(8) Perspective
1. Phenomenon : The pattern or text printed on the front can be seen on the back of the paper.
2. Reason : The paper is too transparent. Ink has soaked into the paper too deeply.
3. Solution : use opaque paper. Use quick-drying ink, and it must be thick and less permeable, and the binder used in the ink should also be less permeable. The strength of the ink should be large so that the amount of ink can be less. Add some thick varnish and some pre-drying agent to the ink.
(9) Ghosting
1. Phenomenon: The edges of printed dots are fuzzy and dirty, usually far away from the bite , showing that the dots are set on fire and pulled into tails, and the high-profile parts become cloudy, which is due to the slight movement between the paper and the printing plate caused by. Nothing to do with the bum on the printing press.
2 Reason : The paper is raised and uneven. Warped, loose paper tends to smudge. The teeth of the paper gripper are uneven. The plate is packed too tightly. Improper plate adjustment. The printing plate is loose. The edge of the paper hits the ruler. The printing plate on the machine is worn out after long-term printing, and the printing plate is misaligned. The drum is too padded. When the back of the dot is away from the grip (bite), the drum pad rides (magnetically) on the plate causing vibration. It could also be due to the effect of the drum pad, but in this case the tail of the dot is facing the nip (bite) mouth.
3. Solution : Flatten the paper. Use less ink.
(10) Printing
1. Phenomenon : The ink on the printed matter seeps from the paper surface to the bottom of the paper, and there is often a brown oily appearance around the imprint.
2. Reason: The ink is too thin and too oily. Penetrating mineral oil too much. Dries too slowly.
3. Solution: speed up the dryness of the oil explosion. Use some drying oil or better quality mineral oil in the ink. Make (or adjust) the oil to make it thicker. A small amount of silicone additives can be added to the ink.
(11) Pile of ink
1. Phenomenon: the ink is accumulated on the printing machine, the pigment is in the form of powder in a separated state, the dots are sticky, and the color seems to be inconsistent.
2. Reason : Poor dispersion of ink. Coarse particle inorganic pigments with large specific gravity are used in the ink. Ink film is too thick. The ink is diluted too much, and the link material is too thin. The rheology of the ink has dilatant properties, so it dispenses poorly. The printing pressure is not real, and the wheel field performance is bad.
3. Solution: Check the pressure, roller function and pad. The amount of ink should be appropriate. If the ink is too soft, thicker ink can be used. If there is no problem, some medium viscosity or thin varnish can be added to the ink. Replace with new oil seat.
(12) Dirt accumulation
1. Phenomenon: The fibers and coatings of the paper are accumulated on the machine, and there are dirty spots on the printed matter. Ink blotting is false and white dots are missing, especially when printing on uncoated papers.
2. Reason: The paper coating is not good. The oil is too sticky. Improper drying oil in the ink causes the ink to thicken and dry on the machine. The quality of the series is too low.
3. Solution: Wipe the machine clean and inspect it. Check whether there is skin in the oil and whether the thickness is appropriate. Check whether the dryness of the oil on the machine and on the paper is suitable. If the ink is too thick and dries too quickly, it can be diluted with dilute ink, pan additive or paste thinner.
(13) The color is floating or inconsistent
1. Phenomenon: There are differences in the color of the printed matter at different positions on the same paper or at different positions on different papers.
2. Reason: The ink used is not consistent in terms of color, pigment content, consistency, brightness, and copper luster. In the same batch of ink, due to chemical reaction or flocculation of some pigments during storage. Paper discoloration in storage, inconsistent surface, inconsistent absorbency, and more. Inconsistent light conditions when mixing colors in a printing room. Due to the inconsistent roughness of the paper surface, the amount of ink given by the printer is inconsistent in order to make the printed matter realistic. Changes in temperature and humidity during the printing and drying process will cause changes in the ink penetration ratio, resulting in differences in gloss and color between printed products. Inconsistent due to dryness. Too much thinner added. For example, the quality of printing plates is inconsistent, resulting in unbalanced addition and subtraction of colors.
