Detecting Pinholes
- Visual Inspection:
- Hold the screen up to a light source and look for tiny spots of light. Move the screen at different angles.
Causes and Solutions
Contaminated Screens:
- Cause: Dust, oil, grease, or dirty glass
- Solution: Clean thoroughly, ensure dryness, avoid touching with bare hands, store properly.
Emulsion:
- Cause: Uneven or thin application, air bubbles, expired/sensitized emulsion, cold storage, dirty scoop coater, metal utensils.
- Solution: Apply evenly, slow coating, check expiration, warm to room temperature, clean scoop coater, use wooden stirrer.
Incorrect Exposure:
- Cause: Underexposure.
- Solution: Use exposure calculator, step wedge test, ensure even light.
Environmental Factors:
- Cause: High humidity, temperature fluctuations.
- Solution: Control environment.
Screen Tension:
- Cause: Low/inconsistent tension.
- Solution: Regularly check and adjust.
Inadequate Drying:
- Cause: Incomplete drying, dusty environment.
- Solution: Ensure complete drying, clean environment.
Poor Handling:
- Cause: Rough handling, bare hands.
- Solution: Handle gently, use gloves.
Degreasing:
- Cause: Improper degreasing.
- Solution: Use dedicated degreasers.
Drying Screens:
- Cause: Dusty environment.
- Solution: Dry horizontally in dust-free area.
Post Exposure Hardening (Water-Based Inks):
- Cause: Emulsion breakdown.
- Solution: Ensure correct emulsion, use hardener if needed.
By understanding these causes and implementing solutions, minimize pinholes in your screen printing process.
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