Analyze printer ink and paper (bottom)
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How do you see the coating thick? Print with the same amount of ink, if the density of the dark part is the same, and the middle color is the paper with a thin coating or a large dot spread. After increasing the amount of ink, the paper with a small density in the dark portion is definitely a paper with a serious dot spread or a thin coating.
Since the coating is completely transparent, the ink can form a large concentration, and the incident light is reflected after being reflected to the bottom layer, and after two filtrations, exhibits high color saturation. Further, since the dot spread is small, the color can be colored to the maximum by a pure coloring method, so the saturation of the high-brightness red, green, and blue is very high.
The "glue" coating also has soft and hard parts. The "hard" coating touches the surface of the plexiglass, the ink absorption is slower, and the type of ink is also relatively picky. The solvent of the ink is not suitable for absorption. However, its ink droplets are small in diffusion, and the ink layer formed is thick and can print the best photos. It does not absorb the original ink of EPSON original ink, Canon original ink and some HP printers.
The "soft" coating feels awkward, like touching the surface of a balloon. The ink absorption speed is very fast, and almost any ink can be absorbed. But different papers have a great change in the color of the same ink. One type of paper performs fine on EPSON printers, but it turns blue on HP printers. We estimate that the diffusion rates of inks of different compositions are different. The reason for the bluishness may be that the blue ink diffuses less, and the other colors are heavily diffused. The dot spread of such papers is usually relatively large, and the softer the paper, the better the ink compatibility is. The sharpness and color saturation of the picture is also worse. I suspect that this type of paper creates a lot of tiny pores in the "glue" to absorb the ink quickly. The greater the proportion of voids, the better the ink absorbency, which feels like a foamed plastic (or a foamed "glue"). However, the micropores cause the ink dots to diffuse greatly, and the transparency of the coating is lowered. Therefore, the "soft" paper printing effect is close to the coated paper, which is not beautiful enough.
The clear coated paper is only returned when the light hits the bottom layer of the white reflective layer. The incident light is filtered by the dye layer, so the color saturation is highest. In the translucent or opaque coating, the light is halfway through. The folds are successively folded and are not sufficiently filtered by the dye, so the saturation, maximum density, and darkness are not as good as the clear coat.
The strange thing is that "soft" paper usually has a certain waterproofness. It is possible that it absorbs ink mainly by its micropores instead of "glue", so its "glue" can be insoluble in water, so there is a certain Waterproof. The surface tension can be specially modulated so that it can only be infiltrated by a specific ink, and the ordinary ink is placed on it like a falling leaf, and it is impossible to enter the micropores to carry the ink out.
If the soft paper is indeed this structure, its fading resistance is not so good. Hard paper without film will not fade in indoors for 3-5 years, how about soft paper? I don't use much, what is your experience?
Since "hard paper" may absorb ink into its molecular structure, temperature and humidity have a great influence on the speed at which it absorbs ink. When the room temperature is lower than 20 degrees and the humidity is very low, there are many large particles in the dark portion where ink accumulation occurs due to inability to absorb ink in situ. When the room temperature exceeds 30 degrees and the humidity exceeds 80%, the photo will turn yellow again. The reason for this is still unknown. The most suitable temperature and humidity for using "hard tape" should be 25 degrees temperature and 50%-80% relative humidity. Paper with microporous ink is generally much less environmentally demanding.
Paper made from light boxes is usually more demanding. Because the light box requires a maximum density of 3.0 to look good. The incident light is only filtered once on the ink layer, and the density and color saturation appear lower. Transmissive sheets made by inexperienced people and those who use inferior light box papers are often gray, probably due to insufficient ink.
Printing a transmissive sheet usually requires twice the amount of ink when printing a reflective sheet. This is not only a requirement for software, but also a higher requirement for printing paper. The paper on which the transmissive sheet is printed has both transparent and back-transparent paper. The transparent sheet can only be used for transmission, such as on the projector, so it is used less, and few people work hard on the transparent sheet. Its ink absorption is not very good, and it is difficult to absorb twice the ink. the amount.
Printed transmissive films mostly use semi-transparent back-spray films, which can be used for both transmissive viewing and reflective viewing. They are not widely used when making light boxes, so they are widely used. The main quality indicators of the back spray are ink permeability and ink absorption.
