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Version vom 23. Juli 2009, 01:40 Uhr von MariusKintel (Diskussion | Beiträge) (Notes from screen print test session 23.06.09)
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Notes from screen print test session 23.06.09

  • Material bought from Wöco:
    • Screen with frame
    • Emulsion
    • Sensitizer
    • Paint
    • "Squeegee"
    • Cleaning agent to clean away hardened emulsion
  • Sensitize emulsion:
    • Fill up the small sensitizer bottle with water
    • Add to the box with emulsion
    • Stir well
  • Coat screen with emulsion
    • Do this away from bright light or sunlight
    • Use the "squeegee" to coat the screen with emulsion
    • Do this from both sides repeatedly to get an even coverage and an even surface as a result
  • Dry the coated screen (this will taka 30-60 minutes)
    • Place horizontally in a _dark_ room
    • To speed up, use a fan (occationally using a hairdryer might also help)
  • Prepare the design
    • Design a positive 1-color bitmap image (i.e. what you see is where the ink goes)
    • Print on a transparent foil using as dense ink as possible
    • Our printout was not very dense due to a broken/out-of-ink printer
  • Expose the screen
    • Place the screen with the flat side down on a horizontal surface
    • Place the printed transparent foil onto the screen
    • Mount a UV lamp lighting downwards with ca. 1 meter distance
    • We used the IR+UV lamp from the Chemielabor. Note! The UV lamp won't work lighting downwards, for some reason. Alternative setup: tape the transparent foil to the screen with _transparent_ tape. Cover the backside with something non-reflective.
    • Exposure time: 15-20 minutes. This depends on the thickness of the emulsion, too short and the opaque areas have not hardened, too long and thin lines in your design bleed together.
  • Clean away the non-hardened emulsion
    • Use warm/hot water with as much pressure as you can get from a shower head
    • Since our print wasn't very dense, this had an effect on the exposure: Less well-covered areas had clear half-hardened emulsion. These areas, in addition to areas with small details were a lot harder to wash away. Using a dishwashing brush helped a lot.
    • If some emulsion doesn't come off, use a small _plastic_ tool (e.g. a reprapped palm stylus) to _carefully_ scrape away the remaining emulsion.
    • Now, let the screen dry. Shouldn't take long.
  • Apply paint
    • Line up a bit of paint just outside the motive
    • Using the squeegee, carefully drag the paint over the motive so the whole motive is covered with paint
    • If it's not fully covered, drag it back again
    • Using a bit more pressure, drag the squeegee once over the entire motive
    • Carefully lift the screen from the motive
    • Every once in a while, clean away dried paint from the screen with water
  • Drying
    • Using a hair dryer, lightly dry the fabric
    • At this point, to make the print permanent, an iron should be used on the fabric. We didn't have one available, so who knows what will happen now..