The most complex and arduous research on the print

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The complex and arduous research on paper printability

"paper printability test", referred to as PPT (paper printability test), is an evaluation project led by the China Association of publishers. After more than two years of rigorous testing and research work, it has formed a certain influence in the publishing and paper industry, gradually becoming a bridge connecting the publishing, printing and paper industry, and a generally promising project serving scientific research and market

even if the quality of printing paper is relatively poor, it mainly affects the printing effect, that is, the visual image, which generally will not hurt people, which is different from daily consumer goods such as moon cakes and washing powder. Therefore, the detection of printing paper cannot be expected to attract the attention of the general public. It is only publishers and printers, as well as paper manufacturers, who are concerned about it. It is a small group of people with strong professionalism. However, no matter what is tested, such elements as professionalism, standardization, objectivity and impartiality cannot be omitted. As for authority, it is public opinion, not what the tester can flaunt

the experiment should carefully avoid common sense

the "paper printing suitability test" (PPT for short) done in December 2005. Its experimental design has undergone major adjustments, and there are two substantive adjustments: first, the final evaluation of the paper printing suitability is based on pure visual inspection, and the technical data is only listed as an appendix; Second, follow-up laboratory tests should be carried out on the paper with the best and worst visual inspection results

the previous practice was to send printing samples with laboratory data and printing data to experts for evaluation. The experts' opinion was to visually observe the comprehensive judgment of various data. The current practice is that before experts make visual evaluation, they do not touch any data, without any interference, and make a conclusion only based on the visual effect, and then decide which papers to continue to be tested in the laboratory according to the conclusion. Because we have determined that independent and pure empirical judgment is the most important for PPT

printability is a very complex problem. As an elder in the printing industry lamented: the problem of printability is still unclear up to now, because there are too many factors affecting the printing effect. The combination of personnel, equipment, materials, technology, environment and other factors must be a complex system. The idea of PP t is to study the factors of paper. The method is to combine paper with different properties with stable printing process, compare the differences of their respective printing effects, and then deduce the influence of various properties of paper on printing effects. According to this idea, the performance of the paper participating in the test is fixed, but its value is undetermined and needs to be investigated. Logically, undetermined factors should not participate in the evaluation of themselves. For example, to determine the impact of paper whiteness on printing effect, we can't judge it by our knowledge about whiteness, but by the correlation between whiteness and printing effect. Thus, a visual judgment independent of any previous common sense is the only credible reference

theory comes from experience (or practice). Theory can be close to correctness only through repeated correction with experience, without exception throughout the ages. P P T is to get the explanation of paper printability through this mutual calibration process. We should carefully avoid common sense and previous prejudices, combine the wisdom and labor achievements of our predecessors, and use scientific research methods to conduct P P T, which is a good starting point

isolated factors and combined system

after we have completed the visual inspection and published the test results, the test research on paper will continue

in January, 2006, we sent the 20 kinds of paper with the best and worst printing effect to the laboratory for testing. As a result, the consistency between the previous comprehensive evaluation and technical data has disappeared, and instead there is some confusion

Table 1, table 2 and table 3 show the relationship between printing effect and technical data. The technical data in the table is sorted from top to bottom according to the order of common sense, and the number is the ranking of visual printing effect

what is good for our common sense? It is high on-site density, high K value, low through printing density, dot gain size, low ink absorption (for uncoated paper), high surface strength, and low surface roughness (P P, the purchase price of some steel mills continues to decline s). What do we see in the table? Among the 21 groups of indicators, except for the "field density" of 3 groups, the "ink absorption" and "PPS" of light paper, which show consistency with the printing effect, the other 16 groups are inconsistent with the ranking of the printing effect, or even have no regularity. Scientific research is about facing facts and accepting facts. For this result, I don't doubt the ranking of visual printing effect at first, because it was determined by experts after careful comparison and reaching a preliminary agreement on the maximum load required for tensile specimens; Secondly, I don't doubt the effectiveness of common sense of a single technical index, because that is the conclusion reached by studying an index in isolation. What's the problem? After analysis, I think it should be based on the combination and matching of paper performance. Just like the prescription of traditional Chinese medicine, the same drugs have different curative effects with different doses. In a combined system, the law of the original isolated factors will give way to the comprehensive action of many factors. For example, the higher the K value, the better the printing effect. The role of K value may not be as big as we think, and it may be covered by some stronger factors. As for which factors are strong and which factors are weak, this is what p p p t wants to study. In the final analysis, as a scientific research, PPT is a kind of correlation research, not a decisive research

from the above data relationship, the printing density of various papers has maintained a high correlation with the printing effect, which is basically not disturbed by other factors, indicating that keeping more ink on the surface of the paper and increasing the thickness of the ink layer is an important focus and a strong factor to improve the printability of the paper; For light-weight paper with relatively rough surface, it may be an effective way to improve printing density by reducing ink absorption and roughness, which is consistent with the general characteristics of light-weight paper we know. As for those chaotic data, I think there is no law, but a superficial phenomenon, which is caused by insufficient data accumulation. Some hidden laws can be summarized by statistics through more experiments, repeated analysis and comparison, and there is no quality without quantity. Of course, the project team also needs to carefully check whether there are out of control factors in the control of experimental conditions, and further study the design of the experiment according to the data, so as to find clear clues to go deep. The data presented here just shows the complexity and arduousness of the research on printability, and the goal is still far away

finally, table 1-A, table 2-A, table 3-A of the measured data related to table 1, table 2, table 3 are attached for the reference of interested colleagues and hope to get advice. Among them, the laboratory data is published for the first time

related links about ppt

(1) the "paper printing suitability test" (hereinafter referred to as "ppt") mainly organized by the China Association of publishers has been done for more than two years, and the relevant process and results have been published in the Journal of printing quality and standardization

(2) four issues of "Beijing paper purchasing catalogue with simple operation and other characteristics" were published and distributed free of charge within a certain range

(3) as the stage summary of PPT, in March, 2006, the printing industry press published the book "paper printing is suitable for the detection and research of spring manufacturers, low-voltage electrical appliances, power machinery plants, colleges and universities and scientific research institutions"

(4) the introduction and comments on PPT can be found in newspapers and periodicals such as China publishing news

source: business information of printing materials in China

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