I am the screen guy in my shop. All screens, all day, 40+ hrs a week. (I know some might shiver at the thought but I love it)
Here is the life of a typical screen in the shop, from coating to press to reclaim. Note: all shops are different, this is what works at the moment in our shop. Some of the products and conditions I inherited from the former pre-press guys, but most are the way I like to do things.
1) Coating. Right now we use Ulano QTX for most plastisol jobs and QT Discharge for wb and discharge inks. Works for now but I am always looking into other emulsions. QTX coats up nicely with a 1+2 pass with a deep scoop coater. I don't use a rounded edge as it offers little control on finer mesh counts. YMMV.
2) Screens are dried print side down in racks in a warm, clean room with very mild circulating air. (shop vacs and mops are my friends in here, and I use them regularly)
3) Carefully calculated exposures are done with a Olec AL53 and a large wall mounted vacuum frame. Sometimes up to 4 23x31 screens at once.
4) ALL screen exposures are calculated for screen mesh count, color and coating thickness.
5) Exposed screens are placed up to four at a time in a dip tank filled with clear water for soaking. Typically 3-6 minutes depending on stencil thickness.
6) Exposed image areas are washed out from the print side with a pressure washer dialed down to about half pressure and a fine tip 40 degree washer tip. The fine spray helps gently wash out detail areas.
- The pressure washer we use was purchased recently and is my favorite I've used in any shop, the AR 620 with TSS (auto start/stop) It has adjustable pressure up to 1900 PSI at 2 GPM and has a rebuild-able pump. Oil change takes 2 minutes every 200-300 hours of operation.
7) Freshly developed screens are quickly aired off with a compressed air nozzle if needed immediately and set in the sun to dry. (or back in the screen room on rainy days)
Inspected, taped and blocked out screens are sent to the presses.
9) Screens returning from the presses are de-taped and a careful and thorough scraping of excess ink is done on EVERY screen. (the press ops and assistants never, EVER remove enough ink) We try to remove as much ink as possible leaving only a very thin film. Best tool for this: a Hyde 4" joint knife.
10) WB and discharge ink is cleaned from screens immediately. We don't do much wb printing at all, so I usually just use Sprayway 32 to degrade the ink film before cleaning. Plastisol ink film is not typically cleaned from screens before the dip tank, unless it's metallics and shimmers - those screens are treated like they are radioactive and are carefully cleaned cause that sh1t gets everywhere. Screens are sorted to be shelved for later use or reclaimed. We reclaim probably 90% or more of the stencils, but frequently re-ordered designs get shelved.
11) Screens to be reclaimed go into the dip tank four at a time. We use two 37 gallon vertical tanks, one for clear water as mentioned above and one for reclaim. We use Easiway Supra in a 5:1 dilution.
12) I go through screens in the tank in a pull-one/add-one fashion. After adding four screens, waiting about five minutes, I pull the one nearest and add one to the back and go along until done.
13) We have a two-section washout sink, so all the reclaim screens go in one "dirty" side and the other side (which is back-lit) is used only for final rinse and for developing. This keeps the inky stuff isolated from the clean screens and/or new stencils.
14) Screens out of the dip tank get thoroughly pressure washed from the print side to remove all emulsion, and then another slower pass over the image areas to remove most of the ink film. I don't bother spraying both sides yet, it's not required and would be just an extra step at this point - see below...
15) Easiway 701 is applied to the mesh and frame on the print side, and then the mesh and frame on the squeegee side. I use a gong brush or heavy sponge, whichever is on hand.
16) I pressure wash the 701 off starting on the squeegee side that is now facing me (see how that worked? it's all about saving steps). I start in the inside corners first, removing any heavy ink stains or tape goop, and then start from the top down making straight sweeps across the screen. It's very much like spray painting, you cover each pass you make with 50% of your next pass to make sure you are getting even and thorough coverage. Be methodical and hit the entire mesh surface and frame, because you are cleaning everything off, even stuff you can't see. Flip and pressure wash the print side. DO NOT let the 701 dehazer dwell on the mesh long, or it can "set" some ink films and leave a permanent stain. It doesn't work any better leaving it on longer, it works pretty much immediately.
17) Final flood rinse both sides of the frame and mesh until the water sheets off the mesh evenly. Degreaser? Only on finer meshes and not always unless the screen had seem some major action before reclaim. 701 does and excellent job of de-haze and degreasing, as long as it's rinsed well.
Total reclaim time? About 3-5 minutes per screen, give or take depending on the ink mess and age of the stencil.
18) Dry vertically in a clean warm room, handling by the frame sides only. Don't grab the top of the frame after final rinse, especially with gloves because all the muck and contaminants on your gloves (trust me they are not clean) will run into the mesh as the screen dries. Don't stick a fan on the screens unless you are certain only pure filtered air will hit them, or you are inviting dust born pinholes in your stencils.
19) Back to step 1...
