Screen printing is a technique that is popular for making custom T-shirts and other fabric garments, but it is also used with paper. In screen printing, a block stencil is attached to a sheet of woven mesh. Screen printing is relatively fast and can be used to make a large quantity of identical items. The mesh is a key component to a quality screen print; the size, weight, thread and weave of the mesh will determine how precisely your design transfers onto a fabric garment.
A selection of mesh is typically organised by "mesh count," or the number of threads per square inch, such as 110, 180 and 240. The lower the number is, the larger the openings are that the ink will be pressed through onto your fabric; a higher number means more threads per inch and smaller openings that allow less ink to transfer. If the stencil has a lot of detail and small or narrow portions of the mesh are covered, then a high mesh count screen is appropriate. Larger openings will let in too much ink and potentially muddle the edges and details of the image.
Screen printing is sometimes referred to as "silk screen printing," because, in the past, silk thread was used to weave the mesh. Today's printing mesh is made of either polyester or stainless steel thread. Stainless steel thread screens are used for precision work like printing on materials such as glass and ceramic. For sign printing or garment printing, you will generally find polyester threads. Polyester mesh is woven with either monofilament or multifilament thread. Monofilament threads, single strands woven into mesh, are the most common. Multifilament threads are made of many very thin strands that have been twisted together and then woven into mesh. Multifilament mesh has the letters "xx" on the label.
The most common weaving pattern in screen printing mesh is called "plain weave" and will be designated on labels as "PW." It is a simple over-and-under weaving pattern. "Twill weave (TW)" is used to create thicker, sturdier screens and relies on complex patterns of weaving, which vary depending on the manufacturer. Twill weave mesh will be thicker than plain weave even if the mesh count is identical. The Screen Printing Technical Foundation compared the different weave's performance and found that twill weave transferred somewhat less ink than plain weave.
Printing mesh frames are typically constructed of wood or aluminium. Wood frames are inexpensive. The mesh attaches securely to the wood with staples or is held in place with a cord and slot. Aluminium frames are somewhat more durable and can withstand repeated dunks into water, ink and other chemicals and cleansers.
Aluminium frames are also lightweight, which makes shipping less expensive and saves you money in the long run. If you're looking to maximise performance in your shop, aluminium frames are a useful item to add to your screen printing equipment.