Precautions when printing with gold and silver ink

The use of gold and silver ink

When gold and silver inks are printed, the choice of printing materials is very critical, because there are many pores in the surface, and the substrate with permeability will absorb the transparent resin liquid, especially when the viscosity of the ink is low, the resin is absorbed and the pigment particles will be Leaving on the surface of printing materials, the resin composition is small, will cause the silver powder to appear gray, and the gold powder will appear brown. If there is no other choice but to use absorbable printing materials, it is best to print a layer of ink (like traditional transparent varnish) to seal the pores on the surface of the substrate and then print the gold on it. Silver ink. A layer of varnish is applied over the metallic ink film to resist peeling and abrasion of the particles in the ink. However, the more transparent polish on the metallic pigment particles, the weaker the reflective performance and gloss of the ink film.

Metal pigments are easily oxidized. Take powdered pigments as an example. Oxidation occurs on copper and zinc particles, resulting in a reduction in the gloss of the ink layer. In some cases, the ink may even appear light green. The aluminum pigment in the silver pigment easily becomes gray and white after oxidation. Oxidation is one of the reasons why the color consistency of gold and silver inks is difficult to achieve.

Another reason for the inconsistency of color consistency is the arrangement of pigments, especially layered gold-silver ink, which floats on the surface of the ink film and forms a lot of voids (the larger the size of the color particles, the larger the gap). After printing, the appearance of these small voids allows the color of the substrate or the underlying ink color to be visually morphed through the surface color of the metal layer. For example, a silver ink in a blue background will appear light blue; if gold ink is preprinted with a yellow or green ink film, the ink's gold color will be changed. Using non-color such as white or light gray as the base color can alleviate this problem. Silver pigments usually exhibit a dark hue, and gold powder can not only show dark hue, light hue, and various hue between the two, but also can be used to obtain a series of "oxidized hue", meaning that the pigment allows and controls conditions The resulting oxide reacts and the reaction results include gold tones with lemon yellow or light orange.

Gold powder pigments can also produce light shades such as green or purple, which are obtained by adding various color pigments to the gold powder ink. However, these colors are more unstable and appear to be incongruous compared to pure metallic colors, and are also prone to fading.

Light-colored silver powders often use transparent colorants so that they look like powdered gold pigments. This method also solves the oxidation problem of gold powder. Such silver powder can be used for non-layered glossy ink, but the color is not as clear as the standard layered silver ink.

In addition to traditional colors, most color systems point to a series of metallic inks. A silver metallic pigment is used as the base color and then colored with a red, yellow or orange ink. The challenge for making this type of ink is that some of the red, orange, and yellow pigments used for color matching may react with metallic pigments, thus destroying the printed graphics. Producers need to be extremely careful when deploying metal colors to avoid the above problems.

The use of tinted gold and silver inks increases the area of ​​coverage and allows the specific color to be formulated more accurately. However, some of the ingredients added to the tint will reduce the gloss of the gold and silver pigments. When the customer proposes the maximum reflection capability as a condition, it is recommended to use dark colors, pale gold colors, and silver powder in the purest form. Another factor that affects post-print gloss is the color purity or clarity of the resin used to make the ink. The higher the clarity of the resin, the more reflected light and the better the gloss of the ink.

When discussing the appearance of gold-silver ink, we should note a phenomenon: Since metal pigments are used in gold and silver inks, the appearance of the ink film after printing will change with the viewing angle. This is why it is generally not recommended to use traditional printing spectrophotometers to measure gold and silver prints. The accurate measurement tool is a spectrophotometer for the automation industry. The device recognizes colors from multiple angles and finally obtains an average value, which can accurately determine the color, but the price of such a device is usually unacceptable for a screen printing company.

The metal pigment particles are purchased separately from the binder and are very slow and careful when mixed; because the rapid mixing generates heat, it promotes oxidation, causes the metal flakes to decompose, turns silver into gray, turns gold into brown, and Reduce reflection and gloss.

The proportion of the pigment mixture varies depending on the size of the pigment flakes and is also related to the desired ink film after printing. Generally speaking, it is safe to start mixing with 8% silver pigment or 15% gold pigment by weight. According to the ink manufacturer's recommendations to ensure the ink adhesion and appearance.

If possible, using the least pigment should be the best. Because the result will be better ink transfer properties and higher durability. Many printers think that adding more pigment powder to the mixture does not increase the gloss of the ink. The fact is that the smaller the number of pigments, the better the adhesion, and the more uniform the ink film, the more uniform it means that the smoother the surface, the better the reflective performance and, of course, the better the gloss. Therefore, the minimum amount of pigment should be used to meet the target color and coverage area.

When mixing silver inks, extreme care must be taken if the aluminum pigments are in powder form. Because aluminum powder reacts with water or moisture to release hydrogen, it can cause an explosion. Therefore, if you insist on using aluminum powder to make silver ink, you must ensure that the aluminum powder is stored in a dry, suitable temperature place. In contrast, the presence of aluminum as a paste is relatively safe, and all aluminum powder producers also supply paste-like pigments that are compatible with various forms of solvent-based, water-based, and UV-dried inks.

The Future of Screen Printing Gold and Silver Ink

Screen-printing ink makers are still working hard to refine gold and silver inks, making them easier to use and producing shocking results. In recent developments, metallic effect ink types have included new effects that provide the same appearance as chrome plating. But in order to get a real example of the chromium effect, the printer must carefully test to determine how much pigment is needed. The less commonly used pigment, the better the effect.

Gold and silver inks, especially silver inks, are completely impervious to radiation and this feature makes them ideal inks for screen printing applications, such as selective blocking of light in certain instruments. However, when metallic silver, which is highly reflective, is used as a protective coating, the color of the graphic printed thereon will change.

The good effects of screen printing of gold and silver inks can increase the value of many products related to prints, including binding, labeling, packaging decoration, and eye-catching graphics.

As with any other product, screen printers understand the composition, production process, and performance limitations of gold and silver inks. They can introduce the advantages of such inks to customers as much as possible. Therefore, gold and silver inks are printed. Another golden opportunity!

Reprinted from: Chenyi Printing Network