Types of printing forms

We deal with items that the printing process has been used to create on a daily basis. Virtually every product we own or see in a store, as well as some of the infrastructure of our entire lives, must have been covered with ink or some other type of material used in printing. The way in which an item is printed is determined by what are called printing forms. How many are there? What kind of forms are they? And what are their characteristics?

If we look around, we will surely notice a lot of objects, whose final shape was determined by the type of printing placed on it. A favourite T-shirt, a colouring book of our child, a stamp on an envelope received from the letter carrier – all these are the result of using one of the printing methods, and thus also of the printing forms.

A printing form is nothing more than a part of a printing device that accepts ink or another substance in order to be reflected on another surface (the so-called printing substrate). A printing substrate in this case would be the mentioned T-shirt, a blank page of a colouring book or an envelope.

It is worth remembering that every printing form will have so-called printing and non-printing areas within it. The printing areas – as you can guess – are the surfaces that will take the ink and then give it back to the surface we want to print on. Non-printing areas, on the other hand, will not accept ink so that it will not be reflected on the printed surface. An example of printing place can be the outline of the colouring book, and non-printing place – its center and background, which will be filled not by the printer but by the child.

What types of printing plates are there?

Currently there are three types of printing plates used in modern printing. We are talking about flat, convex and concave forms.

Flat forms are used mainly in light printing, offset and lithography. They are characterized by the equality of printing and non-printing surfaces. Therefore, we will have to deal here with the need to distinguish them from each other in a way other than their physical shape. It is worth knowing that in the case of lithography – the printing form is a lithographic stone, while in the case of offset a special cylinder covered with rubber is used.

Convex forms, which are characteristic for such techniques as rotogravure or pad printing, as opposed to flat forms – will already take advantage of the differences in the physical shape between printing and non-printing areas. As the name of the form suggests, the printing areas here will be convex, i.e. those that “protrude” above the surface of the form. Convex forms are best illustrated by imagining how a stamp works. We apply it to paint or ink, which is deposited on its convex elements, in order to reflect the established symbol on paper. The print will therefore in effect take the shape of the convex printing areas.

Concave forms – like convexforms – will also rely on the surface irregularities of the printing and non-printing areas. However, in their case it will work the other way round. The concave areas will be the printing areas and the convex areas the non-printing areas. The operation of gravure molds is fairly simple and quick. Initially, ink is applied to the entire mold to be collected from the non-printing areas and left in the printing areas. This way, when the mold is applied to the printing surface (printed substrate), the ink from the concave areas will be reflected on it.

Photo: Material from customer