Screen Printing Quality Control: 20-Point Checklist

A comprehensive quality control checklist is essential for achieving consistent, high-quality screen prints that meet customer expectations. This 20-point checklist covers all aspects of the screen printing process, from artwork preparation to final inspection, ensuring your prints are flawless.

Before Printing:

• Check artwork files for proper format, resolution, color mode, sizing, and text conversion
• Inspect screens for defects, proper tension, and alignment
• Clean screens thoroughly and remove any contaminants
• Mix inks according to manufacturer instructions, checking viscosity and color accuracy

Printing Process:

• Inspect and adjust squeegee condition, position, angle, and pressure
• Prepare substrate by checking quality, positioning, and pre-treating if necessary
• Maintain consistent squeegee pressure, angle, and speed during printing
• Monitor for proper ink deposit, coverage, smudging, bleeding, or misregistration
• Keep the work area clean and free of dust and debris

After Printing:

• Compare printed colors to the approved sample or digital design file
• Inspect each print for defects, uneven coverage, smudging, or curing issues
• Test durability by conducting wash, abrasion, and stretch tests
• Document any issues, root causes, and process adjustments in a quality log
• Review the quality log regularly and implement continuous improvements

Benefits of a Quality Control Checklist:

Benefit	Description
Increased Efficiency	Spotting and fixing issues early saves time and resources
Consistent Quality	Ensures every print job meets the same standards
Customer Satisfaction	High-quality prints lead to happy customers and repeat business
Continuous Improvement	Regularly reviewing quality data helps find and fix recurring problems

By following this comprehensive checklist, you can deliver superior screen printed products, keep your customers satisfied, and continuously improve your workflow over time.

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Before Printing

Check Artwork

Before starting the screen printing process, review the artwork files to ensure they meet the necessary requirements. Here are some key points to check:

1. File Format and Resolution

• Ensure the artwork is in a compatible vector file format (e.g., AI, EPS, PDF).
• For raster images, the resolution should be at least 300 dpi for sharp prints.

2. Color Mode

• Confirm the artwork is set up in the correct color mode (e.g., Pantone or spot colors).
• CMYK or RGB color modes may need additional color separations.

3. Sizing and Alignment

• Check that the artwork dimensions match the desired print size.
• Ensure all elements are properly aligned within the safe printing area to avoid cropping or distortion.

4. Font Conversion

• Convert all text elements to outlines or curves to prevent font substitution issues during printing.

Prepare Screens

Proper screen preparation is key to high-quality prints. Follow these steps:

1. Inspect Screens

• Examine screens for defects like pinholes, tears, or debris.
• Replace or repair any damaged screens.

2. Tension and Registration

• Ensure screens are properly tensioned and aligned for accurate registration between colors.
• Loose or misaligned screens can cause blurry or misaligned prints.

3. Cleaning

• Clean screens thoroughly using a degreaser and scrub brush.
• Remove any residual ink, dust, or contaminants that may interfere with the emulsion coating or printing process.

Mix Inks

Proper ink mixing is crucial for accurate and consistent colors. Follow these steps:

1. Manufacturer Instructions

• Follow the ink manufacturer's instructions for mixing ratios, additives, and curing temperatures.

2. Viscosity Check

• Check the viscosity of the mixed inks to ensure they are within the recommended range.
• Adjust viscosity if necessary by adding thinners or reducers.

3. Test Print

• Perform a test print on a sample substrate to verify color accuracy and opacity.
• Make any necessary adjustments before proceeding with the full print run.

Printing Process

Check Squeegee

1. Inspect Squeegee Condition

   • Look for wear, nicks, or damage.
   • Replace if necessary for smooth ink deposit.

2. Secure Squeegee Position

   • Ensure it is fastened and aligned in the machine.
   • Misalignment can cause uneven pressure.

3. Adjust Squeegee Angle and Pressure

   • Maintain a 60-75 degree angle.
   • Adjust pressure based on substrate and ink type.

Prepare Substrate

1. Inspect Substrate Quality

   • Check for defects, stains, or irregularities.
   • Remove or replace flawed substrates.

2. Position Substrate Correctly

   • Secure the substrate on the printing pallet.
   • Misalignment can cause registration issues.

3. Pre-treat Substrate (if necessary)

   • Apply pre-treatment for certain fabrics.
   • Follow manufacturer instructions for application and curing.

Printing Technique

1. Maintain Consistent Pressure and Angle

   • Apply even pressure and keep the squeegee angle steady.
   • Inconsistent pressure can lead to uneven ink coverage.

2. Check for Proper Ink Deposit and Coverage

   • Ensure ink deposits evenly and covers the stencil.
   • Adjust pressure, angle, or speed as needed.

3. Monitor for Smudging, Bleeding, or Misregistration

   • Regularly check for smudging, ink bleeding, or misregistration.
   • Adjust printing parameters or screen tension if needed.

