One of the most important aspects of screen printing use is fabric selection. Fabric selection is extremely important to the success of a screen printed design. Students who are learning screen printing should develop a background and knowledge of types of fabric and their application. Many people still refer to screen printing as "silk screen" printing. This is because originally silk was used as the fabric selection of choice when screen printing.
As designs became more complex, it was necessary to find alternatives to silk that were easier to use. Fabric manufacturers needed to have better control over the weave of the screen fabric "mesh", in order to have better control of their prints.
Think of screen fabric as a screen, like the one on a window or door. The openings allow air to pass through. In screen printing, the fabric openings allow ink to pass through. If there are larger openings in the screen fabric, more ink can pass through. Therefore, it is easier to control the ink deposit of the print, by controlling the size of the openings in the screen fabric.
With the development of new man-made fabrics such as polyester and nylon, it was much easier to control the weave of the fabric. Silk had an irregular weave. The reason for this is that silk is a natural fabric made from the material a silk worm uses to spin a cocoon. The size and width of the thread varies. This creates irregularities in the weaving of fabric from the natural material. This made silk a poor choice for complex designs and silk also left an irregular ink deposit.
There are two basic types of fabric that are used for screen printing today. They are as follows:
Multifilament Fabrics - Multifilament fabrics are made by twisting a number of threads together (like yarn or rope) to make a single strand. These fabrics are usually lower in cost and are easier to adhere certain screen stencil films to. However, multifilament fabrics usually result in lower quality prints and irregular ink deposits on the printed surface.
This simulated enlargement shows how multifilament threads are woven together, using several smaller threads to form one larger thread. Note that the irregular single threads combine to create larger irregularities when all are woven together. This accounts for the irregularities in natural fabrics, such as silk, as well as irregularities in certain synthetic multifilament fabrics. This is seen in the illustration below.
Monofilament Fabrics - Monofilament fabric consists of a single continuous thread. it is very similar to nylon fishing line. Monofilament fabric is usually more expensive. This is true, since there is a much higher quality control in the manufacturing of the fabric. This quality results in a very accurate spacing of the threads, and therefore the mesh openings are very similar in size. This allows for a very accurate control of the ink deposit and also results in a higher quality print. This fabric is usually used when creating direct (liquid coating) photostencils, since indirect films and other film stencils will not adhere or stick to the fabric very well.
This simulated enlargement of a single monofilament thread, shows no irregularities in the size of the thread. This is because weaving singular threads results in irregularities. Monofilament threads create monofilament fabric, by being woven singularly as shown below in the illustration below.
The table below is provided to outline the advantages and disadvantages of certain types of fabrics:
One of the most important considerations of fabric selection is the "mesh count". This term relates to the size of the openings in the fabric. As explained earlier, the ink passes through the openings in the mesh, resulting in the screen print. This is much like a screen door or window. If you were to try to pour water through a screen, it would pass right through. If you tried to pour molasses through the same screen, it would pass through, but more slowly. In order to get the molasses to pass through more easily, you could use a screen with larger spaces or openings in it. The same holds true when selecting fabrics for specific types of inks.
Inks for printing shirts are much thicker (like molasses or even peanut butter!) than inks for printing on surfaces such as metal or glass. Similarly, inks that are lighter in color are usually thicker than inks of darker colors. The screen printer must make the selection of fabric based on the ink that will be used, and the surface that they will be printed on. (Inks will be discussed further into the course.)
Multifilament and monofilament fabrics are labeled or numbered by a grading system. The system enables the screen printer to identify the size of the mesh openings or "mesh count" of the fabric. Sometimes this can be confusing. Monofilament uses one type of system, and multifilament another type of system. However, in both systems, the larger the number, the smaller the openings are in the fabric. This sounds weird, but that is the way it works! For example:
12xx fabric has smaller openings in it than 6xx fabric.
90 monofilament fabric has LARGER openings in it than 200 monofilament fabric.
When selecting fabric, be sure to consider the project at hand. There are other considerations as well. If the openings are very large, it is more difficult to coat a liquid stencil onto the screen. Therefore, an indirect film or extra coats of liquid (direct) stencil may be necessary. This knowledge will come from hands-on experience and trial and error, but a thorough knowledge of the material in this section will help you to select fabric correctly. Review it again when you get time, or ask your teacher some questions related to fabric.
Review the page again to be sure that you understand the material. REMEMBER, YOU WILL BE TESTED ON THIS MATERIAL!
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