Letterpress is one of the typical methods for applying information using a relief matrix. Elements that protrude are coated with paste-like paint and then pressed onto paper. Thus, various mass periodicals, reference books, books and newspapers are replicated.
Technology development
Previously, the forms were in the form of smooth plates on which drawings and words were carved. This printing method is called woodcut. It is sometimes used in our time, if it is necessary to create artistic reproductions. The invention of typesetting printing plates led to the development of typography. Each page was made up of individual characters and letters. Character elements were cast from lead or carved from wood. Then letterpress machines appeared, where the text was typed much faster. The protruding letters were rolled with paint, and under the press they made an imprint on paper.
One of the last stages of development was the use of printing plates from photopolymers. There are plates based on aluminum - for flat printing, film - rotational.
Current metal molds are made by methods:
- milling;
- etching;
- engraving (cliche, stamps).
Their use is limited. This is because the composition contains lead, a metal that is rather harmful to health. Similar forms are used for:
- creating a picture of genuine leather;
- relief stamping;
- foiling.
One of the famous varieties of letterpress is flexography. This letterpress method uses flexible forms made of photopolymers with a small 0.5-0.7 mm deepening of the blank elements. The impression with this method is obtained using a cylinder, a polymer matrix is fixed on its surface. As a result, the pattern is continuous with repeating parts of the pattern. The width of the paper and the diameter of the cylinder determine what it will be:
- wallpaper;
- packaging;
- labels.
Specificity of prints
High resolution printing is performed on:
- paper;
- foil;
- self-adhesive film;
- polyethylene;
- vinyl;
- cardboard, including corrugated.
Bright pictures consist of tiny square or round prints. 4 colors are used in color printing . A raster rosette is visible on these images - a distinct structural pattern.
If you look at the photo of letterpress printing, you can understand that the use of technology in printing does not go beyond the resolution of printing. The limit for this method is the publishing of newspaper and book text, as well as single and colorful illustrations. If you study prints on printed surfaces through a magnifying glass, you can see thickenings of paint along the contour of the elements. Due to this, raster images acquire color saturation, and symbols and letters have a sharp outline. Notches in chopped fonts and thin strokes are smooth and continuous.
Such printing (letterpress printing) suggests that pressure is needed to transfer ink to paper. As a result, a convex outline is formed on the back side of the sealed base, which is noticeable, and it can also be felt with your hands. A fresh print smells like kerosene, because the binder components of printing inks are made from petroleum refining products.
Advantages and disadvantages of letterpress printing
Letterpress technology stands out for its simplicity, which is one of the pluses. Other benefits include:
- stable image quality;
- reliable technology;
- independence from humidity of the printed substrate;
- legibility and clarity of the mark on the prints;
- low cost of production;
- low cost of equipment.
The positive aspects of letterpress include the fact that you can use water-soluble, alcohol and oil paints.
Despite the fact that the photo for high resolution printing looks as perfect as possible, this technology has certain drawbacks, one of them is the low resolution of the equipment. A convex relief is formed on the print on the back side. The downside is low performance, in other words, low speed. Printing this type of permit is advisable from an economic point of view to use in the production of books and newspapers. It is noted that in order to cast a flexible photopolymer matrix, you need to spend 1-2 hours, and metal cliches will have to be made more than one day, since such a process is painstaking and costly.
Scope of Letterpress
Letterpress is a type of printing in which print elements are positioned higher than white space. They are not used in advertising. She continues to print newspapers, manuals, labels, leaflets and forms in printing houses with outdated equipment.
Today, flexo printing, where a flexible printing form is used, is more common. It is used in the production of:
- stickers and stickers;
- labels for food and industrial products, cardboard tags;
- tickets with transverse perforation and numbering;
- candy wrappers;
- disposable tableware;
- labels for clothes;
- plastic and paper bags;
- flexible packaging for food, drinks and so on.
Types of equipment for letterpress
A high printing method involves the use of different types of equipment, one of which is a crucible printing machine. In it, the form is mounted on an immovable flat surface on which printing rollers roll ink. Next comes the paper and is pressed to the form.
In a rotary printing machine, the printing mold is not flat. It is located on a plate cylinder, which during the process is in contact with the second cylinder. It is another cylinder that paints the mold. In this case, the printing speed can be increased.
In a flatbed machine, the mold moves back and forth, coming in contact with the printing cylinder.
Servo Drives
A servo-drive machine is an automated device with electronic control. This model is considered very productive and productive, all thanks to improved print quality and a minimum of waste. Such machines stand out for optimal independent control of each printing unit. They have an intuitive touch screen, as well as a winding and unwinding device that allows you to adjust the tension. From the central control panel of the servo-drive machine, as well as locally, you can quickly change the printing forms.
Servo Rotary Machines
The HTC 260/460 rotary servo drive allows you to use at most 12 colors. Such multi-color characterization of letterpress and flexography. The device can be understaffed with circular rotation stencils. The main printing media are laminates and self-adhesive paper. This machine is designed for the production of blanks for laminate tubes and bendable packaging. The main features of HTC 260/460 are:
- almost complete wastelessness;
- retrofitting cold stamping with foil;
- admissibility of lamination.
All role-playing equipment, where printing images are printed from roll to roll, will be an excellent solution for the production of a huge circulation of label and packaging products. High performance of rotary machines is explained by the use of rolls.
The difference between offset and letterpress
Printing clients who are not tech savvy often confuse these two types of printing. Offset printing technology does not provide for the presence of protruding parts on the surface. Transfer of ink to paper occurs through an offset cylinder, which is an intermediate element. During printing, these elements moisturize. For the manufacture of print marks and spaces, materials that differ in physical properties are used.
In letterpress printing, printing marks rise above the white space. The printing process takes place under strong mold pressure on the paper. A printed matrix is made of one material. In the process, it does not need to be moistened.
The common feature of these two types of printing is that they decorate three-dimensional objects. The imprint on the paper is transferred by a convex matrix, an offset cylinder is used.
Conclusion
Letterpress is the beginning of all printing technology. Today it is constantly being improved.
This technology uses a viscous paint that does not spread out in shape, which means that white elements do not need to be cleaned. As a result, printing plates become more convenient to use. Although flexography and offset are modern variations of letterpress printing, the latter is still used to create newspapers and books.