Troubleshooting Screen Printing Emulsion Problems: A Comprehensive Guide

Screen printing can be a rewarding but sometimes challenging endeavor, especially when issues arise during the exposure process. One common problem encountered is the emulsion washing off after burning, which can ruin the design. This guide will address common causes and solutions for this issue, providing detailed steps to ensure successful screen printing.

Identifying the Problem

When the emulsion washes off around the burned area, it is often due to underexposure or improper screen preparation. Ensuring your screens are properly prepared and exposed is crucial for achieving high-quality prints.

Common Causes and Solutions

Underexposure

Underexposure is a frequent cause of emulsion washing off. If the screen is not exposed to light for a sufficient duration, the emulsion will not harden properly, leading to it washing away during the rinse.

Solution: Adjust Exposure Time

1. Evaluate Your Light Source: If you are using a 1500-watt light, the distance and duration are critical. Typically, a 1500-watt light should be placed about 16 inches above the screen.
2. Increase Exposure Time: Based on experience, a 1500-watt light requires an exposure time of around 12 to 14 minutes to ensure proper hardening of the emulsion. Adjust your exposure time accordingly, and test incrementally to find the optimal duration.

Screen Preparation

Proper screen preparation is essential. If the screen is not properly degreased before applying the emulsion, contaminants can prevent the emulsion from adhering correctly.

Solution: Degrease the Screens

1. Use a Degreaser: Before coating your screen with emulsion, clean it thoroughly with a degreaser. Simple Green and a soft scrub can be effective.
2. Rinse Clean: After degreasing, rinse the screen thoroughly to remove any remaining residues. Allow the screen to dry completely before applying the emulsion.

Equipment Recommendations

While adjusting exposure time and ensuring proper screen preparation can significantly improve your results, investing in specialized equipment can also enhance your screen printing process.

Invest in a UV Exposure Unit

1. Benefits: A UV exposure unit is designed to provide consistent and precise exposure, reducing the variability that can occur with different light sources. This consistency can save time and reduce waste.
2. Options: For a small shop, consider an Aluminum UV Exposure Unit (20"x24"). For larger operations, an Automated UV Exposure Unit (25"x36") might be more suitable. Though the initial investment is around $400, the time saved and the improved quality make it worthwhile.

Practical Tips from Experienced Printers

Experienced screen printers have shared valuable insights based on their own trials and errors:

1. Light Distance and Duration: For a 1500-watt light, placing it about 16 inches away and burning for 12 to 14 minutes has been effective.
2. Patience and Testing: Adjusting exposure times incrementally and testing on a small scale before full production can help fine-tune the process.

Conclusion

Proper exposure and screen preparation are essential for successful screen printing. By addressing underexposure, ensuring thorough screen cleaning, and considering an investment in a UV exposure unit, you can achieve consistent and high-quality results.

For more detailed tutorials and tips, follow our YouTube Channel and stay updated with our tech blog. If you're local to Greensboro, North Carolina, visit us for hands-on assistance and demonstrations. Happy printing!