Consider this part two of a three-part series on how to screenprint! We'll go into more detail about how to prepare your artwork for screen printing and how to print in future posts. Right now, you're ready to go if you have artwork handy on a transparency and the supplies below, which can be found around your home and at most art stores.
Burning a screen is the process of putting your artwork onto the silk screen, creating areas on the screen that will block out the screen ink, and areas that let it through (like a stencil). To achieve this we use screen print emulsion, which is a UV-sensitive liquid that creates an ink-resistant film on your screen. UV light "fixes" the emulsion to your screen, so any areas not exposed to light will wash away with water. These areas not covered in emulsion allow screen ink to be pressed through the screen in the printing process.
What you'll need:
Framed silk screen
*Emulsion and sensitizer
Vinegar and dish soap
Squeegee or credit card or if you're fancy a proper scoop coater
A darkened room
Black bristol board, paper or black cloth or felt
**Art work on a transparency
Sheet of glass bigger then your art work
Clear scotch tape
Light fixture with a 150 to 250 watt photo flood bulb
Sink with a spray nozzle or go outside and use the garden hose
*Most art supply shops sell the emulsion and sensitizer kits. Follow the manufactures directions on how to activate it's super powers. Usually you add water to the sensitizer, stir and then add this mixture to the emulsion, stir again and voila! But read the instructions for the exact technique.
The emulsion is light sensitive. This is very important to know. You don't want to dawdle when working with it. A lot of screen shops do this process in a dark room with a photo light (red light). We don't. We like to work in a day-lit room where the sunshine isn't pouring in and the lights are dimmed. Emulsion also expires! To avoid sadness, make sure your emulsion has lots of life left in it before starting.
**A note about art work on a transparency: You can get this made at a copy shop or even do it at home with a printer and transparency sheets. The transparencies should be black and white (aka clear) and look like what you will eventually want to print (ie, you don't want a negative image, as with film).
Prep your screen
Wash your fresh new screen with dish soap and vinegar, and rinse well with water and let dry. Don't touch the fabric part of the screen after you have washed it, you want to keep this area clean of dust, dirt and oils so the emulsion in the next step adheres well.
Applying the emulsion
Once your screen is completely dry you are ready to coat the screen with the activated emulsion. Pull on rubber gloves unless you want to live on the edge like Trish, above. Pour a few table spoons worth of emulsion on your screen and spread a thin layer over the screen using a squeegee. Flip your screen over and evenly spread the emulsion that has seeped through. Squeegee off all excess emulsion on all sides, you want your emulsion to be as thin and evenly coated as possible. Scrape excess emulsion back into the container. Close the container and put in a cool, dry, dark place till next time. Lean the coated screen in a dark place to dry and make sure nothing is touching the wet area. It will take a few hours to dry but you can speed this up with a fan.
Clean the squeegee with water right away, emulsion is hard to clean once it dries.
Once your screen is dry, you are ready to burn the image of your artwork onto it. You'll need your transparency, scotch tape, coated screen, black fabric or bristol board, glass, photo light, and timer.
Your glass can be any size as long as it is bigger than your art work. Hang your light bulb directly above the screen at a height about same as the width of your screen.
We are going to make a sandwich. Set your foam down directly under the light, then place the black bristol board or fabric on top. Now place your screen on top of this and tape your transparency to the screen. Complete the sandwich with the glass. Set your timer to the correct time, there is usually a guide that will come with your emulsion - follow those instructions! (We use a 400 watt bulb at 6.5 minutes and previously we used a 250 w bulb for 14 minutes.)
When the time is up, turn your light off, set aside the glass and the art work. You will notice an image of your design on the screen - yay!!
Washing your Screen:
Take your screen over to the sink and spray both sides of your screen with water, it's safe to work in full light now. Let it sit for 30 seconds.
Hose your screen down to wash away the emulsion where your art work was. This can take anywhere from 2 to 5 minutes. Don't be afraid to use the pads of your fingers to help it along, but don't over do it. Hold your screen up to the light and make sure all your emulsion is washed away where your design is.
Let your screen dry completely.
Now all your hard work has paid off and you are ready to print!
Stay tuned for our next post in this series... and to see what we make with our new Sloth screen :)