01 Apr The Screen Printing Process
Screen printing is a way of transferring a stenciled image onto a substrate, such as fabric, ceramic or other surface. It dates back to 960 AD when the Chinese were the first to employ this method. Screen printing gained popularity during the 1900s and is now one of the main ways to mass reproduce images. It is a very popular way for businesses to add their logos or other imagery to promotional items because it is inexpensive and rich in detail.
The first step in the screen printing process is for a mesh to be chosen. A variety of textiles will work as a screen printing mesh. The different size of the holes in the material change the depth and intensity of the image they create. Polyester is the most common mesh used in modern screen printing, but there are others. Once a mesh is chosen, it is stretched across a frame to keep it taut while it’s being worked with.
The next step is for a stencil to be made and applied to the mesh to direct the ink into the proper areas of the design. The most common way for stencils to be made in recent years is through photo emulsion. This is similar to creating a negative for a photo. The closed space, or positive space keeps the ink out, and the open space, or negative space let’s the ink through, creating a positive image on the substrate.
To create a stencil on the mesh, a photo sensitive emulsion is applied to the entire screen, and then it is left in a dark room to dry. Next, the desired image is photocopied or printed onto a transparent sheet, making the areas meant to be printed not transparent. In the dark room, the printed transparency is laid over the top of the photosensitive mesh, and then it is exposed to light. The light burns the exposed area of the emulsion, fastening it to the mesh. The unexposed areas can then be rinsed away, leaving behind empty, or negative space where the positive image can be pushed through.
The final step in creating a screen printed image is to apply the ink. The framed and stencilled mesh is placed flat over the chosen substrate, which is secured down flat as well. The ink is then applied by sweeping it across the screen, and pressing it through with a rubber blade, or squeegee.The open holes in the mesh allow the ink through, while the closed ones block it. This creates the image. The excess ink is collected in a reservoir and the other end of the screen to be used on the next print. The screen is lifted, the substrate is removed, a new one is put in place, and the process is repeated as many times as desired using the same screen.
There are some extra steps to keep things taped down and cleaned properly between each printing but this is the basic screen printing process. The whole thing can be accomplished very rapidly using industrialized machines which work at a rate of 1,805 prints per hour, down to the slower speed of doing one print at a time by hand. The versatility of the screen printing process and the affordability of materials is partly why it has become so widely popular.