Ink and printed products lose the color of gold, making the color grayish black and dull, which is a common fault in gold ink printing.
Gold ink is a printing ink made of gold powder, which is a mixed metal powder composed of copper powder and a small amount of zinc powder and aluminum powder.
The speed of the gold printing machine should not be too fast. Otherwise. The friction of ink roller increases and the heat generated increases, resulting in the oxidation and blackening of gold ink.
When offset printing gold, the contact between acid wetting solution and gold ink will have a chemical reaction, which will darken the metal luster of the printing piece. Generally, the wetting solution containing alcohol is used instead of acid wetting solution.
After cleaning the ink bucket and roller, if the organic solvents such as gasoline and kerosene are not completely volatilized, the gold ink printing will cause the gold ink to interact with the solvent and cause discoloration.
The speed of the gold printing machine should not be too fast. Otherwise. The friction of ink roller increases and the heat generated increases, resulting in the oxidation and blackening of gold ink.
When offset printing gold, the contact between acid wetting solution and gold ink will have a chemical reaction, which will darken the metal luster of the printing piece. Generally, the wetting solution containing alcohol is used instead of acid wetting solution.
Because the chemical properties of gold powder are generally not stable enough, it encounters acid and alkali. Carbonic acid gas and sulfide gas will produce different degrees of chemical changes. There are many reasons for gold ink discoloration. Solution to Discoloration of Gold Silver Ink Printing
In order to ensure the quality of gold printing products, effective measures must be taken in gold ink preservation and printing to prevent gold ink discoloration. Generally, the following problems should be paid attention to:Solution to Discoloration of Gold Silver Ink Printing
① The gold powder should not be exposed to the air during storage, otherwise it will contact with air and steam to produce chemical reaction and change color.Solution to Discoloration of Gold Silver Ink Printing
② Gold ink is printed on non coated paper. If it is affected by chemistry, sulfide in pulp and bauxite sulfate in filler in high humidity environment, the gold ink will turn black. Therefore, pay attention to controlling the environmental humidity.Solution to Discoloration of Gold Silver Ink Printing
③ Gold printing on domestic coated paper and offset paper is particularly easy to blacken. The reason is that the acid papermaking process is adopted, and the paper has a certain acidity, which will not only change the color of gold powder, but even cause the color powder to disappear.
④ Containers and rods for preparing gold ink must use porcelain. Wood products, metal products shall not be used.Solution to Discoloration of Gold Silver Ink Printing
⑤ The auxiliary materials for preparing gold ink should use neutral substances, not acidic auxiliary materials.Solution to Discoloration of Gold Silver Ink Printing
⑥ The semi-finished products of gold printing should not be stacked too much, otherwise the heat released by the gold ink during the drying process on the paper is not easy to be distributed in time, which will accelerate the oxidation and discoloration of the gold ink.Solution to Discoloration of Gold Silver Ink Printing
⑦ The cots are not adjusted well. Uneven pressure and poor measurement performance. It causes ink piling in the printing process, so that the gold powder stays on the rubber roller. After long-time friction, the gold powder is prone to oxidation and discoloration.Solution to Discoloration of Gold Silver Ink Printing
⑧ After cleaning the ink bucket and roller, if the organic solvents such as gasoline and kerosene are not completely volatilized, the gold ink printing will cause the gold ink to interact with the solvent and cause discoloration.
⑨ The speed of the gold printing machine should not be too fast. Otherwise. The friction of ink roller increases and the heat generated increases, resulting in the oxidation and blackening of gold ink.
⑩ When offset printing gold, the contact between acid wetting solution and gold ink will have a chemical reaction, which will darken the metal luster of the printing piece. Generally, the wetting solution containing alcohol is used instead of acid wetting solution.