Screenprinting Setup

Supplies

Exposing & reclaiming screens

• Speedball photo emulsion (& catalyst) Suppliers: Dick Blick (online); Artist & Craftsman (usually stocked in store)
• screen reclaimer
  • Holden's HO-100 powder screen reclaimer. Supplier: Standard Screen Supply.
  • Gem-Zyme concentrate emulsion remover, which can be diluted 20:1. Supplier: Anthem Screen Printing Supply
  • Speedball also has a reclaimer product; haven't tried it.
• Eiko 250W 500W photoflood light bulb Suppliers: Amazon Stay away from Sylvannia bulbs. They have a bad reputation.
• lamp with a ceramic socket that can handle the 500W bulb
• red bulb (optional) for that lightroom feel while exposing screens
• high pressure nozzle to clear ink and emulsion out of the screen
• nitrile gloves

Ink

• Speedball acrylic permanent ink Suppliers: Dick Blick (online for quart jars); Artist & Craftsman
• Extender Base, for adding transparency to inks. Suppliers: Dick Blick (online); Artist & Craftsman

Screens

• Mesh: 180T monofilament Supplier: Screen Printers Resource
  Very important to use only monofilament mesh for sharp images on paper.
• Nylon tape to hold down mesh
• staples (& staple gun) for stretching mesh
• tape to water-proof frames
• Haven't needed to purchase frames anytime recently.

Misc

• Painter's tape for holding down clips
• Registration clips
• Clothes line and binder clips for hanging prints to dry

Screen preparation

Stretching screens

Materials

• screen frame (TK: suppliers)
• mesh (see above)
• staple tape Nylon ribbon to hold staples. suppliers: Standard Screen Supply, Anthem Screen Printing Supply
• staples & staple gun (TK: staple size)
• "block out" tape waterproof, solvent-resistant tape (TK: suppliers)
• stretcher pliers (suppliers: Dick Blick)

Process

TK

Coating screens

Materials

• Emulsion
• Emulsion scoop
• Sturdy ledge (chair or something comparable with a sturdy vertical surface to lean the screen on)
  Check out this solution; it would be simple enough to screw a couple of strips of wood to the bench.
• Red light bulb
• nitrile gloves

Process

• Mix emulsion.
  • Put on gloves for this part.
  • Replace at least one regular bulb with a red bulb.
  • Turn off lights; turn on red bulb.
  • The Speedball catalyst instructions tell you to fill the container 3/4 full with cold water, which is always a tricky thing to gauge because the container is opaque & you can't really see what the water level is, especially in the dark.
  • Put cold water in catalyst jar & mix.
  • Pour catalyst into emulsion & mix thoroughly.
• Coat the screen.
  • Lean the screen at about a 70° to 85° angle against something sturdy. The flat face of the screen should be facing outwards. It's important that both the top and bottom edges of the screen don't shift once the scoop is pressed against it.
  • Pour the emulsion in the scoop, starting at one end and leaving a small amount all down the length of the scoop, in the bottom of the trough.
  • Holding the back of the scoop, touch the edge of the scoop to the bottom of the screen.
  • Tip the scoop up and wait until all of the emulsion has slid down to touch the surface of the screen.
  • As soon as the emulsion has made contact with the screen down the whole length of the scoop, start to gently but firmly pull the scoop up along the surface of the screen.
  • As the scoop approaches the top of the screen, start to tilt it back such that the emulsion will slide back away from the surface of the screen.
  • As the scoop makes contact with the tape at the top of the screen, pull the scoop away from the surface of the screen. Try to do it in such a way that no excess emulsion is left on the screen or the tape.