4. Maintain Cleanliness

   • Keep the work area clean from dust and debris.
   • Regularly clean equipment and work surfaces to maintain print quality.

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After Printing

Color Match

1. Compare printed colors to the approved sample or digital design file. Colors should match consistently across all prints.
2. Lay out a few printed pieces side-by-side under proper lighting. Look for any noticeable color shifts or variations.
3. If colors are inconsistent, adjust ink viscosity, screen tension, or printing parameters to achieve a closer match.

Inspect Print Quality

1. Examine each printed piece for defects such as:
   • Pinholes or missing elements
   • Uneven ink coverage
   • Smudging or ink bleeding
   • Improper curing or adhesion issues
2. Check that the ink has fully cured and adhered to the substrate. Perform a scratch test or tape test to ensure proper curing.
3. If defects are found, identify and address the root cause, whether it's a screen issue, printing technique, or curing problem.

Test Durability

1. Perform a light wash test on a few printed samples to assess durability and color-fastness. Check for fading, cracking, or peeling after washing.
2. Conduct an abrasion test by rubbing the printed area with a rough material or using a standardized abrasion tester. Inspect for ink loss or damage.
3. For printed garments, do a stretch test to ensure the ink can withstand the fabric's natural movement without cracking or flaking.
4. Document the results of these durability tests and make any necessary adjustments to the printing process or ink formulation to improve longevity.

Document Quality Control

Documenting the quality control process helps maintain consistency and identify areas for improvement. Here are some key practices:

Note Issues

1. Log Any Deviations or Defects

   Keep a detailed log of any issues during the printing process, such as:

   • Pinholes or missing elements
   • Uneven ink coverage or smudging
   • Color inconsistencies
   • Improper curing or adhesion problems

   Note the details, potential cause, and steps taken to fix the issue.

2. Document Root Causes

   For each issue, investigate and document the root cause. This could involve:

   • Inspecting screens for defects or tension issues
   • Checking ink viscosity and mixing ratios
   • Evaluating printing techniques or equipment settings
   • Reviewing curing conditions or substrate preparation

Track Adjustments

1. Record Process Adjustments

   Document any changes made to the printing process to address quality issues or improve consistency. This could include:

   • Changes to screen tension or exposure settings
   • Modifications to ink viscosity or mixing ratios
   • Adjustments to printing parameters (e.g., squeegee pressure, speed, angle)
   • Alterations to curing temperatures or dwell times

   Record the specific adjustments, the reason behind them, and the impact on print quality.

2. Note Successful Adjustments

   When an adjustment resolves an issue or improves print quality, note the specific change and the circumstances under which it was effective. This information can be useful for future reference.

Maintain Quality Log

1. Comprehensive Quality Log

   Keep a quality log that consolidates all quality control checks, issues, adjustments, and related notes. This log serves as a central place for tracking and analyzing quality data over time.

2. Regular Log Review

   Regularly review the quality log to identify patterns or recurring issues. This can help pinpoint areas that need further attention or process improvements.

3. Continuous Improvement

   Use insights from the quality log to implement improvements. This could involve refining procedures, investing in new equipment, or providing additional training to operators.

Final Thoughts

Following a quality control checklist is key to getting consistent, high-quality screen prints. By checking each step, from artwork to final inspection, you can catch and fix issues before they affect your products.

Benefits of a Quality Control Checklist

Benefit	Description
Increased Efficiency	Spotting and fixing issues early saves time and resources.
Consistent Quality	Ensures every print job meets the same standards, no matter who does it.
Customer Satisfaction	High-quality prints lead to happy customers and repeat business.
Continuous Improvement	Regularly reviewing quality data helps you find and fix recurring problems.

Using a structured quality control process helps you deliver better products, keeps your customers happy, and improves your workflow over time.

FAQs

How do I check screen printing quality?

To check the quality of your screen printing, follow this checklist:

1. Confirm Digital Design for Printing

Ensure the digital artwork file is print-ready with the correct dimensions, resolution, and colors.

2. Test Print Layout on the Screen

Expose the screen and do a test print to verify the artwork is properly aligned and registered.

3. Ensure Proper Ink Mixing

Mix inks thoroughly to the right viscosity and color according to the job specifications.

4. Perform Test Print on Sample Material

Print on a sample substrate to check for any issues before running the full production.

5. Check for Ink Consistency

Inspect each print for consistent ink coverage, opacity, and no streaking or pinholes.

6. Inspect Alignment of Print

Verify the print is properly centered and aligned on the substrate without skewing.

7. Review Color Accuracy Against Digital Design

Compare the printed colors to the original digital artwork to ensure they match.

8. Approval: Color Accuracy

Once color accuracy is confirmed, proceed with the full production run.

Conducting these quality checks at each stage ensures your screen printed products meet the highest standards.