1. What is Screen Printing Exposure Time?

The exposure time in screen printing refers to the duration required to properly expose a photosensitive emulsion-coated screen to UV light. Correct exposure time is crucial for achieving sharp, durable stencils.

2. How Does the Calculator Work?

The calculator uses the exposure time formula:

Where:

• \( Light\ Intensity \) — Strength of light source (lux)
• \( Distance \) — Distance between light and screen (meters)
• \( Emulsion\ Sensitivity \) — Sensitivity rating of emulsion (lux-seconds)
• \( Power \) — Power of light source (Watts)

Explanation: The equation accounts for the inverse square law of light intensity and the emulsion's specific sensitivity characteristics.

3. Importance of Proper Exposure Time

Details: Correct exposure time ensures proper stencil formation - underexposure leads to weak stencils while overexposure reduces detail. This affects print quality and screen longevity.

4. Using the Calculator

Tips: Enter all values in their respective units. For best results, consult your emulsion manufacturer for exact sensitivity values and perform test exposures to fine-tune.

5. Frequently Asked Questions (FAQ)

Q1: How do I measure light intensity?
A: Use a lux meter at the screen surface position to get accurate readings of your light source's intensity.

Q2: What's a typical emulsion sensitivity value?
A: Most diazo emulsions range between 100-200 lux-seconds, while photopolymer emulsions are typically faster (50-100 lux-seconds).

Q3: Does screen mesh count affect exposure time?
A: Yes, higher mesh counts generally require slightly longer exposure times as less UV light reaches the emulsion.

Q4: Why is distance squared in the formula?
A: This reflects the inverse square law - light intensity decreases with the square of the distance from the source.

Q5: How should I adjust for multiple light sources?
A: For multiple identical lights, calculate each one's contribution separately and use the average exposure time.