How to Expose Halftones.

Follow these Standard Operating Procedures (SOP’s) to ensure the best results on press:

  • Screens are properly coated and free of dirt, dust, and debris. See our SOP for coating screens.
  • Exposure unit glass, and blanket is free of dirt, dust, debris, and ink.
  • Make sure your film has the emulsion side of the film against the emulsion of the screen.
  • DO NOT let your film come into contact with dust, dirt, or lint. Keep it as clean as possible. Store your film appropriately.
  • Ensure your film gets proper positive contact with the emulsion of the garment side of the screen when exposing your art. At no point should there be any gap between the film and emulsion of the screen.
  • Keep the screen dry prior to exposing your image to avoid pinholes, or the emulsion falling out.
  • Be sure you have your screen exposure times dialed in. Run through the necessary screen exposure time tests to calculate the proper exposure time for your setup.
  • Do not overexpose your halftone image(s). Doing so will start to close up the halftone dots.
  • Make sure you are using a diazo or dual cure emulsion for the best results. Do not use a photopolymer emulsion.
  • Gently apply water to both the front and back of the screen at facet pressure. Working both the front and back evenly until the emulsion starts to fall out. Failure to do so could result in rinsing out halftone dots.
  • Once the emulsion starts to fall out, apply water pressure from the garment side only. Facet pressure is ideal here, but as you get more experience, you can use a power washer to rinse the screen out the rest of the way.
  • Once your image rinses out, STOP! Do not rinse the screen more than necessary as this will lead to rinsing out halftone dots.
  • Use light water pressure around the image area on the inside / ink side to gently wash away any underexposed emulsion.
  • Getting a head start with an air hose at light pressure is acceptable. Apply compressed air mainly from the garment side.
  • Post exposing the screen on the exposure unit, or out in the sun will help harden the emulsion, increasing it longevity on press.

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