Section C – Step-by-Step Instructions for Screen Printing
using the teeshirtprinters.com single color press

Now, we will cover step by step, every single step of making your first print. This section will be very detailed, so read through it carefully several times.

Step One – Coat your screen with emulsion

If you have ever handled presensitized lithographic plates, you already know how to handle your diazo emulsion. Incandescent light, if subdued, is not immediately harmful to the emulsion. You should limit the exposure of the emulsion to light, but do not have to totally eliminate light from the room you are working in. A windowless bathroom, with a 5-watt night light, is perfect.

If you bought diazo emulsion, you’ll need to add the sensitizer. The brand I recommend is shipped with a small bottle filled with powder. Fill the bottle ¾ full of warm water per the instructions. NOTE: This is the most staining substance known to man! If you get any on your skin you’re tattooed with diazo activator for several days. More importantly if it gets on your bathroom counter your wife is going to kill you, because it is probably ruined for life.

Adding the diazo sensitizer is now just a matter of shaking the bottle and pouring the mixed activator into the container of emulsion. Then stir thoroughly (several minutes) with the paint stirrer the manufacturer provides (or use your own).

You need to let the emulsion sit for an hour or two. There will be air bubbles rising to the top during this time. The air bubbles will create pinholes in the coating if you don’t allow them to escape before using your emulsion. You can speed the process somewhat by dropping the container flatly on its bottom from a height of a couple of inches, every ten minutes for an hour. This usually does the trick of freeing all the bubbles.

Assemble your scoop coater while the emulsion settles. It will arrive as a single piece of extruded aluminum, with a pair of hard plastic end caps and a plastic cover. Put a light coat of silicone in the grooves of the end cap that fit over the ends of the aluminum piece, and pound them on. Once the silicone is dry, take your emulsion and your scoop coater into the room you’ll be coating your screen in. We now need to assemble your drying box.

Simply put the mailing tubes in the bottom of the box, with enough distance between them that the screen frame rests on the outer edges. If you want to get fancy, you can glue the tubes into the box, with one end of each tube butted against the side of the box. Cut a hole in the box to let air enter the tube, but not so big that light escapes around the edge. See the diagram included at the end of this tutorial. What you’re going for, is you want to be able to dry the coated screen by laying it across the mailing tubes and covering the screen with the box lid. You don’t want anything touching the print area of the screen.

If your drying box is ready, and the scoop coater silicone is dry, and the emulsion has settled, and no one has just been in the bathroom making it so you don’t want to go in there, take all your supplies in and we’ll coat the screen.

Fill up your scoop coater with emulsion, about ¾ of the way full. With your strong hand, grasp the coater firmly in the center. Hold the screen portrait style (longest top to bottom) with your other hand, with the ‘squeegee side’ towards you. Tilt the screen at a 45° angle, and place the lands or flat spots on the scoop coater end caps against the screen. It is imperative that the scoop coater be held flatly against the screen mesh. Now, tilt the screen vertical and in as smooth a stroke as you can manage, coat the screen with emulsion by moving the coater from the bottom to the top. As you near the top of the screen you’ll need to tilt the screen back to you and keep the emulsion inside the coater from spilling out when you reach the end.

Coat the ‘work side’ of the screen in the same manner. Some people do two coats each side, but I recommend one for beginners. It may take a few tries to get a good coating you can work with. If you have four coats of emulsion it will be a lot harder to wash out than if there are two, and two will work just fine for short runs. Using four coats is supposed to extend the run life of the stencil, since it won’t wear down as quickly. It also helps prevent pinholes since it is a thicker coating. Eventually you’ll want to try four coats, but just do two for now.

Now, place the screen, squeegee side up, in the drying box. Cover it, and let the screen dry.

NOTE: Emulsion, especially diazo emulsion, is very sensitive to water and humidity. Don’t let the humidity get outrageous in the area your screen is drying in.

Check your screen after a few hours. It is dry when it looks and feels dry (duh).

Now you’re ready to burn an image into the screen!

NOTES
· No one in history has ever coated a screen perfectly on the first try. My first two tries were totally unusable. Don’t get discouraged if you mess up. Emulsion rinses out, and screens are reusable. Screen printing looks simple, and it is – but good screen printing is a skilled trade, like a carpenter or an electrician. It will take several tries to get to the point that you are really good at this.
· You may benefit from practicing the coating of your screen without filling the scoop coater with emulsion. A smooth, steady motion is absolutely necessary and a bit of practice goes a long way!
· Don’t get the emulsion on so thick it drips. Drips are bad – very bad. They cause blurry prints and underexposed designs at best, and at worst they ruin a screen. Repeat: Drips Bad.

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