How to Match Glassine Caliper to Your Coating Process？

Created on 07.23

Matching glassine caliper (thickness) to your coating process is critical for achieving consistent quality, efficient production, and minimizing waste. Here's a breakdown of the key factors and how to approach it:

1. Understand the Core Relationship:

Glassine Caliper = Foundation: It determines the paper's strength, stiffness, porosity, surface smoothness, dimensional stability, and heat transfer characteristics.
Coating Process = Application & Transformation: This involves applying a liquid (adhesive, barrier, release, functional coating) and then drying/curing/solidifying it under specific conditions (heat, air flow, time, tension).

The goal is to select a glassine caliper that:

✅  Handles process tensions without breaking or excessive stretch.

✅  Allows uniform coating application at target weight/thickness.

✅  Transfers heat effectively during drying without damage (scorching, curling).

✅  Minimizes defects (pinholes, cockle, curl, blocking).

✅  Meets the final product performance requirements.

Key Factors to Consider When Matching Caliper:

1. Coating Type & Properties:

2. Coating Application Method:

3. Drying/Curing Conditions:

4. Web Handling & Tension Control:

5. Final Product Requirements:

How to Select & Optimize the Caliper:

1. Define Requirements: Clearly outline coating type, target weight, application method, drying conditions (max temp, time), line speed, max tension, and final product specs (thickness, stiffness, performance).

2. Consult Suppliers: Engage your glassine suppliers early. Provide your process details and ask for recommendations on caliper grades and tolerances. They have extensive experience.

3. Bench/Pilot Testing:  If possible, test different calipers on a small scale or pilot coater. Evaluate:

4. Production Trials:  Run carefully controlled trials on the production line with different calipers. Monitor:

5. Measure & Analyze: Rigorously measure key parameters during trials: incoming caliper profile, coating weight profile, moisture, temperatures, tensions, final caliper, curl, roll hardness.

6. Optimize Process Settings: The "best" caliper might require slight adjustments to tension profiles, oven settings, or coating application parameters. Finding the right caliper and its optimal process window is key.

7. Prioritize Consistency: Once the optimal caliper is chosen, work with your supplier to ensure consistent caliper within tight tolerances across the roll and from roll to roll. Variability is the enemy.

Common Pitfalls:

Too Thin: Web breaks, excessive stretch, poor tracking, coating penetration/pinholes, handling damage, curl, winding problems.
Too Thick: Reduced roll yield (less linear meters per roll), higher material cost, potential drying issues (under-cured coating), excessive roll hardness, reduced flexibility if needed, potentially higher tension requirements.
Inconsistent Caliper: Coating weight variations, streaks, drying inconsistencies, curl variations, winding defects.

Conclusion:

Matching glassine caliper to your coating process is not a one-size-fits-all solution. It requires a systematic analysis of the coating properties, application method, drying conditions, web handling requirements, and final product needs. Collaboration with your glassine supplier, thorough testing (pilot and production), rigorous measurement, and a focus on incoming caliper consistency are essential for success. Investing time upfront to find the optimal caliper will pay dividends in production efficiency, quality, and reduced waste.

Ray

Ferrill

Evelyn