Figuring out exposure times is one of the most difficult tasks in screen printing. Questions about exposing appear every day in Facebook screen printing groups like Rogue Printers, in our DMs, and calls in to our experts. If you're struggling, you're not alone. The best thing you can do is invest in a 21-Step Exposure Calculator. How does it work? Let's dive in.
First thing to note is that you're not going to use the same time for all screens. The following factors will affect how long or short you need to adjust the exposure time:
- Type of emulsion
- Type of exposure unit
- Mesh count
- Mesh color
- Film density
- Humidity levels in darkroom
- Time screens have dried
- Level of detail in design
- Thin thread vs. standard thread
Lots of factors can affect what the time may be. It's important that with every new design, emulsion, mesh, etc., that you test the screen with the exposure calculator to ensure it's properly exposed.
HOW TO USE THE 21-STEP EXPOSURE CALCULATOR
It's pretty simple. Place the calculator on the screen, away from the design. Expose the screen.
Wondering how to even pick a time to start? If you're using an emulsion from Ryonet, the product page of each emulsion shares a starting time depending on the exposure unit you're using. Remember, it's a starting point. Depending on the other factors mentioned before, you will have to adjust the time to find the perfect time for exposing that particular screen.
Once the screen has been exposed, bring it to the washout booth. Soak the screen in water in a dip tank or gently rinse it with a hose and let the water soak into it before using a pressure washer. Rinse the screen, and take a look at the calculator.
The lucky number you want to hit is seven. If you've hit the seventh mark, it means you're screen is perfectly exposed! If you can wash out past the seventh mark, the screen is under-exposed. If it stops washing out before the seventh mark, the screen is over-exposed.
Off by a few steps? No worries. The exposure calculator has a handy table that shares how you should adjust your time based off what step you had reached. Grab a new screen, make the time adjustments, expose, and bring it back to the washout booth.
LEARN MORE ABOUT MAKING SCREENS
That's all there is to it! The 21-Step Exposure Calculator is an inexpensive tool that helps printers dial in their exposure times much faster without the headache and frustration.