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Non-traditional lithographic offset inks, such as metallic inks, waterless inks, fluorescent inks, and opaque inks, have become more and more popular among users as a design element and have the ability to improve internal production. When printing with non-traditional inks, the unique properties of each ink must be kept in mind so that the print settings can be adjusted to achieve the best results. This article describes some of the tips for using different specialty inks. It also describes how to choose the right dampening solution when using non-standard rubber-based, oil-based, resin-based inks.
Metal ink
Metallic inks are formulated from fine metal foils (aluminum foil for silver inks and copper foils for gold inks) which form a layer of stamped metal foil on the surface of the print when the ink is dried. When the metallic pigment forms a thin layer on the surface of the print, a higher gloss of gold or silver ink is produced. If you change the foil component of the ink or the additive of the tinted ink, the color range of the gold ink will vary from reddish gold to golden yellow.
Metallic gold or silver inks have a long shelf life and do not lose their luster even after being stored in containers for one year. However, the metal ink in the PANTONE Metal Color Handbook is not very stable, but should be used as soon as possible after purchase or preparation. Softer particles are used in the preparation of metallic inks, so that the foil in the ink can form a thinner metal foil or spread as much as possible on the surface of a single substrate to achieve maximum gloss. Metal inks have low viscosity properties and are suitable for transfer between ink rollers, making the printing process relatively clean.
The coated paper absorbs the fixing ink better, so the ink on the printing is the most vivid. Smooth uncoated paper will also give better results, but the gloss will drop slightly. The rough surface of the paper prevents fine metal ink particles from forming a metal foil on the surface of the paper, thus reducing the printing effect of the metallic ink.
Some substrates, especially polished and clay coated porcelain, have insufficient adhesion to hold the ink firmly on the surface of the substrate, often only absorbing the varnish in the ink, while the metallic pigment The particles remain on the surface. This phenomenon known as "pulverization" causes the metallic color to peel off the surface of the substrate. In order to prevent the "powdering" phenomenon, the amount of water should be set to a minimum, because the ink with higher water saturation is more likely to be emitted. "Powdering". When printing on high coated paper or porcelain surface When appropriate, a suitable amount of desiccant should be added to the ink. Before printing with gold or silver ink, the surface of the substrate is usually sealed with a conventional oil-based transparent white ink coated with a sizing. If the "pulverization" phenomenon has occurred, Reprinting a layer of ink on the surface of the first layer will often make up for this fault. Printing varnish can also overcome the pulverization, but this will tend to reduce the luster of the metal.
Tip: For best results, it is recommended to use a metal plate instead of an electrostatic plate. This will prevent the fountain solution from containing excessive amounts of glycerin or glycol, as these non-volatile liquid media will slow down the drying process.
The opacity of the metallic ink causes the operator to compensate for the excess ink, causing the ink to become unbalanced. This should be avoided as much as possible because it puts too much burden on the dampening system, which leads to paste (ink particles emulsified in dampening solution) and dirt (ink adheres to the plate) section). Even experienced printers use the most ink to achieve the perfect metal effect. The best way to prevent these problems is to add ink to a lighter image so that it covers the image. Then, increase the amount of ink and adjust the amount of water supply to a little above the minimum value to avoid non-image portion inking. A thin layer of metal protrudes during the drying process, providing a brighter luster.
Fluorescent ink
Fluorescent inks illuminate in dark environments. The key to this effect is that the ink contains special color pigments that absorb energy in the ultraviolet range and convert these energy into wavelengths of longer visible colors. The surface of the print can emit a strong, saturated color that attracts attention. The constituent particles of the fluorescent ink are generally softer than other oil-based or rubber-based ink particles. But this does not affect its performance, because they have a unique transfer method during the transfer of the drum and the drum, the printing plate to the blanket, and the blanket to the substrate.
