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Screen printing is a little more complicated than using vinyl or iron-on transfers, but the results can be spectacular. Instead of adhering an image to the surface of a shirt using transfer paper and an iron, screen printing uses a stencil and ink that is screenprinted directly onto the shirt to create the image. The result is a shirt with an image printed on top of its fibers.
Getting started with screen printing requires some materials. You’ll need:
Printing screen and frame (available at craft stores)
Photo emulsion and sensitizer (also available at craft stores)
Yellow bug light
A desk lamp
A 250-watt bulb or 500 watt halogen light
A dark room
Silk screen fabric ink
A piece of cardboard slightly larger than your design
Black garbage bags
Inkjet or laser transparencies
Create your artwork using Photoshop or other artwork editing software. For beginners, we recommend starting with a single-color image such as block text or a silhouette. More advanced screen printers can experiment with multiple colors.
Using a multi-color image will require you to use artwork editing software to separate the image into layers, with each layer representing the multiple colors of the image. Single-color images only have one layer and do not require separating into layers.
Print each individual layer of your image onto a clear transparency using black ink. The easiest way to do this is to print your transparencies using an inkjet or laser printer. Make sure the black ink is really dark and opaque.
Preparing the Screen
It is very important that you prepare your screen in a light safe room that is free from UV rays. To do this, pick up a yellow bug light from your local hardware store and swap out your standard light bulb. This will allow you to have light, but will not pre-expose your screens until you’re ready.
Wearing gloves, mix the emulsion and sensitizer together according to manufacturer’s instructions. Remember that this must be done in a light safe space!
Now, there are a couple of ways to coat your screen with emulsion. The first is to put down a black garbage bag and lay your screen and frame on it. Then, pour enough emulsion on your screen to coat it completely, and use your squeegee to evenly spread it across the screen.
Another, more efficient way to coat your screen with emulsion, is to fill a scoop coater with emulsion, use a screen coating stand, and coat both sides of your screen with emulsion. The emulsion should cover as much of your screen as possible and must be a larger area than the image you’ll be printing. When you’re finished, you should have a thin, even layer of emulsion. Let the screen dry for no less than 4 hours, but ideally for 12-24 hours.
Now, you’re going to need a very dark room free from UV rays. A closed closet works, as does a dark bathroom with a small yellow bug light. If your room has windows, make sure and cover them with black plastic bags to prevent light from getting in.
If you do not have an exposure unit specific for screenprinting, there are a couple of options to expose your image onto your screen. First, lay your emulsion coated screen on a black surface with the emulsion coating facing up. Next, tape the image transparency reversed on top of the emulsion. Some printers additionally secure the transparency using a piece of flat glass as this helps reduce any space between the transparency and the screen. This is called positive contact and it helps prevent light from creeping in between your transparency and your emulsion coated screen. Using glass from a picture frame is an easy way to do this!
Now, if you’re using a lamp with the 250-watt bulb, position it so that it’s one or two feet away from the image (make sure the lamp you use can handle that much wattage, to reduce the risk of fire or electrical shorts). Angle the lamp so that the light directly shines on the image and leave the room for about 10 – 15 minutes. Keep in mind, the closer the light is to your screen, the less amount of time you need to expose. This will take some time to dial in your exposure times!
For a quicker exposure with less variance, use a 500 watt halogen light, position it 16 inches above the center of your screen, and expose for 12 minutes 30 seconds to 13 minutes 30 seconds. If you’re using an image with multiple colors, repeat this process with each transparency that represent the colors of your image.
Rinse and dry the screen. As you do so, you’ll see the emulsion rinse off where the exposed image is. Continue rinsing until the burned emulsion has washed off completely and you can see the image clearly.
Let the screen dry completely. Using a blow dryer can speed this process up, but be careful not to get too close to your screen when using a dryer.
Next, using tape, tape the perimeter of the screen that doesn’t include the image and is not covered with emulsion. This prevents the screen printing ink from passing through the mesh or silk screen and getting on your shirt in areas that you don’t want it to.
Time to Print
Lay the shirt on a flat surface, placing the stiff cardboard inside the shirt and directly under where the image will be printed. Align the screen over the shirt.
Pour a small line of ink across the top of the screen. Using the squeegee, pull the ink down the screen in a smooth motion, maintaining pressure as you do. Even pressure is important and will ensure that the ink passes through the screen and prints your complete image. Pull the squeegee and ink multiple times if needed!
Now, lift the screen and carefully remove the cardboard from the shirt. If you’re using a single-color image for your screen printing, you’re almost done.
To set the ink so it doesn’t wash out, you need to use heat to cure the ink to 320 degrees. A heat gun or flash dryer is ideal, but it you don’t have these, you can set the ink by heating an oven to 400 degrees and putting the shirt in for thirty seconds, checking the process every step of the way to prevent fire. Using an oven is not optimal, so heading to your local hardware store to pick up a heat gun is your best bet. While you’re there, you may also consider grabbing a temp gun that will let you know what temperature your ink is curing at. This is the best way to know that your ink has reached 320 degrees and will not wash out.
If you’re screen printing an image with multiple colors, you need to repeat the process of printing and curing your ink for each color in your image. The extremely tricky part is ensuring that each transparency lines up exactly with your previously printed ones, otherwise the image will come out misaligned, blurry, and have overlapping colors.
As for the screen, if you want to use it for more screen printing, you can store it, emulsion and all, in a dark place. After cleaning off all of the ink, black garbage bags work fine for storage. But, If you decide you’d like to use it for another screen printing project, you can clean it with an emulsion remover, dry well, and start over- keeping in mind to follow the emulsion remover instructions closely. Do not let the emulsion remover dry on your screen!
The process of screen printing can be intimidating, but if you start with single colors, practice and follow the instructions, you’ll soon get the hang of it. Happy printing!