Printing Knowledge

The thickness of the ink film on the rollers is a very important consideration in printing. Typical ink film thickness on a lithographic press is 0.2~0.4 mils (0.0002~0.0004 in., or 0.005~0.010 mm), depending on the ink color and printing sequence. The press operator should control the amount of ink being carried by the inking system for more preci…

The primary function of solution is to desensitize the nonimage areas of the printing plate to ink. A surface that is "desensitized to ink" is a surface that ink will not adhere to. An area sensitized to ink will accept ink readily. The dampening solution also helps to keep the plate, rollers, and blanket cool and washes away much of the dirt and d…

Dampening solutions are usually sold as concentrated solutions that are diluted with water to the proper concentration. In concentrated from, it is commonly referred to as fountain concentrate, fountain etch, or just etch. Most one-step concentrates already contain a natural or synthetic gum, an alcohol substitute, and other essential ingredients, …

Densitometry, colorimetry, and spectrophotometry are the three methods used to measure color in the graphic arts. The densitometer measures optical density. It is essentially colorblind, measuring only the level of reflectance of the transmittance of a film. Density varies with ink film thickness, but data can also be used to determine dot area. Co…

Solid ink film measurement. To maintain image quality during the pressrun, the operator is concerned with the ink film thickness being printed on the paper. When ink films are too thin, the images will appear to be washed out. When ink films are printed too thickly, many problems can result including poor drying, halftone plugging, and scumming or …

All web-fed gravure presses start from an unwinder, which serves the purpose of unwinding a roll of substrate, deeping, keeping adequate tension on the web. The printing unit, figure 4-1, the heart of the gravure press, consists of the following components, regardless of the application: . The image carrier, a cylinder engraved with the image to be…

Every gravure press is a custom-buit machine, designed and engineered for a specific range of products. A packaging press producing 26-inch-wide labels is identical in principle to a floor covering press printing 15--foot-wide vinyl floor coverings. The wide range of sizes and substrates, as well as the variety of in-line converting make each gravu…

Publication presses are designed for high speed printing high quality color publications. Typical products include magazine, Sunday newspaper magazines, catalogs, newspaper inserts, and advertising printing. The product requirements of publication gravure are: • Multiple printed sheets must be folded and assembled into complete publications on the…

Gravure packaging and product presses are divided into two distinct groups for light weight versus heavy weight substrates. Typical products for light weight substrates include but are not limited to flexible packaging, gift wraps, paper and foil labels, and decorative films, lleavy weight substrates include folding cartons, floor coverings, vinyl …

Sheetfed Gravure.  Although almost all gravure production is on web presses, sheetfed gravure presses still exist. Sheetfed gravure is used for proofing; for printing jobs which must be printed on paper available only as sheet; for fine art reproduction and posters; for extremely high quality cosmetics cartons; and overall coating of a product tha…

Signatures. A complete sheet containing all the artwork for a cylinder is called a signature. By examining or taking apart a magazine or book, it is often possible to see how it was assembled from individual signatures. A folded signature, depending upon cutting and slitting, can come from the folder with tow sides open or three sides open. Ribbons…

The U.S. population of gravure presses has undergone substantial expansion and rebuilding in recent years. Nonetheless, there are still many different folder configurations in use. The following section describes the types of folders used in the industry, and how the folding is processed in the upper and lower folder sections.
• Former Board Newsp…

In the stack press (Figure 4-6), individual color stations (sometimes called sections or decks) are stacked one over the both sides of a main press frame. Each color station is driven through gear trains supported by the main press frame. Stack presses are made with one to eight color stations, although the most common configureation is a six-color…

The central impression press, sometimes called a drum, common impression or CI press, supports all of its color stations around a single steel impression cylinder mounted in the main press frame, Figure 4-7. The impression cylinder supports the web, which is thereby "locked" to the cylinder as it passes all color stations. This configuration helps …

The in-line press is the third commonly used type of wide-web press. Its color stations are separate, complete units horizontally mounted one to the other, and may be driven by a common line-shaft. In-line presses can be manufactured with any number of colors. This type of press can be easily designed to handle varius web widths, from narrow to ext…

Folding cartons have been printed by flexo for many years, but it has only been in the past 10 years that the industry has started using state-of-the-art central impression presses for this application. Pizza cartons illustrate the type of work that was originally relegated to the flexo process. The ability to print multi-colors in close register o…

Narrow-web flexo has most recently been defined as any web width less than 20" (508mm). While this is an arbitrary designation, it will serve as a definition for this chapter. The vast majority of narrow-web presses, however, are 16" (406mm) or less, and most are 10" (254mm) or smaller, However, changing market conditions and the need for greater p…

The origin of narrow-web flexography is usually placed in the period immediately after WW ll. At that time, Mark andrews Sr. (1904~1980), the founder of Mark Andy, Inc., made his first presses for printing on the then new product, "scotch Tape." Others may have made similar equipment prior to this but, unquestionably, Andrews was the first to begin…

Many types materials can be printed. Plastic, glass and fabric are just some. However, by far the most important printed material is paper. Paper is needed for letterheads, envelopes, invoices, checks, travel brochures, calendars, advertising pieces and catalogs. And, of course, paper is an essential ingredient in newspapers, books, and magazines. …

Making paper by hand is an excellent way to become familiar with the basic procedures of papermaking. Extensive equipment and materials are not required. Equipment includes a tub large pail, a mold, and a deckle. These three items are shown in Figure 5-1. The mold is a wooden frame covered with a metal screen. The deckle is another frame the same s…