Tip: Fluorescent inks are best for metal plates. It is best not to have light or colored paper when choosing paper, because the color of the paper will be reduced, and even the brightness of the ink will be minimized. White or bright paper will enhance the fluorescence. Non-coated papers having higher brightness and better ink absorption are preferred for use with fluorescent inks. Coated white paper can also have a more beautiful effect. However, since only a small amount of ink can be used for printing with coated paper, it is necessary to perform two printings in order to obtain an optimum printing effect. Opaque ink
Almost all printers encounter printing on the surface of black or colored objects. For these types of substrates, an opaque ink is needed to effectively cover the color of the substrate itself. This avoids mixing of the color of the ink with the color of the substrate to create an undesirable color.
It is usually impossible to accurately replicate a bright color on a dark substrate. But simply adding 50% opaque white to a darker substrate will receive some very interesting evangelistic effects. I suggest you: If you use more than 50% opaque white, the color printed on the back will look "light"; if less than 50% opaque white, the color will be somewhat transparent.
Tip: When using custom colors or PANTEDNE blend colors, transparent whites rather than opaque whites are often required in the formula to minimize color loss. In most cases it is not necessary to replace all opaque white ink with clear white ink.
Waterless ink
Recent developments in waterless printing inks have given it more of the characteristics of conventional offset inks. However, most anhydrous inks have a higher viscosity and a thicker texture. They are not easily spread smoothly in the ink roller and will harden or dry on the surface of the ink roller. The best water-free inks are those with a wide temperature range. The ink -- between 72 and 92 ° F -- and has the ability to dry for 6-8 hours.
Tip: If a certain waterless ink loses its viscosity due to the long running time, lowering the temperature will increase the viscosity of the ink itself; if the ink stays on the ink roller for a while, it will harden, and raising the temperature will improve its fluidity. .
Non-traditional inks and recycled paper
Conventional fast-drying inks are well suited for front side printing (or non-recycled paper) of paper, but the same inks tend to have problems when printed on recycled paper, especially when the amount of ink is small (or a small range of surfaces). This is because light ink causes the ink to stay on the ink roller for a longer period of time than when printing thick ink or large surfaces. When the ink is waiting to be deposited on the paper, the ink on the ink roller has a tendency to lose solvent and increase the viscosity. This high viscosity pulls out the weak fibers in the recycled paper, affecting the normal printing process.
Tip: Vegetable oil inks have a lower viscosity than high solvent based inks. They also have better ink roller stability than high solvent inks, a property that allows them to maintain a low viscosity throughout the printing process. This ink stability is reflected in the slow printing process, which means that it takes longer in lithography. However, this is a reasonable transaction for achieving high quality prints on recycled paper.
Choose the right dampening solution
Non-standard substrate inks are often not compatible with certain types of fountain solutions. Low-VOC or vegetable oil-based inks are dried by oxidation. This means that equipment settings using such inks can be slower and take longer to dry. Use alcohol dampening solution to speed up drying, but avoid using non-volatile wetting agents such as glycols. For petroleum-based inks, since oil is easily absorbed by paper, the machine can run faster and have a shorter drying time. This ink is suitable for use as an dampening solution for alcohol substitutes.
Metal-based inks can be used with all dampening solutions containing 10% to 15% isopropanol. It is recommended to use a dampening solution with a pH between 6.0 and 6.5 to make the metal ink print more clean and shiny. One-half ounce of dampening activator should be added per gallon.
All fountain solutions are suitable for opaque inks. Add 15% water-resistant varnish to opaque inks with any dampening solution to improve flow and transfer and prevent "spots". To ensure optimum results, the pH of the dampening solution should be between 4.5 and 5.0 during the printing process.
Fluorescent inks usually do not have a special dampening solution, but alcohol dampening solutions work well for metal plates. The amount of ink required for printing fluorescent inks is large. In the dampening solution, 20% alcohol is always added to obtain a good density value. Such a mixture can allow a large amount of water to volatilize and the oil layer is thick.
In the waterless printing process, the balance of ink and temperature is used to replace the ink balance, so it is not necessary to add a fountain solution.
Tip: Add less than one ounce of normal pure ammonia per gallon dampening solution (to ensure that no detergents are included), which will increase the pH of the buffer.