1.Ordinary paper

Before printing, it is necessary to measure the exact thickness of the paper with a micrometer, and then input the corresponding value in the offset press console, and then fine-tune the pressure of each printing color group according to the actual ink color of the printed product. If the paper thickness is judged only by experience without measurement, there will be incorrect setting of printing pressure. The printing pressure is too large, it is easy to make the rubber blanket lose its due elasticity, shorten the service life of the rubber blanket, and there will be problems such as inaccurate overprinting, dot deformation, and inaccurate color restoration. The printing pressure is too small, it is easy to produce a large area of field printing is untrue.

2.Locate the paper

Some cigarette pack products, the paper used has been designed in the early stage of the pattern, in the printing production, the offset press must be registered on these patterns. Due to the limitations of the early production process, the position of these patterns is likely to be different, which puts high requirements on printing production. The correct way is to classify the paper according to the rules before loading the paper, select the paper with the same rules to print first, and adjust the front and side rules of the paper with different rules before printing, so as to effectively reduce the bad prints caused by frequent adjustment of the rules.

3.Ink

In order to eliminate the problem of a large amount of spot color ink waste caused by product production, the spot color ink of many products is prepared with the original ink before the machine. Therefore, in the offset printing spot color ink proof, it is necessary to accurately record the composition and ratio of each spot color ink, before mass production, ink mixing personnel to determine the correct ratio of spot color ink, and estimate the amount of ink, to avoid repeated deployment caused by color difference, waste ink and other situations.

4. Additives

The use of additives must be careful, such as desviscosifier, ink oil, etc., should be added appropriately, generally not more than 5%, mainly to increase ink fluidity. If excessive addition, it will make the ink in the offset printing process wire drawing, floating dirty, flying ink, crosstalk and other problems.

5. Moisturizing solution

The correct pH value of the moistening solution is a necessary condition for the blank part of the plate to generate hydrophilic inorganic salts and keep clean, so the pH value of the moistening solution must be strictly controlled. General version of the pH value of 4.8 ~ 5.5, the other data are: temperature 10 ~ 12℃, electrical conductivity 800 ~ 1200μs/cm, alcohol concentration 12% ~ 15%, and must be regularly measured and confirm the version of the pH value and other data in the standard range.

The main component of the moistening solution is water, the quality of water directly determines the quality of the moistening solution, but the current water quality in the northern region is hard, the content of calcium and magnesium ions is high, which calcium and the resin in the ink contact easily form saponified calcium, and when combined with the acid in the acid moistening solution, it will produce salt such as lemon calcium or calcium phosphate, which is easy to make the surface of the water roller and the ink roller produce crystallization. Resulting in poor water and ink transfer. Therefore, when the calcium accumulation on the surface of the offset press water roller and ink roller, it should be cleaned in time, otherwise the surface of the rubber roller is easy to produce sand holes due to wear, resulting in uncontrollable ink balance. At the same time, the moistening solution should be replaced in time after about a week of use, and of course, it is best to use softening water under conditions.

6. Blanket lining

The thickness of each printing color group rubber blanket lining must be consistent, otherwise it will affect the overprinting accuracy of the product, especially when printing some products with high overprinting accuracy requirements. However, even if the quality of the package is relatively good, it is inevitable that there will be inconsistent thickness, so before using the package, it is best to use a micrometer to measure the thickness of the package, and then use it after confirming the consistency.

In addition to ensuring that the thickness of each printing color group rubber blanket lining is consistent, it should also choose a smooth surface and good compression resistance, which is conducive to the improvement of printing quality.