Some situations that cause discoloration of gold ink

Gold can give people a sense of grandeur and nobleness. The metallic color of gold sparkles is also unmatched by spectral colors. Therefore, gold ink printing is widely used in packaging and printing processes to improve the image of goods to play a better role. However, since the main raw material of gold ink is brass powder, it is chemically a reactive metal and is prone to discoloration. Therefore, we should pay attention to the following situations when printing gold ink:

1 Gold ink is prone to contact with air and water vapor and cause chemical reaction to cause discoloration. Therefore, it is necessary to do a good job of storing the golden powder and avoid exposing it to the air. Unused gold powder should be tightly closed.

2 Because the chemical nature of gold powder is not stable enough, if it is in contact with acids, alkalis, carbons and sulphides, there will be different degrees of chemical changes. Reduced metallic luster, gold ink will be black. And gold ink should be avoided for printing large-area domestic coated paper, offset paper, because the paper produced by the acid papermaking process is acidic, after the printing of gold ink not only discoloration, but also loses luster;

3 The auxiliary materials for the deployment of metal inks should not use auxiliary materials containing acids, but should use neutral substances;

4 The use of gold ink should be mastered with the principle of printing with the printing, that is, a deployment of the amount should be suitable for continuous printing for about 3 hours, so as to avoid excessive adjustment so that the powder in the grease for too long time, contact with the air oxidation and lose golden luster ;


5 The speed of the gold ink printing should not be opened too fast, because the frictional heat of the ink roller is increased accordingly, which makes it easy to oxidize and darken the gold ink. Therefore, the speed of printing should be controlled at about 3000 sheets/h;

(6) The fountain solution for offset printing should use a fountain solution containing acids or gums to avoid reaction of the acidic fountain solution with gold powder, which can make the ink dark and dull.

7 When printing gold, the rubber roller should be adjusted well. The position of each roller should be adjusted accurately so as to avoid the occurrence of ink accumulation in the printing process due to bad ink transmission, so that the gold powder will remain on the roller for a long time and cause the gold ink to oxidize and discolor. ;

8 The semi-finished products of printing gold ink should not be stacked too much, otherwise the heat released by gold ink during paper drying process can not be emitted as soon as possible, and the gold ink will also be oxidized and discolored;

9 When the machine ink fountain, ink roller kerosene, and gasoline are just cleaned, the organic solvent remaining on the surface has not been completely evaporated. That is, the gold ink printing is performed immediately, so that the gold ink reacts with the solvent to cause discoloration;

10 If the gold on the background color should pay attention to properly add dry oil in the background color, so as not to overprint the gold ink due to the ink on the bottom, will affect the gold color of the ink.

In summary, there are many reasons for the discoloration of gold ink. As long as we correctly understand and master the characteristics and printability of gold ink, adopting reasonable and scientific technological measures can not only effectively prevent discoloration of gold ink, but also can better Improve the quality of printing.