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Notes from screen printing testout session 23.06.09:
- Material bought from Wöco:
- 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: Hard to say. I think we did ca. 20-30 minutes
- 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.