First things first, you’ll need an exposure unit, which is a machine to transfer the image onto the screen. The cost of the exposure unit will depend on the size of your projects. If you plan on printing smaller items, such as ’zines, invites, and tees, a 16” x 20” unit will do the trick. For screen printing larger-scale items such as posters, you might want to look into getting one that’s 20” x 24”. While it won’t take up too much space, note that an exposure unit is pretty heavy, as it’s made of aluminum, so you’ll want to have a designated space for it so you won’t have to keep moving it around.
Film positives, or transparencies, are what you use to copy your image onto the screen. These thick, waterproof transparencies are essentially stencils that you put on top of your screens in the exposure unit to transfer the image. Just make sure it’s a high-res file in the darkest black. (If you want to get specific, at least a 300-dpi, spot color image works best.) If you’re foraying into screen printing for the first time, you might want to try out one color initially. If you’re printing in more than one color, you’ll need to make a separate transparency for each color.
The image elements for each color also need to be separated out. For instance, if you are printing in red and black, you’ll need a stencil for parts of your image that are red, and another stencil for the parts that will be in black. As for thickness, a 4-mil transparency should suffice. Of course, before purchasing, make sure the kind you’re buying is compatible with your printer.
Once your image has been transferred to the screen, that’s when the screen printing fun truly begins. To transfer your image onto the fabric or cardstock, you’ll need a few frames with fine mesh cloth stretched over them. While you could use wooden frames, aluminum ones, while a little more expensive, are easier to clean and generally last longer. The mesh comes in different counts, ranging anywhere from 40 to 300, where a 110 mesh count is considered the average and is most commonly used.
The higher the mesh count, the finer the holes are in the screen. For instance, a 100 mesh count means 100 threads in a square inch. While a high mesh count means the greater the detail you’ll capture in your image, you’ll be able to deposit a smaller amount of ink. These screens will be reused time and time again, so invest in some quality ones if you can.
Before putting your transparency and screen in the exposure unit, you’ll need to apply a thin layer of emulsion on the screen and set it aside to dry. All dry? You’ll then place the transparency on top of the mesh screen and expose it to light. What happens next is that the light hardens the emulsion on the screen. On the other hand, in places where the light is blocked—that’s where your image is—the emulsion is water soluble.
A little bit of ink goes a long way, so depending on how many units you’re looking to shift, you might just need a small container of ink. As to what kind of ink to use, it’s oftentimes a matter of preference and trial and error. Most screen printing inks are acrylic-based, and some are better for fabrics while others are optimal to use on paper. Some brands you’ll find to be less watery than others. Just be sure to get the kind that’s made specifically for screen printing.
For every handcrafted creation you make, whether it be a tote, tee, or poster, you’ll need to do a “pull,” which is pulling the ink onto the surface of the fabric or cardstock. Squeegees for silk-screen printing vary in the length, hardness, and shape. If you plan on doing a variety of different projects, then getting a set would be most helpful in getting you started.
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