Emulsion is a chemical that is a crucial part of the screen printing process. It is a light sensitive element that is hardened onto a screen and blocks ink that passes over the screen from getting onto your printed medium. Emulsion not only creates the proper coating that will block the ink so that it is unable to be printed on the material where it isn't needed, but also that it allows for very crisp and clean line work on the medium. The problem with emulsion comes when you are applying the emulsion in order to burn the screen. The emulsion must be evenly distributed and applied correctly, otherwise you risk making the entire printing process a real headache for yourself.
The problem that many screen printers run into is that they are not following the basics when it comes to photo emulsion and cause themselves immense headaches during the printing process, including pin holes and break down of emulsion while printing. While they may think that getting by with how they are coating the screens with emulsion now, creating a better coated screen is much more efficient in the long run, especially on huge orders where deadlines are important and taking the time to create a new screen right in the middle of printing can be catastrophic.
There are several tips that can help you when it comes to creating proper screens with photographic emulsion. First off, ensure that you are using the proper type of screen for the ink you are using and the item that is being printed on. Make sure that the screen you are using is stretched tight, as the tight tension on the screen will allow for betting printing and much greater consistency in printing. You should mix the emulsion at least 2 hours prior to when you are going to coat your screens, as this will give enough time to let air bubbles that may form to bleed out, otherwise you may get pin holes in your screen. If you need to degrease your screen at any point, use a degreaser such as Simple Green or something similar. Before you coat your screen, make sure the screen is completely dry, and then use the sharp edge of the scoop coater to coat the t-shirt facing side of the screen first, and then the side that will be hit with the squeegee. Coat each side with just one coat (some people use multiple coats, but if you follow these steps you should only need one), and then dry your screen t-shirt side down. Once the screen is completely dry you are good to start printing!
There are several resources available online regarding emulsion that can help you understand what exactly the chemical does. Remember, when layering the emulsion you must be in a dark room to prevent any hardening. Good luck!
Gene has been screen printing for over 10 years and has been running his own Fort Lauderdale screen printing shop for a few years now. If you have any questions regarding screen printing custom apparel, such as t-shirts, long sleeves, jerseys, mesh shorts, or totes bags, feel free to contact Gene.
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