Proof calibration and color sequence arrangement/adjustment of water and ink roller pressure--problems related to improving ink color stability of printed products

1.

First, roughly adjust the ink volume of the ink fountain of each color group according to the graphic area of ​​the proof or printing plate

Secondly, according to the requirements of the production process sheet and the characteristics of the product, adjust the feeder, paper feeding, ink performance, pressure and other links in advance to avoid confusion during formal printing

In addition, according to the paper quality and graphic area of ​​the printed matter, the viscosity, fluidity and dryness of the ink should be properly adjusted in advance to improve its printability and ensure normal printing.

In short, by doing a good job of pre-adjustment before starting the machine, the failures after the official printing can be greatly reduced, and the captain will have the time and energy to focus on the ink color

2.

During the printing process, the graphic part of the printing plate must provide a continuous, uniform and appropriate amount of ink to obtain a print with consistent ink color

The equipment should be readjusted after two or three months of use, because the diameter of the ink roller will become smaller after a period of high-speed friction, especially in terms of transmission

3.
To achieve ink balance
.

As we all know, ink balance is an important content in offset printing
.
If the water is large and the ink is large, the ink is emulsified in oil-in-water, and of course the print quality will not be ideal
.

First, make sure that the pressure relationship between the water and the ink roller is properly adjusted, and that the content of fountain solution and isopropyl alcohol conforms to general standards
.
On this basis, start the machine, turn off the water supply and ink roller, and then stop to check the printing plate
.
It is better that the printing plate mouth is slightly sticky by 3mm
.
Taking the water volume at this time as the initial printing water volume can ensure the normal printing of general graphic products and basically realize the balance of ink and water
.

Secondly, flexibly adjust the water consumption according to other factors, such as the large area of ​​the printing plate graphics, the rough surface of the paper, the need to add additives to the ink, the printing speed, the air temperature and humidity,
etc.

In addition, the author also found that when the machine starts printing, the body temperature is low, but when the machine runs at high speed for one or two hours, the body temperature, especially the temperature of the rubber roller, will more than double or even higher, and the water consumption will gradually increase.
increase until the ink reaches a new equilibrium state
.

It can be seen that it is not easy to achieve the balance of ink and wash, and the operator needs to balance and use it dialectically
.
Otherwise, the ink color stability is difficult to control, and high-quality prints cannot be printed
.

4.
Calibration and color ordering of proofs
.

In production, we often encounter such a situation: the sample provided by the customer is not standard, or only one color spray draft is provided without proofing
.
At this time, it is necessary to analyze the specific situation in detail.
It is not possible to rigidly increase or decrease the amount of ink to chase the effect of the sample draft
.
Even if the proof is initially close, the stability of the ink color cannot be guaranteed, and thus the final quality of the print cannot be guaranteed
.
In this regard, the printing factory should actively exchange opinions with customers in a serious and responsible attitude, point out the problems in the sample draft and propose revision suggestions, and then make appropriate adjustments and reprints after obtaining consent
.

In production, the printing color sequence of a multi-color machine is usually determined by the viscosity of the ink
.
Because in multi-color printing, the inks are overprinted together by wet pressing, only by obtaining the best overprint rate, can prints with stable and consistent ink colors be printed
.
The arrangement of the printing color sequence must meet the characteristics and quality requirements of the printed matter, and cannot be static
.
At the same time, the viscosity of the ink can also be adjusted
.
For example, if a cover is mainly purple, and a cover is mainly sky blue, then its printing color sequence will be different
.
The former is green and then magenta, and the latter is magenta and then cyan
.
Otherwise, the overprinted color will be spotty, uneven, and unstable
.
If the printed matter is mainly black, black should be arranged in the last color group as much as possible, so that the gloss of the printed matter is better, and scratches and color mixing inside the machine are avoided
.

5.
Cultivate good operating habits and strengthen the sense of responsibility
.

Any work must have a high sense of responsibility and a strong sense of quality
.
Process operations must be standardized, and the good traditional habits of "three levels" and "three attendances" must be adhered to
.
Take diligent proofreading, for example
.
Differences in distance, angle, light source, etc.
when comparing signature samples on samples
.
It will cause visual deviation, resulting in inconsistent ink color
.
At this point, the signature sample must be removed from the sample and carefully compared
.
Long-life printing plates need to be baked to reduce the ink color difference caused by plate changing; the blankets should be cleaned frequently, and more blotting paper should be placed after each cleaning to stabilize the ink color; the five or six newly printed ink colors after Feidon are too dark , can't draw it, and the printing speed should not be greedy
.
It is very important to keep the machine stable and normal; when adding ink to the ink fountain, because the new ink is hard and has poor fluidity, it needs to be stirred several times to avoid affecting the ink volume and resulting in poor ink color
.

Operators should continue to study, carefully observe and analyze, find out the factors affecting the color change of ink from all aspects, and take corresponding measures to properly prevent and overcome them, strive to improve the stability and consistency of ink color in printed matter, and effectively improve the quality of printed matter
.