Source: Fine Art Network
1. Characteristics of metal
Gold ink has a very strong hiding power. It not only prevents the visible light from passing through, but also blocks the transmission of ultraviolet rays and infrared rays. However, the chemical resistance of Jinmo is not strong. When it encounters acids, alkalis, water, carbonic acid and other gases, it will produce chemical reactions and reduce the metallic luster. Therefore, to maintain the gloss of printed gold products, it is necessary to prevent the erosion of air, water vapor and sulfides.
2. Effect of fountain solution on gold luster
When printing gold, it is best to use alcohol and chromium salts fountain solution, should not use the white syrup, because it contains a strong oxidizer nitrate, black ink will make gold.
In addition, the amount of water should be as small as possible, because gold ink is afraid of water, easily emulsified and affect the luster.
Gold ink is still afraid of acid, so the fountain solution PH value is best controlled at `5-6 is appropriate, acidic too strong, gold ink is easy to darken.
3. The impact of paper on the luster of gold ink The printing of ink on the bottom is very important. For example, the low quality of the copper plate, the high quality steel paper is smooth and dense, and the printed gold on the printed background may not be printed with ink. The low-quality steel paper is soft and papery, so it should be printed with a layer of ink at the end to make the pores saturated. It should be flatter and brighter than printing directly on paper.
When gold is printed on whiteboard paper and offset paper, since these papers are looser and more absorbent than steel plates, it is necessary to print a layer of ink at the end. It is best to use organic transparent yellow as the gold background color, because the transparent yellow has good transparency, fine particles, good reflection, and has the characteristics of acid resistance, durable alkali, and gas resistance.
The ink at the end of the printing should be properly dried with some red oil to facilitate the drying of the bottom ink within 4 hours. The golden ink should be superimposed on the dry ink. If the bottom ink is overprinted, the gold ink will be overprinted. The gold ink will be absorbed by the bottom ink, which will affect the metallic luster.
Large prints can be printed twice to achieve fullness. In order to infiltrate the gold ink well, it is best to superimpose it in a semi-dry state. If necessary, it is also possible to imprint with the original printing plate once, so that floating gold phenomenon can be avoided.
4. Other considerations
(1) When designing, it should be noted that the printed gold and silver artwork should not be too thin, and should be printed on a dark background as much as possible. For example, printing gold on ink or red can have a significant effect; if it is printed on yellow or other light colors Gold, the effect will be worse.
(2) The use of ordinary ink can be used for continuous printing, but the printing of gold is different, because the metal is not rubbed and rubbed, after the ink roller rubs for several hours, the gold ink luster will gradually become dark. Therefore, it must be cleaned, replaced with gold ink, and then printed so that the brightness of the gold ink can be increased.
(3) When printing gold, the dry oil of the previous set should not be placed more, so that the phenomenon of overprinting can be avoided. In addition, do not add dry white oil, because the white dry oil contains lead compounds, chemical reactions will occur with the gold ink, affect the gold ink hue. If the gold ink dries too quickly, add a small amount of phthalic acid, dibutyl ester, etc., to reduce the drying rate.
(4) The pressure setting between the printing ink rollers is adjusted to be slightly smaller to ensure that the printing ink is not pasted or dirty. However, the pressure between the impression cylinder and the rubber tube can be appropriately increased, which is conducive to the smooth transfer of gold ink to the substrate.
(5) The flow of gold ink should be appropriate, and at the same time, it should be based on the nature of the paper, layout and graphic conditions, machine speed, and other flexibility. When using offset paper and whiteboard paper, dilute one point; use steel paper to thicken one point; large-area field version must be thinned; when the speed of the machine is slow, it should be thinned.
(6) Gold ink should be used now, otherwise it will be oxidized and darkened for a long time.
(7) The speed of the machine should not be too fast, too fast is not conducive to the smooth transfer of gold ink, and will increase the friction between the gold ink in the ink roller, affecting the brightness of the gold ink.
(8) In order to protect the surface of printed gold, post-printing processes such as laminating and laminating may be adopted.
In short, according to the characteristics of gold ink, in the process of operation to take appropriate effective measures in order to print a good print.
How to get a good impression of gold
The metal is characterized by its bright color and bright colors. Therefore, in some packaging prints, cover the part of the pattern printed in gold, can be more beautiful and gorgeous. The quality standard for printing gold is bright color, strong metal feeling, smooth and smooth graphics, no discoloration and no fading for a long time. How to get a good impression of gold is worth exploring.