Coating The Screen ( Direct Emulsion )

Step 1 – Place a piece of wood or 2 x 4 against a wall (I use my closet door). Make sure  you are coating the screens in a light safe area (using yellow bulbs) or at least in a dark room away from direct sunlight. I always use newspaper to cover the general area as emulsion can get really messy.

Step 2 – Prop the screen frame up against the the piece of wood so it is stable. You will be applying pressure with the scoop coater and you do not want it to slip during the process. Also, make sure you have properly degreased and dried the screen.

Step 3 – This is another angle of the set up. Get your scoop coater ready once you open the emulsion.

Step 4 – Pour the emulsion into the scoop coater. Don’t worry about pouring too much in there because you can always pour unused emulsion back into the container when finished.

Step 5 – Most scoop coaters have a thin and thick edge. Make sure the sharper (thinner) edge of the scoop coater is facing the screen. Tilt the scoop coater flat against the screen across the mesh until the emulsion contacts the screen.

Step 6 – With an even motion, slide the scoop coater up the screen to deposit a thin layer of emulsion. Remember to keep it flat against the screen until you reach the top. As you start to reach the top, tilt the scoop coater away from the screen.

Step 7 – Depending on the type of emulsion you use, you may need to coat the inside of the screen frame as well. I always do one coat on both sides.

Step 8 - Typically, the sides will have thicker drips of emulsion. I will use a small piece of card stock to even out the edges. After this step place the coated screen in a well-ventilated, dust free area that is completely dark (no light at all!). Make sure to lay the screen horizontally to promote even thickness as the emulsion dries. To speed up the drying process you can use a fan.

Step 9 - Pour any remaining emulsion back into the bucket and close the container. Clean it all up and wait for the screen(s) to dry!
The first step in the process of screen printing is the creation of the film positive. A film positive is artwork (text and/or images) on a transparent or translucent material. For best results the artwork must be opaque enough to block light from exposing the emulsion during the screen exposure process.
There are many ways to create the film positive but the easiest way is to load transparency film into your laser or ink-jet printer (be sure to select the correct type for your printer type) and then print your design (in black) onto the transparency film.
For best results, the printed artwork should not allow any light to pass through. If you notice that you can still see light through the transparency, one trick is to use an opaque black pen to fill any remaining areas. The other trick is to double up the transparency film (i.e. print 2 or even three copies of the design and stack them together). Make sure you tape them together (with clear tape) to ensure that they don’t move around during the exposure process.
Also, for complicated designs where registration needs to be perfect, make sure to print registration marks on each color separation as well. Typically, 3 marks are placed outside of the artwork area. The marks consists of a circle with a cross in the middle. I usually just tape over these during the printing process to block ink from coming through.
Vellum can also be used to print your design. Vellum is not completely transparent but will allow enough light to pass through to expose the screen properly. A good rule of thumb is to increase exposure time by 20% when using vellum.
Another technique is to draw your artwork directly onto the transparency film using india ink. You can also draw onto a white piece of paper and go to Kinko’s or Staples and have them print onto transparency film for you.

Step 1 - Either scan or create your artwork on your computer. Make sure that you set all your artwork to print as black as possible! If you printing multiple colors for your print, each color needs to be printed separately in black.

Step 2 - Transparency film can be purchased at Staples or Office Depot. Make sure that it is the correct type for your printer. I use 3M Transparency film with great results.

Step 3 - Warm up your printer and be sure to print your transparencies during the same time frame. There may be some shrinkage on transparencies due to the heat so it’s best to print them at the same time for consistency. There is also specialty transparency that does not shrink but I have never needed to use it so far.

Step 4 - After printing has occurred, hold the transparency against a light to see if the artwork is completely opaque. This is very important. If light can pass through the art work, it can lead to poor results during the exposure process.

Step 5 - In this example I have doubled up the transparencies in order to get the artwork completely opaque. The above example shows blue painter’s tape for illustration purposes but the ideal tape to use is doublesided sticky tape to align the transparencies.

Step 6 - Here’s the final artwork, ready to be burned onto a screen!

Exposing The Screen

Step 1 -  In light-safe conditions, p lace your film positive(s) right side up onto the glass of  your exposure unit. The film positives should appear exactly as you intend them to be printed (not reversed). I tend to place my artwork directly in the middle and away for the very edges of the exposure unit.

Step 2 – Place your coated screen (completely dry) print side down onto the film positives. Be sure to center the film positives, leaving at least 2-3 inches of room around the designs. Next, place a piece of foam (cut to the inside dimensions of the screen frame) inside the screen frame. If you want to be extra careful about light diffusion, you can fit a black t-shirt over the foam before placing it into the screen. The film positive should be in between the glass and the screen mesh after this step.

Step 3 - On top of this, add some weighted books or anything that will distribute a even amount of pressure and ensure that the artwork and emulsion have great contact with the glass.

Step 4 - Turn off all other lights and then turn on the exposure unit (or if it has a built in timer, set it to the correct amount). Depending on your emulsion type, mesh count, UV tube wattage and artwork, exposure times may vary. You may have to do this step a few times to determine the exact exposure time.

Step 5 – After the screen has been exposed, quickly move to the washout area. Use a garden hose and cold water to spray both sides of the screen (this stops the chemical reaction). Continue spraying the screen with water with medium pressure. After some time you will notice the screen starting to “open up”. Once this happens use the hose to gently spray the design areas. Do not stop until all the areas have opened up completely. Do not use a pressure washer to do this step as it may actually remove parts of the emulsion that make up your design.

Step 6 – Throughout the process, hold up the screen to a light in order to see if the screen still has bits of emulsion that still need to be removed. Once you are satisfied you can leave the screen to dry. Also, for thinner lines and detailed work, you may need to be very gentle with the washout process and may actually require less exposure time. In these instances, I would consider drying the screen and then re-exposing to “harden” the emulsion.

Step 7 – Ready to be taped!