3 Steps To Exposing A Screen
Preparing the screen is the most important step in screen printing. It is the catalyst for whatever your screen printing goals are and, if executed improperly, can ruin your whole project. Let’s run through the steps together so we can manifest our artwork onto the screen as cleanly as possible.
1) In a dark room using “safe” lighting; meaning either a red light or yellow bug light, pour photo emulsion into a scoop coater.
2) Hold screen at a 70 degree angle, place the scoop coater firmly against bottom frame on the front side of screen until. Gently tilt the scoop coater so the emulsion makes contact with the screen. Once the emulsion is touching the screen all the way across the coater, apply pressure as you pull coater from bottom to top of the screen. Stop approximately one inch from where mesh meets the frame. Tilt the screen back to a 90 degree angle and let emulsion fall back into the scoop coater. There is long standing debate on whether or not you need to coat both sides, but if you want to create a stronger stencil, flip the screen around and continue the same process on well side.
3) After applying the emulsion, let the screen dry in a dark, free of light, non humid area. Depending on the conditions within the dark room, this process can take up to 24 hours. You can use a fan to speed up the process, just be careful not to point the fan directly on the screen or at the floor. A dusty fan or dirty floor can affect the screen exposure process.
Expose Your Screen:
1) Once your screen is dry, you’re ready to expose it to light using your film. Be sure your artwork is printed onto a transparency allowing light to pass through the areas that aren’t printed. Your artwork needs to be dark (Rich Black is preferred) enough to block light from passing through it. That is how it exposes.
2) Place your artwork on the face side of screen (not the well side) and secure the film with transparent tape. REMEMBER: When placing the film on the screen, your image needs to be reversed/mirrored. After it is taped down, you can check it by looking at it through the well side. That is how it will print out.
3) Place the screen face down on the exposure unit. Be sure to clean off any dust on the glass. Otherwise those can become pinholes in your image later on. Each exposure time is different depending on type of emulsion, screen mesh and the type of bulbs in the exposure unit. It is best to use an exposure calculator to figure out your exposure time.
Rinse Out Image:
1) After exposing your image to light, the next process is washing it out. Wet your screen with low pressure on both sides.
2) Using low pressure, spray your image until it slowly appears; the emulsion will start to break down in the areas where your artwork was printed on the film. Be sure not to focus on one area for too long and risk blowing out your image. The washout process should not take very long. If it does, your screen has likely been overexposed.
Boom! There it is! You’re ready to start printing! Screen printing is an art that requires finesse and skill so, just like any other art form, practice makes perfect. Keep at it and you’ll develop your own touch for not only the processes explained above but also for achieving prints that will make professionals scratch their heads. Have fun!