Silkscreen Printing Unit Lesson 3: Preparing and Exposing Photographic Silkscreens

This is an image of a film positive on top of a light table. The light table had four fluorescent lights underneath a glass top. There is a black clock timer in the background. — Photo by Sean Carroll

This lesson walks students through the process of coating silkscreens with light sensitive emulsion, drying coated screens, and exposing screens using their film positives.

Objectives

Students will learn how a source image is exposed onto a silkscreen.
Students will apply the proper steps of coating, drying, and exposing their images onto their silkscreens.

Vocabulary

Photo emulsion: A light sensitive chemical that is applied to a screen and used to expose an image onto the screen.
Scoop coater: A metal trough used to apply a smooth, even coat of emulsion to an open silkscreen before exposing the image onto the screen.

Discussion Questions

Review the Preparing and Exposing Photographic Silkscreens Powerpoint, then ask students:

How is an image transferred onto a silkscreen?
What does it mean to “expose” an image onto a screen?

This is an image of a student pouring photo emulsion into a metal scoop coater. The photo emulsion is a bright pink and fills one half of the scoop coater. — Photo by Sean Carroll

A student pours photo emulsion into a scoop coater.

A student pulls a metal scoop coater filled with bright pink emulsion up the screen. The emulsion creates a big pink rectangle in the middle of the yellow screen. — Photo by Sean Carroll

A student pulls a scoop coater across the screen to coat it.

A student places a coated silkscreen underneath a wooden cabinet.

A student places a coated silkscreen on top of a film positive then onto a large light table. This light table has around twenty fluorescent bulbs and a black cover that goes over the table. — Photo by Sean Carroll

A student exposing a film positive onto a coated silkscreen on a light table.

A student washes out a silkscreen using a hose, in a large sink. The sink has black plastic on the back and side walls. — Photo by Sean Carroll

A student washes the emulsion out of an exposed silkscreen.

A student holds a silkscreen up to the light to check that it is clean. He checks to see if there are any holes in the image on the screen still clogged with ink. — Photo by Sean Carroll

A student checks a silkscreen to see if it has been properly cleaned.

Materials

Powerpoint: Preparing and Exposing Silkscreens
Screen printing emulsion for water-based inks
One open silkscreen for every five students
One silkscreen per student for the photographic layer (or two students per screen if screens are limited)
Students' film positive transparencies
Dishwashing liquid for cleaning ink out of screens
Scoop coater
Light-tight box or dark room
Exposing unit
Comet cleanser for degreasing the screens if they are brand new

Procedure

Review the Preparing and Exposing Photographic Silkscreens Powerpoint as a class.
If your screens are new, clean them first with Comet to degrease the screens.
Read and follow all of the instructions that come with the emulsion. Sensitize the emulsion, stir, and let sit for sixty minutes to allow time for the air bubbles to rise to the surface.
In a darkened room or in a room with a yellow safe light, coat silkscreens with the emulsion and scoop coater. Follow the directions included with the emulsion.
Store the coated silkscreens in a dark room or light-tight box until they are dry. Screens may be stacked on top of each other using blocks in between to save space. Screens should dry with the flat side down.
Once the screens are dry they may be put in black plastic garbage bags until you are ready to expose them.
Expose the silkscreen with the students’ film positives. A screen exposure chart should be included with your emulsion. If not, you will need to test exposure times. A good time to start with is five minutes.
Immediately following exposure, wash out the screens with water and a sponge, or a spray nozzle if you have one in your classroom. You will see some of the emulsion begin to leave the screen in the areas that were protected by the image printed on the film positive. Follow the wash-out instructions included with the emulsion. Dry the screens completely before the students print their first layers.

Wrap-up

When all groups are finished exposing and drying their screens, complete the following:

Have students use masking tape to tape off the areas around the edges of the screen where there is no emulsion.
Have students pull a proof of their silkscreens to ensure that the image was exposed properly.

Assessment

The following assessments can be used for this lesson using the downloadable assessment rubric.

Communication 3
Communication 4
Creative process 2