So you’ve just gotten your hands on Baselayr Long Lasting Emulsion. It’s perfect for printers who are just starting out, or for those who don’t have a perfect darkroom yet. Now that you have it, how should you use it? How do you get the best out of the emulsion? Screen printing expert Colin Huggins shows you how to mix the diazo into the emulsion, how to coat screens, how to expose, and more.
WHAT IS IT?
Baselayr Long Lasting is a dual cure emulsion. It requires the addition of diazo in order to work. The diazo must be mixed into the the entire base prior to coating a screen and printing.
You can also use less-than-ideal light sources to expose your screens with no problem. Adding diazo means that exposure times will be longer, giving you a bigger window to correctly expose your screen.
PREPARING THE EMULSION
In order to add diazo to the emulsion, you need two things. First, you’ll need distilled water. Leave it out so it’s at room temperature. The next thing you’ll need is a wooden stir stick. Head to your local paint store to pick some up. If you’re mixing quarts, popsicle sticks will be the perfect size.
Fill the bottle of diazo a little more than halfway with the room-temperature, distilled water. Put the lid back on and shake it well. You need to shake the bottle for at least 30 seconds. Once the diazo is dissolved, pour it carefully into the bucket of emulsion. With a stir stick, slowly mix from the bottom up until the diazo is completely combined with the emulsion. It's important to take this process at a slow pace because you want to keep as much air out of the mixture as possible.
Once the diazo and emulsion have been mixed, clean up the bucket and put the lid back on. Set it aside for three hours. Any air that had been introduced into the emulsion needs time to settle out.
COATING A SCREEN
Properly coating a screen means creating a good, even layer of emulsion. You need enough emulsion on top and underneath the threads to create a durable stencil.
In the video, Colin gives the screen a 1x2 coat: two coats of emulsion on the back of the screen, one on the front. This method is ideal for printing plastisol ink. If you’re printing water based ink, a 2x1 coat is best. The higher the mesh count, the less coats you need. Always test your screen’s performance before heading into production.
Coating a screen with new emulsion always includes some guess and check. If the emulsion layer on your screen is too thin, you’ll have trouble getting a detailed stencil. Your screen will also break down on press faster. If your emulsion layer is too thick, you run the risk of underexposing your screen. You’ll also end up laying down a lot more ink on the shirt, which means your flash and cure times will be longer.
DRYING A SCREEN
Even though Baselayr Long Lasting Emulsion is more forgiving than most emulsions, constructing the most optimal darkroom is important. Block out as much white light as you can. Make the room as dry as possible. Having a dry, warm area to dry your screens is necessary. You’ll want a dehumidifier, hygrometer, and some fans to keep the air moving over your screens.
You don’t need a new exposure unit to properly expose screens with Baselayr Long Lasting. It works with pretty much every unit: DIY units, older units, and everything in between.
In the video, Colin tests exposure times using the 21-Step Greyscale Calculator. The emulsion's product page gives approximate exposure times, but your exact time will vary. A solid step seven indicates that your emulsion is fully exposed and will be durable on press. If you can't wash to the seventh mark, the screen is overexposed. If you can wash past the seventh mark, the screen is underexposed. Continue to expose and rinse until you get a better idea of your exact exposure time.
Baselayr Long Lasting is a forgiving emulsion. It’s perfect for printers who are just starting out, or for those who don’t have a perfect darkroom yet. Pick up some Baselayr Long Lasting emulsion and elevate your darkroom.