In product packaging and label printing, gold ink is often used to achieve the printing of golden graphics and text, giving people a delicate, gorgeous, and noble feeling. As a special printing method, gold ink printing differs slightly from ordinary ink printing methods in terms of the use of printing materials and process operations.

1. Gold ink blending

Jinmo is made by mixing and blending gold powder, gold oil, and a small amount of auxiliary materials. Ordinary colored ink is stored in a paste form in a tank, while gold ink is usually stored in two different containers with two substances, gold powder and gold blending oil. When printing with gold ink, the gold ink is then blended in proportion (usually the ratio of gold powder to gold blending oil is 1:1). At present, there are also pre configured gold ink supplies on the market that can be directly printed. But printing factories need to consider factors such as the amount of ink used in the layout, printing cycle, and product quantity when using it. Because the printing performance of gold ink will change and lose its original metallic luster after 1-2 hours of use, it is better to adjust and use gold ink printing as needed.

2. Gold ink printing technology

Gold ink printing generally uses neutral or neutral hard type liners, and the pressure of the ink roller on the printing plate cannot be too high, otherwise it will cause the phenomenon of plate sticking.

During printing, the gold ink layer on the printing plate often experiences insufficient ink volume or even exposed substrate during the transfer process to the surface of the paper or other substrates. Therefore, in order to achieve saturation of the gold ink and fully demonstrate its unique metallic luster, secondary printing methods are generally used. There are basically two methods of secondary printing currently used: one is to first print fake gold ink as the base color, and then overlay the gold ink; The second is to directly print gold ink twice. The fake gold ink used in the previous method is generally blended with two types of yellow ink: transparent yellow or medium yellow. If the paper is loose and has poor flatness, the fake gold ink should be mainly medium yellow, and an appropriate amount of gold ink should be added. If the paper is tight and smooth, use transparent yellow with a small amount of gold ink to mix the fake gold ink. When printing, the amount of ink on the base color should be as small as possible, with the principle of not exposing the base or seeping edges. When the base ink is not completely dry, reprint the gold ink with a slightly larger amount of ink to achieve saturation of the gold ink. When using the latter method, it is also important to emphasize that it is advisable to reprint the second layer of gold ink before it has completely dried. This is because the gold powder in the gold ink is a metallic pigment, and if it dries before printing, its particles are not easily stuck.

3. Precautions for gold ink printing

(1) The properties of paper

The properties of paper have a significant impact on the quality of gold ink printing. The higher the smoothness and tightness of the paper, the better the metallic effect of printing; On the contrary, printing on paper with porous surface and rough texture will result in poorer performance. In addition, the pH value on the surface of the paper should be greater than 5.5. Otherwise, when the printed materials are stacked and stored, the sulfate ions contained in the paper will cause the gold powder to discolor and turn black, and even cause the gold powder to be corroded and disappear.

(2) Gold ink printing of graphics and text

The graphics and text on the gold ink printing layout should not be too fine, otherwise it is easy to cause paste, and its reflection effect will also deteriorate.

(3) Wear resistance

The wear resistance of the gold ink layer after printing is an important indicator for measuring the quality of gold ink printing. There are currently two measures to solve the wear resistance of gold ink: one is to use a slightly higher viscosity gold ink to mix the gold ink, and the other is to use a glossy paste for polishing after printing.

(4) Gold ink discoloration

After being left for a period of time, the gold powder of gold ink printing products will be invaded by sulfur, oxygen, moisture, etc. in the air, causing the surface gloss of the imprint to darken or even turn black, affecting the quality of the product. This is what we usually refer to as the discoloration of gold ink, which should be taken into account during the storage of printed materials.

(5) Overlapping gold ink with other colored inks

Gold ink should be printed on dark colored surfaces as much as possible, such as red, blue, and black, for better results. Especially when printing gold ink on colors such as purple, black, and deep blue, the effect is even better.

Additionally, it is advisable to avoid printing regular colored ink on gold ink as much as possible. If it is necessary to print ordinary color ink on a large area of gold ink, the viscosity of the ordinary ink should be reduced first, and the printing can only be carried out after the gold ink is completely dry, otherwise it will cause the gold ink graphics and text to become blurred.