The use and skills of specialty inks

Non-traditional lithographic offset inks, such as metallic inks, waterless inks, fluorescent inks, and opaque inks, have become increasingly popular among users as a design element and have the ability to improve internal throughput. 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 suit the specific situation to obtain the best print quality. This article describes some tips for using different specialty inks. It also describes how to choose the right fountain solution when using non-standard rubber, oil, and resin based inks.

Metallic inks Metallic inks are formulated from fine metal foils (aluminum foils are used for silver inks and copper foils are used for gold inks). When the inks are dried, these foils form a layer of stamped metal foil on the printed surface. When the metal pigment forms a thin layer on the surface of the print, it will produce a higher gloss of gold or silver ink. If you change the ink's metal flakes component or add color ink oil additives, the golden ink's color range will change from reddish gold to gold.

Metallic gold or silver inks have a long shelf life and do not lose their luster even if they are stored in a container for a year. However, the metallic inks in the PANTONE Metal Color Manual are not very stable and should be used as soon as they are bought or prepared. The use of softer particles for the formulation of metallic inks allows the metallic flakes in the ink to form a thin metal foil or to spread as far as possible on the surface of a single sheet of printing material for maximum gloss. Metal inks have low viscosity characteristics and are suitable for transfer between ink rollers, making the printing process cleaner.
The coated paper absorbs the fixed ink better, so the ink on which the ink is printed is the brightest. Smooth non-coated paper also gives better results, but the gloss is slightly reduced. The rough surface of the paper prevents fine metal ink particles from forming metal foil on the surface of the paper, thereby reducing the printing effect of the metallic ink.

Some substrates, especially polishing coating and clay-coated porcelain products, tend to hold the ink firmly on the surface of the substrate due to insufficient adhesion, often absorbing only the varnish in the ink. The particles stay on the surface. This phenomenon, known as "powdering," causes the color of the metal to peel off the surface of the substrate. To prevent "powdering", the amount of water should be set to a minimum, because inks with higher water saturation are more prone to "powdering." When printing on high coated paper or porcelain surfaces, an appropriate 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 clear white ink coated with a glue. If "powdering" has already occurred, printing another layer of ink on the surface of the first layer will often make up for this fault. Overprinting the varnish can also overcome powdering, but this tends to reduce the metallic luster.

Tip: For best results, it is recommended to use a metal plate instead of an electrostatic plate. This prevents the fountain solution from containing excessive amounts of glycerol or ethylene glycol because these non-volatile liquid media slow down drying.

The opacity of the metallic ink can cause the operator to compensate for excess ink, causing the ink to appear unbalanced. Should avoid this situation as much as possible, because it will give the dampening system too much burden, resulting in paste plate (ink particles emulsified in the fountain solution) and dirty (ink adhesion to the plate non-graphic section). Even experienced printers use the excess ink to achieve the perfect metal effect. The best way to prevent these malfunctions is to add ink to a lighter color image so that it covers the image exactly. Then, increase the amount of ink, and adjust the amount of water supply so that it is slightly higher than the minimum value, so as to avoid the non-graphic part of the ink. The thin layer of metal will protrude during the drying process, providing a brighter luster.

Fluorescent inks Fluorescent inks glow in dark environments. The key to this effect lies in the fact that the ink contains a special color pigment that absorbs energy in the ultraviolet region and converts this energy into longer visible wavelengths. 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 plate to the blanket, the blanket to the substrate.

Tip: Fluorescent inks are best for metal plates. It is best not to use light or colored paper when selecting paper, because colored paper will be reduced, and even the brightness of the ink will be minimized. White or bright paper will enhance the fluorescence effect. Non-coated papers with higher brightness and better ink absorbability are preferably fluorescent inks. Coated white paper can also have a more beautiful effect. However, since only a small amount of ink is used for printing with coated paper, it is necessary to perform two printings for the best printing effect.

Opaque inks Nearly all printers encounter printing on the surface of a black or colored object. For these types of substrates, an opaque ink is needed to effectively cover the color of the substrate itself. This avoids the mixing of the color of the ink with the color of the substrate, creating an undesirable color.

It is often impossible to accurately reproduce a bright color on a dark substrate. However, simply adding a 50% opaque white to a dark-colored substrate will result in some very imaginative sermons. It is recommended that if you use more than 50% of the opaque white, the printed colors will look "too light"; if less than 50% of the opaque white, the color will be a little transparent.

Tip: When using custom colors or PANTEDNE's blended colors, transparent white rather than opaque white is often required in recipes to minimize the loss of color intensity. In most cases, it is not necessary to replace all opaque white inks with clear white ink.

Waterless ink Recent developments in waterless printing inks have made it more characteristic of traditional offset inks. However, most water-free inks have high viscosity and thick texture. They do not spread smoothly when they are transferred in the ink roller, and they 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 out for 6-8 hours.

Tip: If a certain kind of 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 some time, it will harden, and raising the temperature will improve its fluidity. .

Non-traditional Ink and Recycled Paper Traditional quick-drying inks are ideal for front-side (or non-recycled) paper, but the same ink often causes problems when printing on recycled paper, especially when the ink is low (or small Range Surface). This is because light ink causes the ink to stay on the ink roller longer than when printing thick ink or large surfaces. When the ink is waiting to be deposited on the paper, there is a tendency for the ink on the ink roller to lose solvent and increase the viscosity. This high viscosity will pull out weak fibers in the recycled paper, affecting the normal printing process.

Tip: Vegetable oil inks have lower viscosity than high solvent-based inks. They also have better ink roll stability than high solvent inks, which keeps them low in viscosity throughout the printing process. This ink stability is reflected in the cost of slow printing, which means that it takes longer in the reprint. However, this is a reasonable transaction for achieving high quality prints on recycled recycled paper.

Choosing the right fountain solution Non-standard substrate inks are often incompatible with certain types of fountain solutions. Low-VOC or vegetable oil based inks are dried by oxidation. This means that equipment settings using this ink can be slower and take longer to dry. Using an alcohol fountain solution can speed up drying, but avoid the use of non-volatile wetting agents such as glycols.

For petroleum-based inks, because oil is easily absorbed by the paper, the machine can run faster and the drying time is shorter. This type of ink is suitable for use as a fountain solution.

Metallic inks can use all fountain solutions containing 10% to 15% isopropanol, all of which are suitable. It is recommended to use a fountain solution with a pH between 6.0 and 6.5 to make the printing of metal ink cleaner and more lustrous. One ounce of dampening activator should be added per gallon.

All fountain solutions are suitable for opaque inks. A 15% water-resistant varnish is added to the opaque ink with any fountain solution to improve fluidity and transferability, and to prevent "spotting". To ensure the best results, keep the pH of the fountain solution between 4.5 and 5.0 during the printing process.

Fluorescent inks usually have no special fountain solution, but alcohol fountain solutions work well for metal plates. The fluorescent ink requires a large amount of ink for printing. In the fountain solution, 20% alcohol is always added to obtain a good density value. Such a mixture can allow a large amount of water to evaporate and the oil layer is heavy and heavy.

The balance of ink and temperature in the waterless printing process replaces the ink balance, so there is no need to add fountain solution.

Tip: Adding less than one ounce of normal pure ammonia per gallon fountain solution (to ensure that it does not contain detergent-like substances) will increase the pH of the buffer.