3. Solution: Check the customer's color standard and the amount of ink on the printed matter. Inks should be kept in good condition. Printing presses need to run under consistent and satisfactory conditions. The quality, surface properties and color tone of the paper should be strictly checked. Color comparisons should be done in good daylight conditions, never in dark corners or under different artificial lighting, and better yet, be a human judge. Whether the drying speed of the ink is consistent with the standard. The flocculated oil should be redispersed and checked for normal fluidity. If the ink has deteriorated, it should be replaced with new ink.
(14) Phantom (Shadow)
1. Phenomenon : The image appears vaguely and repeatedly in places where it should not appear. Generally speaking, this phenomenon is easy to occur when printing the field and dots with a flatbed machine.
2. Reason: when the plate moves up, and when the plate wheel is pressed down, the ink moves on the plate again. The ink does not have a chance to redistribute before going up, so the outline of the plate (figure) on the silver is replicated on another part of the plate.
3. Solution : The strength of the roller should be appropriate. A steel riding roller can also be used, but it must be installed correctly. When printing solids and dots, the rolling range of the roller should be shortened. Check that the wheel is adjusted correctly and is the correct size, or if a lighter roller is used.
(15) spots
1. Phenomenon : Spots are stains of different shades of solid prints. This disadvantage is more likely to occur when printing on the spot with a flatbed flatbed machine, among which green and brown are the most troublesome colors. .
2. Reason : The ink film is too thick, the transfer is not suitable, and the printing on the paper is uneven and squeezed. The ink film is too thin and does not completely cover the paper surface. The ink is too viscous, resulting in poor splitting of the ink film upon imprinting. The cracked ink filaments cannot be well leveled on the paper and become beads (commonly known as fish scales in my country). The imperfection of the paper surface is an important factor, if there are hard spots on the paper, it will absorb ink very easily and the result will be blotchy. Poor coating on the paper, uneven moisture absorption of the paper. Printing pressure is too heavy. Insufficient pressure between the rollers on the press, eg too few rollers, resulting in poor ink distribution. The surface of the printing roller is too hard, causing slippage and excess ink in places. The oiliness of the ink is too large, the ink is too thin, too long, or the ink is diluted too softly. There is too little pigment in the ink. The color is too weak (light). Cover (overlay) printing is more likely to produce spots than single color, especially when the bottom color has been crystallized, it is not easy to print fullness of overprint color or have a flat feeling on the first color.
3. Solution : switch to printing with a flat press or a round press printing machine. Use a resilient backing for cardboard or stiffer paper. Use more ink distribution rollers. The printing pressure should not be too heavy. Minimize the design of the field and use the pattern of dots. Paper and ink should adapt to each other. Paper with a hard surface should use thick and viscous ink, which can reduce the disadvantages of extrusion. If it is caused by too thick imprint, you can use soft ink with strong coloring power, so that it can be printed thinly. If the imprint is too thin, you can mix some colorless lightening agent into the ink to make the ink thicker. If the coloring power of the ink is too high and you use opaque white ink to lighten it, it may cause Coverage of paper is not perfect. If the ink is too thin, add some medium viscosity varnish or oleoresin varnish, or add some thick lightening agent, etc. If it is too oily, add some carbonic acid cake and redisperse it with a tricycle, or add corresponding pigments. The ink should be made opaque, and the transparent filler should be replaced by titanium powder. For printing inks, pigments with similar specific gravity and oil absorption should be selected to avoid mixing pigments with large differences in specific gravity. If flat ink is used, the spots are bright and glossy, which is caused by the impermeability of the ink in these parts, and the ink that cannot form a continuous film at the end can be selected. On the contrary, you can choose a highly glossy ink. If it is a process printing, the second color should be printed immediately after the first color is dry.
