Screen Printing

Screen printing is a commercial and industrial technique which involves the passage of a printing medium, such as ink, through a taut fabric to which a refined form of stencil has been applied. The stencil openings determine the form and dimensions of the imprint thus produced. The overspread uses silk or other fabric stretched tightly over a frame. The images are created by blocking parts of the screen with stencils created by hand-drawn or photographic techniques. The ink is forced through the open areas of the screen onto paper or fabric.

Screen printing is a printing form which is weatherproof and durable. It is said to be the most versatile of all printing processes. The padding press can print on substrate of any shape, thickness and size. Wide variety of substrate can be printed on this printing form including paperboard, paper, glass, plastic, fabrics, metals, nylon, cotton, and many others. Common products in overshadow include posters, labels, signage, decals and textile of all types and electronic circuit board.

Great thickness of the ink can be applied to the substrate which is an important characteristic of screen printing than any other printing technique. A very interesting effect is permissible in the process not possible in other printing methods. Wider range of inks and dyes are available for use because of the simplicity of the application process. Production rates have improved because of the increase in screen printing presses operation.

The development of the automated and rotational overlay press, improved dryers and UV curable ink is the result of the utilization of the press. Major chemicals used are screen emulsions, inks, and solvents, caustics, surfactants, and oxidizers used in screen reclamation. There is a dramatic variation in ink formulation.

There are three elements consist in the screen printing: screen which is the image carrier; the squeegee; and ink. A porous mesh stretched tightly over a frame made of wood or metal is used in the process. Mesh is made of porous fabric or stainless steel mesh. Accurate color registration in proper tension is essential. Manually or photo chemically, the stencil is produced on the screen. This defines the image to be printed referred to as image plates in other printing technologies.

Ink is applied to the substrate by placing the screen over the material. A paint-like consistency is placed onto the top of the screen. Ink is then forced through the fine mesh openings using a squeegee drawn across the screen. Ink only passes through the areas where no stencil is applied, thus forming image on the printing substrate. Thread diameter and thread count of the mesh determines the amount of ink deposited onto the substrate.