A stencil is the equivalent of a mold for an image, as a way to reproduce it identically without having to draw or paint it endlessly – a principle also common to a printing system. In this case, the image becomes the matrix. In the context of screen printing, this stencil refers to the screen itself, right after the entire process of waterproofing the mesh along with the opening of the matrix, and which, by the nature of its constitution, is defined as a permeographic stencil.
Generally, there are three ways of producing a silkscreen permeographic stencil, between indirect and direct methods: 1. by collage – cutout (indirect) 2. by UV exposure – photosensitization (indirect) 3. by direct painting – touch-and-glue type (direct)
The silkscreen stencil by cut constitutes the oldest method and continues to be used in educational and/or occupational screen printing – using paper. The image is transformed into a traditional paper stencil, which, when applied to the screen, transforms it into a permeographic stencil. A thin, non-absorbent paper that is easy to cut manually is suitable (e.g., engineering paper), which is then glued to the screen on the substrate side. This gluing can even be done with the printing ink itself, allowing it to dry before starting to print. In addition to paper, other options exist that enable a professional screen printing practice. Among professional cutting options, there are also specific types of film on the market for manual cutting and intended for screen printing stencils (modern evolutions of old patents , including different solutions for water-based and solvent-based inks, with improved options for more eco-friendly manufacturing. The advantages of these films are related to the ease of manual cutting and the much greater resistance of the stencil during printing, compared to other options. However, more accessible, practical, and economical alternatives have emerged on the market and become widely popular, such as the use of self-adhesive decorative vinyl. This material is manufactured for both manual and mechanical cutting, ultimately becoming a benchmark method, despite being much less resistant and durable. Its simple process, without chemicals, with reduced water consumption involved in removal, easy acquisition, and possible recycling of the vinyl are the reasons for its popularity.
The stencil by screen exposure is one in which the matrix is fixed to the screen by a chemical process – photosensitization -, the only screen printing stencil method compatible with all types of substrates, all types of inks and degrees of image detail, transversal to all levels of screen printing practice, and which can also be called a photostencil. This is the type that has undergone the most evolution over more than a century, among a myriad of inventions, until reaching the simplicity of current processes. In this case, the matrix is produced separately, in film material, to be placed on the screen only after it has been covered with a sensitized screen printing emulsion. By exposing the emulsified screen to a light source rich in ultraviolet radiation, a chemical reaction will occur that will somehow transport the image from the film sheet to the screen. This stenciling process can be referred to in several ways, with the term “development” in reference to its origin in photographic development. From the point of view of sensitization, the process is further divided into three types – indirect, direct and mixed.
Direct silkscreen stencils are another process inspired by the past, originating from the first screen printing patent, in which the production and opening of the stencil are carried out simultaneously with the waterproofing of the screen, manually and directly, by hand painting and applying glues or filling liquids. This type of stencil is distinguished by two methods – positive and negative. The direct silkscreen stencil methods are still applied in artistic circles, mainly due to the freedom of experimentation, providing another space for creativity, varied techniques of effects and textures. It is also a type of stencil with reasonable durability, far superior to a cut-out stencil, so, considering the context of limited editions so characteristic of the art sector, it remains a very well-suited option for the artist’s objective.
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