These are mini silkscreen presses that are designed to print four by five inch images and fit in a backpack.
Step 1: Simple Silkscreen Frame
I prefer a wooden frame which can be easily restretched with a staple gun to the metal, made in China frames that are more difficult to rescreen. Simple frames can be made from four identical pieces of lumber. We have used throw away pieces from our local pallet recycler which are easily cut into 1"x1"x6"pieces to make a 4"x6" ID frame. Liberal use of woodglue and 18 GA brad nails will ensure a solid frame. Sandwich the nailed and glued frames between pieces of flat board with a weight while the glue cures.
Step 2: Base and Platen
This step consists of making a base that is big enough to accommodate the screen holding hardware and a raised platen to interface with the screen. For my base I cut a 7" section from a piece of decent plywood
Step 3: Abrasion Step
I used a sandpaper fitted angle grinder, 60 grit sander and 120 grit sander in succession to even out and finish the frames, base , and platen.
Step 4: Coating Step
Pick a way of finishing the newly sanded pieces. I went with wood stain , to which I added some different colors of oil paint. Apply stain with a heavy hand and allow 20 minutes to penetrate the wood, then wipe the excess off with a rag. You could also use paint or oil, anything that will seal and protect the raw wood. I also painted on some polyurethane after the stain was dry.
Step 5: The Screen Holding Clamp and Hinge
This can be approached a few different ways with the simplest being a wooden arm with a slot cut to hold the screen while printing. Alternately, drill a hole in a 2 inch clamp to pivot attached to an angled bracket.
Step 6: Suspension
The suspension holds the screen up off the platen in between prints. I have experimented with just using the tightness of the bolt that attaches the screen holding part to the base to provide suspension, which works okay . Other options include rubber bands and metal springs. My favorite configuration is 2 inch c clamps bolted to angled brackets attached to the base. The metal springs attach via a second hole drilled in each clamp
Step 7: Assembly
Hingeclamp, suspension, and platen are attached to the base with appropriate hardware. Video https://goo.gl/photos/vurhWLUz323KiGHX9
Step 8: Stretching the Screen.
I use sheer polyester mesh from the thrift store for a few bucks. It is usually about the same as 120 -200 mesh depending on the quality of the fabric. Cut a piece about an inch bigger than the frame all around. Wet the screen with water right before you stretch and the finished screen will tighten up as the mesh dries. Start with one side and put a staple into the center and ends , anchoring the mesh. Repeat on the opposite side while pulling the screen taut. Then do the other parallel sides the same way. Next , on the original side , pull the fabric tight and staple in between the first anchors. Go all the way around the framend, pulling and stapling until the screen is secure. I leave no more than about a1/4 inch between staples.
Step 9: Coating the Screen With Emulsion.
Emulsion is the light sensitive material that will make the printable stencil used to print. It must be applied and dried in darkness. While wet, during the act of coating, indirect indoor light is acceptable as the emulsion dries, it must be stored in complete darkness. I use the bathroom outfitted with a fan and space heater for this step . I made a light proof bag from opaque scrim material to store the screens once dry.
Step 10: Exposing the Screen
Different methods of exposing partial areas of the screen to light work to varying degrees. Any opaque object could be used to block exposure and In sunlight the screen becomes fully cured in about 30 seconds. Under a halogen shop light suspended 10 inches above the screen exposure takes 4-10 minutes. Get a cheap timer and experiment with exposure times. Laser printed Clear adhesive film available from cheapo print shops will give razor sharp exposures with minimal fuss. In a pinch parchment or butcher or tracing paper can be made translucent with a liberal application of baby oil.
Step 11: Rinse the Exposed Screen.
Take the screen directly from the exposure to area to a dimly lit area to rinse. A short hose and nozzle attached to sink or shower faucet works fine. First wet both sides and allow a couple minutes for the unexposed emulsion to loosen. Carefully spray away the uncured emulsion with cold water.