Exposing screens

Materials

• red bulb
• lamp with ceramic socket
• 250W photoflood bulb
• flat surface
• armature to hang lamp
• transparency
• spray mount
• black paper
• painter's tape
• clean glass
• stop watch
• large sink
• hose
• spray nozzle
• plastic cup
• cardboard scraps
• nitrile gloves
• popsicle sticks
• block out pen supplier Anthem Screen Printing Supply

Process

• Place screen under lamp.
  • Attach lamp to armature and arrange it such that it is the correct height above the horizontal surface.
  • Tape down black paper to flat surface.
  • Turn off lights in the room with the exposing table. Turn on red lamp.
  • Place the screen on the black paper, flat side down.
• Place transparency on screen.
  • Place transparency face down on scrap paper so that the image is backwards.
  • Spray the transparency lightly. Spray it away from everything; spray mount is impossible to clean up.
  • Wait 30-45 seconds.
  • Gently press the image down on the "back" of the screen (the side that gets the ink applied to it). Looking at the back of the screen, the image should read correctly (not be reversed).
  • Place the glass on top of the transparency. Try to arrange it so the edge of the glass lands beyond the area of the screen that has emulsion on it. Otherwise the emulsion under the edge of the glass gets exposed at a different rate from everything else and doesn't clean out neatly.
• Expose the screen.
  • Turn on the lamp and start the timer.
  • After time is up, turn off exposing lamp. It's ok to turn on overhead lights.
• Clean out emulsion from screen.
  • Clean out the screen right away.
  • Gently coat both sides of the screen with water.
  • Go back and apply the highest pressure jet of water possible to the entire surface of emulsion on both sides of the screen. Clean off any bubbles. Continue applying jet of water until the emulsion is washed out of the image on the screen.
  • Gently dry off the screen with a kitchen cloth or paper towel.
• Dry the screen.
  • Let the screen dry thoroughly before doing anything with it.
  • It's fine to have it exposed to light at this point.
• Fill in uncoated areas of the screen.

Printing

Materials

• registration guides suppliers: Anthem Screen Printing Supplies
• painter's tape/masking tape
• ink
• squeegee
• hinge clamps
• paper 150 gsm/92 lb Canford colored paper. Suppiers: Dick Blick
  • NW1: plum
  • NW2: coffee
  • NW3: navy blue
  • NW1-3: black
  • NW4: Forest (I guess. The last batch of forest that I ordered doesn't match the existing NW4 covers exactly)

Process

TK

Exposure times

Speedball emulsion & 250W BBA No.1 Photoflood 500W photoflood (250W takes too long)

Screen Size active area/inside	Lamp Height	Exposure Time
16 x 20"	25.8"	39 min
17 x 23"	28.6"	44 min (!)
17 x 23"	25"	36/37 min

Process so far

I started with 17" from some website. I think I started with 17 min exposure with a 250W bulb, then bumped it up to 35 min, which I'm realizing now wasn't a long enough exposure because with enough spraying the exposed parts of the emulsion were coming out.

Doing even longer exposures didn't seem viable, so I got a 500W bulb.

It seemed like the center of the screens and the edges were behaving differently in terms of washing out the screen, so I tried to figure out what would be the appropriate distance for the bulb. One site says that it should be the same as the diagonal length of the screen (28.6" in this case). I was thinking that if the light spreads in a 90° angle from the bulb, then it should be 1/2 that (Pythagorean theorem).

Starting with 250W/17"/35 min > 500W/17"/17 min > 500W/28"/44 min. 44 min is too long, so I cheated it and tried 500W/25"/35 min. The exposed emulsion washed out.

With the next screen I tried using my calculation for the distance (28.6 / 2 = 14 or 15"). I gave it a couple extra inches, which brought it full circle to 17". The equivalent amount of time would have been 16 min, so I arbitrarily tried adding 6 min for 22 min exposure. Too long, but the image washed out the same towards the edges as in the center, so the height might be fine.

Other notes on exposure

According to the article below with a point light, the height of the lamp should be the diagonal length of the screen.

If a correct exposure time is known, and the lamp needs to be adjusted, the new exposure time can be calculated using the inverse-square law .

The power of the light is equal to the inverse square of its distance from the subject.

E.g. if a light is 1 meter away from the subject, moving it 2 meters away will decrease its power by 1/4. (1 divided by 2 meters * 2 meters)

To determine the new exposure time, (new height/original height)2 * original exposure time.

• Exposing Direct Emulsions (signindustry.com)
  Hints at formulas for determining lamp height and exposure time.

Guides & Resources

• Anthem Screen Printing tutorial videos
• Learn How to Screen Print signindustry.com
• Inverse-Square Law and Lighting tuts+