Master your darkroom with our free screen printing exposure calculator online. Learn to calibrate UV LED and Halogen burn times using the inverse square law.
Screen Printing Exposure Calculator
Calibrate your emulsion burn times
What is an Exposure Calculator?
An exposure calculator screen printing tool is a mathematical utility used to determine the exact amount of time a light source needs to harden (cross-link) photo-sensitive emulsion.
While many people use a physical “step wedge” test strip to find their base time, our screen printing exposure calculator online takes it a step further. It uses the Inverse Square Law, which states that if you double the distance between your light and your screen, the light intensity doesn’t just drop by half—it drops by four times.
How to Use the Calculator
To get the most out of this tool, follow these three steps:
- Establish a Base Time: Perform a “Step Wedge Test” at a fixed height (e.g., 12 inches) until you find the time that produces a perfect, hard stencil.
- Input Your Data: Enter that “Base Time” and “Base Distance” into the calculator.
- Adjust for New Projects: If you have a larger screen and need to move your light higher to cover the whole mesh, enter the “New Lamp Distance.” The calculator will provide the new, corrected burn time.
Also see: 3D Printing Price Calculator
FAQs
How long is 50W LED exposure time?
For a standard 50W UV LED lamp positioned 12 inches away from the screen, exposure times typically range between 45 and 90 seconds for dual-cure emulsions. However, this varies based on the emulsion brand and mesh count. Always use our exposure calculator screen printing tool if you move the lamp higher for larger frames.
What are common mistakes in screen-printing?
- Improper Degreasing: Not cleaning the mesh properly leads to “fish-eyes” (holes) in the emulsion.
- Poor Film Positive Density: If your black ink on the transparency isn’t “light-proof,” UV rays will leak through and partially cook the emulsion where it should stay soft.
- Drying in Humidity: Emulsion must be 100% dry before exposure. If the room is humid, the emulsion remains “tacky” and won’t cross-link correctly.
What is the best halftone size for screen-printing?
For most manual printers in Kenya using 90T to 120T mesh, 45 to 55 LPI (Lines Per Inch) is the “sweet spot.” If you go higher (e.g., 65 LPI), the dots become so small that they may not resolve correctly unless your exposure timing is perfectly calibrated using an exposure calculator.
Conclusion
Consistency is the secret to a profitable printing business. By moving away from “guessing” and utilizing our screen printing exposure calculator online, you reduce waste, save emulsion, and deliver sharper prints to your clients.
