ISO standards came into being and why they are understood so slowly among American silk printers
first bill Appleton, then a lecturer and silk printing teacher at the University of art and technology in Gloucestershire (Gloucester, UK) put forward the basic principles of the standard in the UK in about 1990. Due to the lack of useful information on color graphic silk printing, Appleton believed that there must be a standard applicable to silk printing
for this reason, Appleton contacted the British Silk Printing Association (SPA) and expressed his ideas. The association suggested that he lead a working group to investigate this possibility, and then the British standardization plan was born. Appleton said, "many people think that we cannot formulate the standard of silk printing, but in the first six months, we have received support from every major British ink manufacturer, template manufacturer and supplier."
Dr. Timothy Klebold, director of the Welsh Centre for printing and coating at the University of Wales Swansea, pointed out that the importance of developing standards is increasing, "because people feel that if they want to improve graphic silk printing, they must be able to understand it."
in 1994, after several experiments, more than 1000 measurement data were obtained from color prints from many factories in the UK and other sources, so the point increase curve, tone correction curve and the smallest printable point size were determined. The working group used this initial standard to print its first print. "Then we submit what we think is a British standard to the British Standards Institute," Appleton said. Because Britain is a member of the European Union, the society strives to promote unified standards among all member countries, and requires researchers to submit their standards for evaluation to DIN, the German Institute for standardization
when members of the UK working group contacted the German Standardization Association, they learned that their German counterparts have been working on the same standard for almost 8 years. "They really don't intend to publish our results on top of the results of their German counterparts, so we decided to face the world." Appleton said
in order to help convey standards to international peers, the silk printing association is involved. The Association confirmed that although some detailed work needs to be done, the work of the working group forms the basis of the standard. The silk printing association also told the working group that its research should be free from copyright restrictions as part of the process of submitting it to the international standards body TC130 (ISO Technical Committee responsible for graphics technology). The ISO Technical Committee Working Group not only accepted the draft standard, but also invited the UK working group to its next meeting
in order to determine whether the print meets the tolerance specified in the ISO standard, the printer should make a measurement and control strip and its imprint (see Figure 1, there is a ladder figure on one side of the image). Evaluate the results with a densitometer to determine the point increase, and measure the color density and related values with a spectrophotometer
the TC130 committee meeting was held in Berlin in the autumn of 1994, which provided the first major opportunity for the progress of the work. There, members of the UK working group had the opportunity to sit down with representatives of the German standards working group to share their research results. Appleton recalled, "we thought it might be difficult to pass." However, he pointed out that there was no conflict between the experts of the two countries because the data of the UK involved capillary film, template and roller printing machine, while the research focus of Germany was on direct milk, which had huge industrial development space
in 1995, standards research working groups from countries around the world (such as Japan, Brazil, Germany, figure 1, the United Kingdom and the United States) gathered to compare the views of all parties. Dutchdrehle, a senior technical deputy of the international silk printing and Graphics Association (SGIA), recalled, "everyone in the working group has done some research on four-color printing. In some cases, we are very close, and sometimes there are differences. Therefore, we discuss, negotiate and limit those parameters to the range that everyone can control."
before you get the four-color printing standards and need your supplementary comments, remember that these standards only specify the tolerance, acceptable range, value and benchmark. A standard can contain several related topics. Therefore, some ISO standards are divided into several parts. This method organized by ISO allows some relevant personnel to buy only the text they need (the standard is divided into paper text and PDF document), and helps reduce the research on related topics. The standards are briefly described here
iso:2000 this standard is divided into several parts: sheet fed and thermosetting web offset lithography, cold set offset lithography, publication gravure printing and silk printing. Standards for flexographic printing and digital printing are being worked out. The fourth part of this standard, silk printing, specifies the color and transparency produced by color inks, including fillers for four-color printing. This standard also describes the test methods used to ensure consistency. As kleiper pointed out, "it specifies the points in the color space that ink should be able to approach. It also specifies how to approach within a certain tolerance."
iso:2000 is suitable for ordinary drying and UV drying silk printing inks. It specifies the l*a*b* value and density requirements, but does not determine the pigment or spectral reflection coefficient. In other words, printers can use inks with different pigment combinations to meet the standard chromaticity requirements. They can also use their favorite printing materials to meet the standard density specifications
iso: the fifth part of 2001 ISO 12647 mainly deals with the process control of color silk printing. Topics include hue value range, hue gain curve, point frequency and angle, point characteristics, gray balance control, positive negative transmission density, and so on. This standard specifies the minimum acceptable tolerance and the target value that the printer can achieve. In order to ensure that positive negatives and prints meet the standards, color separation and printing must be generated together with the eye tone test strip (Figure 1). Printers use densitometers to measure the size of evaluation points of measurement and control strips and spectrophotometer to measure color characteristics. Use the measured value to adjust other parameters related to the point increase (Figure 2) and inconsistent with the acceptable tolerance. Klepper said, "on every print, you will have a test strip and a color scale, which will give you quality assurance. To identify the tone gain curve of the printer, you also need to make test samples."
this standard also helps to establish a common language between vendors and customers. It protects both when they agree on parameters within a specified range. "If the printer is ready to print according to the standard and wants to meet this standard, he can quantify whether the goal of selecting standard tensile samples has been achieved, whether the point size is appropriate, and whether the density is appropriate. It can be measured, which fundamentally eliminates any debate. If the print is printed by consensus, the customer can't go back and pick something wrong on the print out of nothing, so as to reduce the price of the printing operation. Legally Said this is helpful for both printers and customers. "
iso:2001 another commonly used standard for silk printing is iso:2001, which determines the multilingual terminology of silk printing as a whole, rather than focusing on four-color printing. This standard stipulates the internationally acceptable technical language. Apolton said that it is important because the meaning and scope of silk printing terms may vary from country to country. Purchase orders are legally binding contracts in some parts of the world. When they use standardized languages, screen printing industry becomes more suitable for global business practices
tc130 is currently revising this standard. The newly revised standard will include all printing technology and basic terms (), prepress technology terms (), printing technology terms (12637 - 3 and should be able to apply the maximum force of the testing machine to the sample), and post press processing technology terms (). If the new standard is adopted, iso:2001 will be withdrawn
i s o standard specifies the parameters that should be adopted by the printer when correcting the dot increase that occurs during printing. Programs such as Adobe Photoshop graphically describe the tone curve and allow users to modify the point size in the original, so that the tone generated by the printer is accurate and improved in a linear manner
in the United States, drehle is responsible for collecting data from the silk printing industry (including manufacturers and printing enterprises). One of the printers he came into contact with was bron Wolff, a silk printing technology expert at West Bend sengraph Co., Ltd. Wolff agreed to incorporate the technical specifications into the relevant testing standards and help erehle collect feedback from other printers. Wolff recalled that most of the screen printing brush manufacturers he came into contact with did not understand what standards meant
in order to evaluate this standard, Wolff extracted ink samples from five manufacturers and tested them. He found that some manufacturers have twoorthree kinds of color inks that meet the technical specifications of the ink standard, but none of them is a full set of four-color CMYK inks that meet the standard. According to Wolff, another potential problem is the performance effect of ink
some inks are prepared for printing on special substrates. He said, "the ink printed on vinyl is better, but the ink printed on Coroplast is not good, because they add more light."