Is Gold Ink Printing Prone To Problems? Understand The Causes in 5 Minutes!

Is gold ink printing prone to problems? Understand the causes in 5 minutes!

Gold ink is ink made from gold powder, and compared to ordinary colored inks, it has a metallic color that shimmers with a golden light. This gold color gives a sense of luxury and splendor, and is often used on product packaging. It not only beautifies the product but also increases its added value. However, since the main raw material of gold ink is brass powder, chemically it is an active metal and prone to discoloration. In this article, the author starts from the composition and composition of gold ink, reviews its characteristics, and, combined with years of practical work, proposes some precautions for gold ink printing for your reference and inspiration.

01

Characteristics of Jin Mo composition

Like other inks, gold ink is composed of pigments and binders. Among them, pigments are the colorants in ink, giving the ink a certain color, while the pigments in gold ink are mainly ground metal powders, which are actually powders made from copper and zinc alloys.

The zinc content in gold powder is generally around 8%~30%. Gold ink with a zinc content between 8%~12% is reddish and is customarily called red gold; gold ink with a zinc content between 20%~30% is blue-green and generally called qingjin; and gold between red and blue gold is called qinghongjin. In gravure printing, gold ink mixing generally uses 800 mesh gold powder, and the surface of the gold powder particles is mostly coated with surfactants to ensure better bonding with the resin binder.

02

Precautions for using gold ink

Like ordinary ink, gold ink is widely printed, but due to the special nature of its pigments, there are some special precautions during storage and use.

PART.01

Because gold ink easily reacts chemically with air and water vapor and causes discoloration, it is essential to take proper storage and protection measures during use to prevent it from being exposed to air. Unused gold powder should be tightly sealed;

PART.02

Because the chemical properties of gold powder are not stable, contact with acids, bases, carbon, and sulfides can cause varying degrees of chemical changes, reducing the metal's luster and turning the gold ink black. Therefore, when using gold ink, avoid printing large-area domestic coated paper or offset paper, because paper produced by acid papermaking is acidic, and after printing, gold ink not only discolors but also loses its gloss;

PART.03

Auxiliary materials for mixing gold ink should not use acid-containing materials, but rather neutral substances;

PART.04

The use of gold ink should follow the principle of "printing as needed," meaning the batch of mixing should be suitable for continuous printing for about 3 hours, to avoid excessive adjustment causing the gold powder to remain in the oil for too long, oxidizing and deteriorating when exposed to air, and losing its golden luster;

PART.05

When printing gold ink, the printing speed should not be too fast, because if the machine speed increases, the frictional heat of the ink roller will increase accordingly, and gold ink can easily turn black due to oxidation;

PART.06

When using offset printing, the dampening solution for the gold printing should contain acids or resins to avoid the reaction between acidic dampening solution and gold powder, which could darken the ink and lose its gloss;

PART.07

When printing gold, the rubber rollers should be properly adjusted, and their positions should be adjusted accurately to prevent ink buildup caused by poor ink transfer during printing, which can cause gold powder to remain on the rollers and, after prolonged friction, lead to oxidation and discoloration of the ink.

PART.08

Semi-finished products for printing gold ink should not be stacked excessively; otherwise, the heat released by the ink during drying cannot dissipate quickly, which will cause oxidation and discoloration;

PART.09

After cleaning the machine's ink bucket and roller, the organic solvent remaining on its surface has not yet fully evaporated. If gold ink printing is performed immediately, the gold ink will react with the solvent, causing discoloration;

PART.10

If printing gold on the base color, pay attention to adding an appropriate amount of drying oil to avoid overlapping the ink due to the base ink not drying and affecting the glossy color of the gold ink;

PART.11

When printing with gold ink, the base color is generally printed first, and a light yellow or fake gold ink with strong coverage, similar to the gold ink, can be selected. When printing on coated paper or paper with good gloss, using transparent yellow ink as a base works even better. When using light yellow, transparent yellow, or fake gold ink as the base color ink, about 1% gold ink can be added to enhance the gloss of the gold ink;

PART.12

If gold printing offset printing is completed in one go, the process should be compensated during plate making. When making the yellow plate, 50% of the dots should be laid at the areas where gold is needed. If there is no yellow plate on the print, you can borrow a warm light color.

In summary, there are many causes of gold ink discoloration. As long as we correctly understand and master the characteristics and printability of gold ink during storage and use, and take effective process measures, we can not only effectively prevent discoloration but also improve the quality of gold printing, thereby increasing the added value of the product.