INDIRECT FILM PROCESSING INSTRUCTIONS
- Gelatin films will not perform correctly if stored in humidity less than 30%.
- Use a humidifier to increase the storage aread to an ideal of 50%
Step 1: PREPARE THE MESH
Used or surface-treated mesh need only be degreased using Screen Degreaser Liquid No. 3 or dilute Screen Degreaser Concentrate No. 33. New mesh that is not surface treated should be mechanically abraded. This increases the surface area of the mesh surface for a better mechanical bond of the stencil. Use Microgrit No. 2 before degreasing. Abrading and degreasing can be combined in one step with Ulanogel 23. Rinse thoroughly with clean water.
Step 2: EXPOSE THE STENCIL FILM
Place the emulsion side of a right-reading photo positive against the backing sheet of the stencil film in a vacuum frame. The positive should be between the light source and the stencil film, and the exposure should be through the backing sheet of the stencil film
From the Base Exposure Table below, select a Base Exposure Time corresponding to the film you are using and the light source you have. Multiply the Base Exposure Time by the factor for each relevant variable listed in the Exposure Variables Table below to find your Approximate Exposure Time. Use the Approximate Exposure Time as the central time in a Step Wedge Test, or with the Ulano Exposure Calculator.
Step 3: DEVELOP THE STENCIL FILM
Dissolve pre-measured A & B Developer Powders according to the instructions on the packet. (Hydrogen peroxide can be used if A & B Powders are not available. It should be diluted to a 1½% solution in a clean glass or plastic container using distilled water only.)
Place the exposed film, emulsion side up, in a developer tray. Pour the developer solution quickly and evenly over the film. Let the film develop for 90 seconds (180 seconds for UlanoPrex). Rock the tray occasionally to carry fresh developer across the surface of the film.
Step 4: WASH OUT THE STENCIL
Use a gentle washout spray preferably with an aerator nozzle to wash out the stencil at the recommended temperature. Water temperature will effect your washout time.
Recommended Washout Temperatures for Gelatin Films
Quasar R 100 : 36-40°C | 97°-104° F
Super Prep : 38-41°C | 100°-105° F
Red TI : 41-43°C | 105°-110° F
UlanoPrex : 43-49°C | 110°-120° F
Wash out the film for several minutes until all the unexposed emulsion has been washed away. Then, gradually lower the temperature of the water to room temperature. Continue to wash for 30 seconds.
STEP 5: ADHERE THE STENCIL
Place the washed out film, emulsion side up, on the buildup board. Gently lower a properly prepared, damp screen, printing side down, onto the film. Place a pad of newsprint (unprinted newspaper stock) on the squeegee side of the screen. Wipe over the newsprint pad with a folded rag or print roller to blot the soft top layer of the film up into the mesh. Remove the bottom sheets of wet newsprint, and continue blotting. Repeat this procedure until the newsprint picks up little or no color from the film emulsion.
Problems adhering usually come from old film, developing in water hotter than recommended, or over exposure.
Step 6: DRY THE STENCIL: REMOVE THE BACKING SHEET
Dry the adhered stencil thoroughly with cool air. When the mesh surrounding the film is dry (and before the stencil is dry),with the plastic support still in place, apply Screen Filler No. 60 or Extra Heavy Blockout No. 10 to the open area of the screen. After the stencil and blockout have both dried, peel off the plastic support.