Good back sprays have consistent ink permeability for all colors. However, we have seen that most of the poor quality back sprays always have a few colors of ink that are not transmitted well, so that the color is not accurate when the backlight is not used. Most of the cheap back-jets have poor ink absorption. When printing with twice the amount of ink, the maximum density does not increase correspondingly, and the contrast and sharpness of the picture are greatly reduced. In the general concept, the back spray is also divided into two types of powder and gel. We think this should also be the difference between using small holes to absorb ink and structure to absorb ink. Glue paper has great selectivity for ink, but good gel paper has strong ink absorption and can reach a maximum density of 3.0 or more. Powder paper has medium ink absorption, usually less than 3.0 density, and a density of 2.3 is very good. However, silty paper generally has good ink permeability, and cheap gel paper has poor ink permeability.
What is the main cause of fading?
Printing photos with a printer The biggest concern for people is the fading problem. According to our observation, the main cause of fading is light-heat plus air. And this air has the greatest effect. In addition to oxygen in the air, what is the biggest influence on color is not known.
In the case of no filming, “hard-adhesive paper” printed photos will not fade after being placed indoors for 3-5 years. Pictures printed on materials such as coated paper and rice paper that are very porous and have a very large surface contact with air have severely faded in 1 year. The film-coated “hard-adhesive paper” photo is only slightly faded in the indoor sun-facing side for half a year, and there is no visible fading in one year or even two years when it is not exposed to sunlight. But if the paper base is not plastic coated but breathable, the shelf life is reduced by at least half.
Take the printed photo that has been covered with the film for direct outdoor exposure, and save the shelf life by half. We once posted the printed image to the car in the summer, and after running for a month outside, the color faded. This shows that the car's hot iron shell is extremely damaging to color. However, if the photos are placed in an ultraviolet lamp and an ordinary incandescent lamp, there is no significant difference in the speed of their fading. Therefore, the most important thing to keep photos for a long time is: 1. Let the dyes insulate the air; 2. Rarely see high-temperature glare.
The pigment ink is more durable because it has larger particles and is less susceptible to oxidation inside. Some mineral pigments are inherently stable, such as cinnabar, but it is not possible to use as ink for printing.
Relationship between particle size and printing paper
The same printer, even with a replacement ink, has a small change in grain size. Related articles have also introduced the impact of software on granularity. So does the paper have any effect on the graininess? there must be.
In general, the paper with a large degree of dot spread is relatively large, and the principle is not difficult to imagine. But in many cases the opposite is true. For example, someone gave us a sample of paper, and we found it to have a very small particle size after printing. I was trying to make a lot of customizations to him, but the sharpness of the photos caused us to be suspicious. A close look at the microscope with a 50-fold microscope revealed that the dot spread of the paper was extremely severe, and the color of the dots was diluted (like the "flat particles" on the film), so it appeared to be fine. In opaque or translucent coatings, this phenomenon is more common, often with the finer paper particles appearing more densely diffused. Therefore, it is a comprehensive observation and selection to observe the granularity of a paper while observing its sharpness, color saturation, maximum density, and whether the dark part is down. This observation should be extended to the printing system. Because some printer systems let you choose only a few types of paper.
Is the printing software likely to change the printer's adaptability to paper?
However, we found that the software's improvement on the paper's adaptability to paper is limited. When you have already lowered the printing speed, there are a lot of ink beads that absorb unevenness in the dark part, and then use software to change the dot distribution. No use. Even a 50% reduction in speed at this time has no decisive significance. Therefore, basically do not believe that the use of certain software can improve the paper's adaptability.
Role of film
Many people are reluctant to accept the process of photo filming. Always emphasize how traditional photos are. But can traditional photos without filming touch? Can it be durable? According to our observations, the traditional photo preservation period without film is only half of the film print.
The first major effect of the film is waterproof, which is not necessarily required for traditional photographs. The second major role is to prevent fading, which is required for both traditional and print photos. The film also has an important role that many people may not find, because they use the cheap film.
Applying a photo film with a low refractive index to the photo can greatly reduce the reflection of the photo and increase the permeability. It has the same effect as the lens coating. Do not believe you give it a try.
However, the film is too much trouble, and it will get dust inadvertently. If anyone can invent a simple and high-quality film coating process, that is, it can cover the film while printing, it will definitely be very popular. We are still looking forward to it!