Experience in the preparation and use of fountain

Experience in the preparation and use of fountain solution in offset printing

offset printing is inseparable from water, and the conversion rate is required to be low (fountain solution). Fountain solution must be prepared reasonably according to different use conditions, and the amount of fountain solution should also be different according to the weather conditions, the type and color of ink, the actual area of printing plate and other specific conditions. At the same time, we should also consider whether it is visual printing, whether it is the first color printing, whether it is superimposed color printing and other factors. The following fixtures equipped with the van rider (1) machine should be coated with anti rust oil for storage; Take wetting powder and clear water as an example to discuss the preparation and use of fountain solution

1. when preparing fountain solution, according to the ink depth, the amount of fountain powder is arranged in color order, generally magenta, black, cyan and yellow. Take 10L plastic barrel as an example, add 3 small spoons of fountain powder to the fountain solution barrel for black version. When preparing the fountain solution for other color sequences, the amount of fountain powder can be increased or decreased accordingly

2. With the increase of ink layer thickness, the amount of fountain powder increases. That is, for printing pieces with large ink consumption, in order to prevent the blank part from getting dirty, the amount of fountain powder must be increased when preparing, rather than simply increasing the amount of fountain solution. At this time, we can observe the moisture in the layout on the side of the machine, and it is better to have a slightly shiny layout without floating water. If the paper of the printing product curls, turns up, or there are water drops dripping along the rubber, and there are water drops in the ink roller and ink bucket, these are the reactions of water, which should be corrected in time

3. adjust the dosage of fountain powder according to the dosage of dry oil. The dosage of dry oil increases, and the dosage ratio in fountain solution increases accordingly

4. adjust the amount of fountain solution according to the workshop temperature. For example, before and after lunch, the water consumption should be appropriately increased by 1 ~ 2 grids, otherwise, due to the small number of personnel on the machine, the adjustment times will be reduced, and the evaporation of the fountain solution will increase, which is easy to make the prints dirty

5. Adjust the amount of fountain solution according to the nature of the paper. When printing paper with loose texture and many impurities, due to the high viscosity of the ink, the paper is easy to fuzz, and the impurities accumulate on the several precautions put forward by the rubber blanket for the hardness tester of Jinan experimental machine factory. Increasing the wear of the printing plate is easy to get dirty. At this time, the supply of fountain solution should be increased. If you print a book with paper, you should increase the supply of fountain solution. In addition, paper prone to static electricity can be fed smoothly by increasing the water supply

6. adjust the amount of fountain solution according to the graphic situation of the layout. The layout is generally composed of fields, lines and dots. If the full page is a printing plate with field anti white words or lines, the amount of fountain powder can be increased appropriately. For printing plates with all dot level images, the amount of fountain powder should be reduced. Both on-site and on-site printing plates should be taken into account

example: for the printing layout, if the ink volume is adjusted uniformly, after the water volume is determined, the printed products usually have a slightly lighter ink volume and water spots at B and E. At this time, even if the amount of ink is not large, it will cause dirt on the back. At this time, the local water supply must be controlled. The simple method is to stick a paper strip with corresponding width on the receiving roller to prevent or partially reduce the water supply to B and E, so as to saturate the local ink color. So how to carry out local control

find two bricks and process them to grow about 3 ~ 8cm (consistent with the contact with the water roller). Tightly wrap them with flannelette and sew them. Put it in the bucket and tangent to the water roll, which can be used to control the local water supply. The size and position of bricks can be determined according to the situation of points B and E

in addition, the common "paste" failures in printing are not necessarily caused by the fountain solution. You may not have heard of polylactic acid paste in most cases, such as excessive ink volume, high ink fluidity, too much dry oil, too strong ink polarity, too fine sand holes in the layout, and too much printing pressure. Therefore, when a paste occurs, you should first analyze the cause and determine that it is the problem of fountain solution, and then increase or decrease the water supply or the dosage of fountain powder as appropriate

reprinted from: Northeast printing