Serigraphy [screen printing]

Serigraphy or screen printing is a permeographic printing technique that today uses a polyester fabric, steel fabric or nylon fabric stretched over an aluminum, painted metal or wood frame called a “screen printing frame” or “screen printing frame” as a matrix. The fabric used is also called “screen printing fabric” or “screen printing fabric”. The term “serigraphy” comes from the Latin “sericum” (“silk”) and the Greek “γράφειν” (“gràphein”, “to write”). The earliest fabrics that served as a medium for screen printing were silk.

Screen printing is a printmaking process where ink is forced through a mesh screen onto a surface. Making certain areas of the screen impervious to printing ink creates a stencil, which blocks the printing ink from passing through the screen. Ink is simply pushed through the stencil against the surface of the paper, most often with the aid of a squeegee. Generally, the technique uses a natural or synthetic ‘mesh’ fabric stretched tightly across a rectangular ‘frame,’ much like a stretched canvas. The fabric can be silk, nylon monofilament, multifilament polyester, or even stainless steel.

The essential tools required are a squeegee, a mesh fabric, a frame, and a stencil. Unlike many other printmaking processes, a printing press is not required, as screen printing is essentially stencil printing. Screen printing may be adapted to printing on a variety of materials, from paper, cloth, and canvas to rubber, glass, and metal. Artists have used the technique to print on bottles, on slabs of granite, directly onto walls, and to reproduce images on textiles which would distort under pressure from printing presses.

See also: Screenprint process explained by The Metropolitan Museum of Art, New York

Permeography is based on a process of sealing off defined areas of the printing fabric to allow an ink placed on top of the printing fabric to permeate through the open fabric and onto the surface below the screen printing screen. The passage or permeation of ink from the upper part of the screen printing screen to the printing surface below, through the screen printing mesh, is achieved by passing, with a slight pressure, a bar with a polyurethane elastomer edge that rests on the ink and presses it through the printing mesh by a sliding movement. This bar is called a squeezer or squeegee for screen printing.

This printing action can be repeated in a cyclic way, by hand or by means of special screen printing machines, reaching a high production speed, able to satisfy according to the equipment available for the craftsman or the industry.

The process of waterproofing the fabric of screen-printing heald frames is nowadays obtained by means of special water-based photoemulsions that are applied uniformly on the fabric stretched on the screen and then dried, forming a cohesive but water-soluble film. If these coated screen-printed screens are exposed to light – and more precisely to ultraviolet light with a wavelength of around 365 nm – they undergo hardening in the exposed areas, losing their water-soluble property. If one exposes to ultraviolet light a screen printing picture with a photographic film (with black areas, in correspondence of the graphics, and with areas transparent to the light in the other parts) over the coated fabric, where it receives light, the photoemulsion hardens, while where the film is black the photoemulsion, not receiving light, remains water-soluble.

In practice, after the photoengraving process through a simple washing with water you have a development of the screen printing frame that will reveal the areas of free fabric, in correspondence of the black parts of the photographic film. To date, screen printing is an established industrial printing technology, widely used in all applications where a higher ink deposit is required compared to other printing technologies available today, such as offset printing, flexographic printing, inkjet printing.

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