Silkscreen Printing

This wiki page contains my recollected notes of making and using a silkscreen to print shirts. In silkscreen printing, one makes a resist that blocks the transfer of ink onto the shirt/bag/poster/whatever. This resist is a negative of the image to be printed, and has to be attached to the silkscreen. This approach uses a photosensitive resist medium which is painted onto the screen and then exposed to light to make the pattern on the silkscreen, and uses the vinyl cutter to make the initial mask for the resist.

This will give you some rough ideas on how to make a silk screen. This is a novice's recollection - you have been warned.

The basic steps are:

1. make a pattern and cut it out on the vinyl cutter
2. use the pattern as a mask to expose and UV cure a photosensitive resist on the silkscreen
3. use the silkscreen to apply ink to the item being printed upon by pressing ink through the holes in the silkscreen with a squeegee. Where the ink is NOT blocked by the resist, it is applied to the printed item.

If you are going to just do one or two prints, you might get away with using the vinyl AS your silkscreen resist (and save yourself a bunch of time) before it starts to peel up and ruin your edges/lines. More often the vinyl is used to make a mask for the photosensitive resist, and is removed once the resist is UV cured.

Making the Silkscreen

1. Apply the light-sensitive liquid resist to the clean/new silkscreen panel with a disposable paintbrush. Smooth is good. Complete coverage is mandatory.
2. Wait for the resist to dry...in the dark.

   While the resist is drying,

3. Make/load a black and white line art file and "print" it on the vinyl cutter. This assumes you know how to use the vinyl cutter.
4. Use an Xacto blade to pick out and remove all the parts of the vinyl NOT a part of the resist. The parts you keep are where you want the ink to be put on the shirt. For example, with text to be printed, you would removed the vinyl from around the text, but leave the letters themselves in place. This can be a little or very tedious/labor intensive, depending on the pattern. Tip: Using vinyl similar in hue to your shirts might make this easier to keep straight. Then you remove the shirt from the mask. Alternatively, make the mask match the ink, and leave the ink intact and the shirt "clear".
5. Use the semi-sticky sheeting to attach the vinyl resist and remove from backing. This preps the pattern for attachment to the silkscreen by placing it "sticky side out" on the semi-sticky sheeting.

   Once the resist is dry,

6. Carefully place the vinyl on the resist. Press down for crisp edges.
7. Expose the resist to light to cure it (in a controlled-light environment). Wait some more while the light does its thing.

   Finally, to clean up the silkscreen

8. Use water (in a sink works) to wash the uncured resist (and the vinyl mask) off of the silkscreen. If all goes well, the cured resist will remain, while the resist that was under the vinyl (and protected from light) will wash away. This will leave the fine silk mesh exposed that will allow ink to pass through onto the item.

Steps 1, 2, 6, and 7 need to be done in near-darkness. This was done in the Darkroom at the old space. Perhaps the Paint Booth could work in the new space. Include signage/plan ahead to prevent disasters from light leakage. Step 8 needs to be done quickly, less the resist under the mask begin to cure while you are cleaning it off.

No specific timing, etc. is provided in the above because I did it with Pearce last spring, and only once. I've slept since then and short term memory fades....

Using the Silkscreen

1. Place the prepared screen in the jig. Up to four screens can be used for multi-color prints, though care needs to be taken to get them aligned. The frame should be up, so that the flat of the silkscreen can contact the item.
2. Place a shirt, bag, etc. under the screen. Spray-tack can be used on the deck to keep the item from slipping.
3. Apply some ink on the top of the screen.
4. Lower the screen onto the shirt
5. Squeegee ink across the screen, pressing the ink through the silkscreen and onto the shirt.
6. Lift the screen.
7. If I recall correctly, we used heat to cure the ink at this point.
8. Rotate jig to put next silkscreen in place (if doing a multi-color print).
9. Lather, rinse, repeat steps 2-7.

Practicing on paper before moving to shirts strongly recommended in order to prime the silkscreen, test placement, etc. etc.

Things I Learned/Did Wrong

1. It takes longer than you think: much longer. Once the prep work is done, you can crank out shirts fairly quickly, but plan on several hours getting to that point.
2. Pearce is very patient - thanks again, Pearce!
3. Use vinyl similar to the shirt color (light for light shirts, dark for dark shirts at least) to make cleaning the vinyl from the resist more straightforward.
4. Not getting the screen all the way down. This allows ink on the underside of the screen, and will botch many shirts.
5. Using a pressure washer to clean the screens is good, but you can punch a hole through the screen you just bought at Hobby Lobby the day before, and end up junking it.