Goal

The goal of this exer­cise is to develop the proper tech­nique for cre­at­ing a photo emul­sion stencil.

Objective

The objec­tive of this exer­cise is to expose and wash out a screen in prepa­ra­tion for printing.

Background Reading

• Mac­Dougall, Chap­ter 5, p 53–65

Safety Notice

• Do not look directly at the ultra­vi­o­let light
• Safety Data Sheet (SDS) Index

Exercise

A prop­erly exposed screen is an essen­tial step in cre­at­ing a print. Film pos­i­tives are black and white sep­a­ra­tions for each color. These films block light in some areas, which pre­vents expo­sure and, after washout, allows ink to flow through the mesh and onto the substrate.

Part One

Open the lid to the expo­sure unit. Using the pro­vided film pos­i­tives, place the fol­low­ing in this order:

1. Film (right reading)
2. Screen (squeegee side up)
3. Black foam block (flat side down)

Place­ment of the film in the cen­ter of the screen is key. Use the pro­vided guides as a ref­er­ence. Space on all sides is needed for a proper print. If needed, lightly tape the film to the screen but pay care­ful atten­tion to sides and order. Close and latch the lid on the expo­sure unit.

Warn­ing: Be care­ful with the metal frame and the glass. Glass can eas­ily scratch or break caus­ing injury.

Part Two

Set the timer on the expo­sure unit to 7 min­utes, which is the pre­de­ter­mined time estab­lished for this film-emul­sion-screen-light com­bi­na­tion. Start the timer and con­firm the light is working.

Warn­ing: Do not look directly at the ultra­vi­o­let light. Doing so could cause per­ma­nent dam­age to eyes.

Part Three

Ensure washout booth back­light and water are turned on. When the timer on the unit buzzes, switch it to off. Care­fully open unit and remove foam, screen and film. Take only the screen to washout booth.

A faint image of the film should be vis­i­ble. Gen­tly spray both sides of the screen ensur­ing it is entirely wet. Count about 15–30 sec­onds and then spray with full pres­sure on the print areas. The emul­sion should start to leave the unex­posed areas show­ing the yel­low screen. Con­tinue in a right to left, top to bot­tom pat­tern ensur­ing all print­able areas are uncov­ered and clear.

Lift the screen into the back­light and care­fully check the areas for block­age. Pay atten­tion to small details, such as reg­is­tra­tion and trim marks as they are the first to fill in. If any block­age is found, con­tinue to wash out from the print side. As a last resort, use a scrub brush to lightly open the area. If it does not open, notify the instruc­tor. Some areas may not have been prop­erly exposed.

Squeegee all excess water into the sink. Wipe the screen with a paper towel to remove stray drips and pud­dles. Place the screen in the light of a nor­mal room to dry.

Technical Specifications

• Ulano LX-660 emulsion
• 20 x 25 230 yel­low screen
• 7 min­utes on timer

Assessment

• The fol­low­ing rubric posted on D2L will deter­mine assign­ment score: Exer­cise Grading

Techniques

Expo­sure, washout, drying

Supplies

Expo­sure unit, film, coated screen, foam block, washout booth, squeegee, paper towels

Deadlines

Monday/Wednesday, Jan­u­ary 30/February 1, 2017. Exer­cise Given.

Monday/Wednesday, Jan­u­ary 30/February 1, 2017. Observed by instruc­tor as part of group demonstration.