Correctly solve the problem of printing from the characteristics of gold and silver ink

Gold and silver ink has the characteristics of electric conduction, heat conduction, specific gravity, coarse particles, poor adhesion, etc. After friction between the ink roller and the layout friction and heat. Moisture is volatile on the plate and it is easy to produce a paste version. Should reduce the anti-adhesive off powder, dirt, scratches, anti-discoloration, anti-real gold and silver ink cover. The speed of high-speed machine printing of gold and silver ink should be controlled at 6000 sheets/hour. Adjust the appropriate printing pressure, increase the moisture content of the layout, add some gum arabic in the fountain solution, and improve the adsorption of the layout, so as not to paste the layout.

The characteristics of the gold and silver inks result in a decrease in the ink transferability, the ink is deposited on the ink roller, the roller surface is bright, and the printing plate ink is insufficient. The ink accumulates on the printing plates and blankets, making the products thin and flowery, which is not true in the field. If the viscosity and fluidity of the ink are too large or too small, the stacking ink will be produced. The viscosity of the ink will be too high and the fluidity will inevitably decrease. An appropriate amount of thin varnish may be added to the ink to enhance the fluidity. Insufficient ink viscosity, fluidity may be too high. The ink transfer rate is low, and bright paste can be added to the ink to improve the printing adaptability of the gold and silver ink.

Paper with rough printing surface and strong ink absorption, such as offset paper and whiteboard paper, is more likely to cause the surface of the printed product to rub off gold and silver powder, which is related to the nature of paper and ink. Such as the transfer of gold and silver ink viscosity is insufficient, gold and silver powder and transfer oil ratio is not appropriate, the surface of the printing ink drying speed is slow, paper absorption, printing gold oil into the paper faster, more.

If the gold and silver powder loses the adhesion and protection of the connecting material, it is easy to produce powder off. In order to prevent the ratio of powder dropping to ink, the selection of boxed ink should be cautious. Following the principle of matching the ratio of gold oil to gold powder (aluminum and silver paste), or using a brand ink with high viscosity, its fluidity will be insufficient. , can add some thin varnish. At the same time adding 1,5% -3% of red oil, in order to improve its fluidity and accelerate the drying of the ink surface of the conjunctiva.
Gold and silver inks have a strong hiding power and can be measured using a green filter of a densitometer. Density values ​​of 0.71 to 0.78 are more normal. The ink layer can be lightly pressed with a finger, and then pressed to a blank space to determine the thickness of the ink layer and the drying condition. To prevent the back of the ink from being stained on the backside or scratch the back of the printed product, the amount of dry oil should be increased, powder application should be adopted, the stacking height of the print should be reduced, and the purpose of accelerating the ink drying speed should be achieved. The product also needs sufficient parking time. The paper feeding roller should not be too heavy. When loading paper, the operator should wear cotton yarn gloves. It is very necessary to prevent finger prints and printing products from being dragged.

Gold and silver ink products are often found to be dark, dark, and dark, which is very much related to the ink, fountain solution, and paper used. Gold powder and silver powder are easily oxidized in the air. The gold-plated oil with small oxidizing property and neutral pH is preferred. The fountain solution has an inappropriate pH. Copper powder in gold and silver ink, aluminum powder chemically belongs to the active metal, chemical reaction in the case of acidic substances, destroy the color of the metal end, causing the product to change color. When printing gold and silver ink, increase the pH of the fountain solution (decrease the acidity) is generally controlled between 5.5-6.0, can add 10% alcohol. Enhance the tension of the plate surface to prevent paste plate, dirty plate and ink floating. Sprinkle the water supply system. Increase alcohol concentration. The use of minimal moisture can achieve ink balance, and at the same time it can cool the ink roller to prevent the discoloration of the printed product due to overheating.

The pH of the paper. The paper is acidic and the ink dries slowly. Gold and silver inks react with acidic substances and change color. Alkaline paper is too strong, alkaline substances spread to the fountain solution, fountain solution pH neutral or alkaline, easy paste version, water is too large, the ink is easy to emulsify, discoloration of printed products. Therefore, paper with moderate pH should be selected for printing. Generally in gold and silver ink printing color sequence, the gold and silver editions are ideally printed in the last color to prevent de-dusting. Reverse printing, scratching dirty. Due to the issue of platemaking, the content of the gold and silver version of the field imprinting has not been dealt with in a vacuum, resulting in the loss of content. This can be achieved by first printing the gold and silver version and printing the content. To make up for the defects of the plate. Gold and silver ink printing large field version, requiring the ink product layer is smooth, uniform, thick, shiny and not discolored. The correct adjustment of the printing pressure, the flatness of the liner paper, the amount of ink roller movement, and the position of the string are important considerations in printing.