Coat again (you shouldn't have to wash the screen again if you do this straight away), this time more slowly. There are blank spaces left without emulsion - there is either not enough emulsion in the trough, or you didn't wait long enough for the emulsion to be touching the mesh all the way along the trough before dragging it up the screen. Your coat is too thick - use the trough (without tipping it) to scrape up the screen to remove any thick areas of emulsion. It is good practice to put some wedges (blocks) under the frame to allow the air to circulate. It's important to keep it clean, especially the edge that touches the mesh: any mark on this edge can ruin an even coating of emulsion next time.ĭry the screen horizontally, printing side up somewhere dark. Store the emulsion in the fridge for up to 6 months. The rest of the emulsion can be scraped back into the pot. You can do this on both the inside and the outside of the mesh to ensure an even coat. This will scrape away any uneven or thick areas of emulsion on the screen, particularly any thick edges. Next, place the screen upright and use the trough to drag up the screen (without tipping it this time). This allows the trough to catch the excess emulsion. To avoid drips at the top of the screen, slightly tip the screen towards the trough, maintaining contact between the trough and the mesh. Tip the trough a little steeper and gently drag it up the mesh until you get to the top. Tip the trough until the emulsion reaches the mesh all the way along. Start the trough at the bottom of the screen, slightly higher than where the frame ends. Make sure your fingers are not wrapped too far around the bottom of the trough or they can drag marks up the screen. We want to coat the flat side of the mesh, where it is flush with the frame. Hold the screen in one hand and the trough in the other.
#Emulsion time for 20x24 screen 160 mesh speedball emulsion how to
You can watch a video about how to coat a screen here, or read on for instructions.įirst, half-fill the coating trough with pre-mixed photo emulsion. 225mm troughs are perfect for our A4 screens, 315mm troughs for our A3 screens etc. You will need a trough that is slightly narrower than the width of the mesh on the screen. The aim of coating screens is to fill all of the holes in the weave of the mesh, not to deposit a couple of mm on top of the mesh. To coat your screen, use a coating trough. You can watch a video showing how to mix up your emulsion here. It needs to be thoroughly mixed with water in the bottle before it is added to the emulsion. The sensitiser is in powder or gel form in a tiny quantity in the bottle. Photo emulsion is made from two parts: the emulsion itself and sensitiser. If you are using new emulsion, it is best to mix it an hour or so in advance so that all the bubbles can disperse. We would advise coating the screens in a room with subdued lighting – no need for a safe light but subdued light does allow you a little more time to coat your screen.
Make sure you wash the cleaner thoroughly off the screens and then leave the screen to dry fully. The best products we have found for cleaning screens prior to coating is Speedball Speed Clean. This should remove any trace of grease. To start with you must ensure that your screen is clean and dry, any grease (even from fingers) can cause problems with the emulsion adhering correctly. A successful Photo Emulsion Stencil will depend on many things: the wattage of the lamp, the timings, the distance from the screen and the thickness of the emulsion.
We are often asked for guidance with screen printing and the most common request is for help with exposing screens.īenjamin Franklin is quoted as saying “By failing to prepare, you are preparing to fail” – I don’t know how good he was at screen printing but it sounds like he had some experience! One of the most common problems is, when using a new light source, to assume the exposure times will be the same as the guidance/previous lamps.
Squeegees, Scoop Coaters and Hinge Clamps.
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