The Hidden Link Between Resin Unloading and Product Quality

When processors encounter “angel hair,” “snakeskin” or “dust” in their material stream, it’s often mistakenly assumed that the issue originated at the source. However, in many cases, the issue starts closer to home: right at the unloading site. Despite receiving resins manufactured to rigorous quality standards and delivered in clean, sealed containers, improper unloading practices can damage pellets and compromise product performance before they ever enter the production line.

This article explores the critical role of resin unloading and best practices for protecting product quality, reducing downtime and preventing costly contamination.

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The Real Culprit Behind Common Resin Defects

Processors are often surprised to learn that common defects are rarely a reflection of poor resin quality at the point of manufacturing. Instead, they frequently result from what happens during the final transfer into silos or processing equipment.

• Angel hair: Thin resin streamers created when pellets experience excessive heat, friction or air velocity during unloading.
• Snakeskin: Thin, textured resin layers formed inside transfer lines by repeated smearing and softening, which later break off and cause clogs.
• Dust: Microscopic particles generated when pellets abrade against each other or the interior of transfer hoses.

When any of these are introduced into a system, the results can be costly and cause issues such as blocked filters, fouled sensors, inconsistent material flow and unplanned shutdowns.

Unloading as a Critical Control Point

What may seem like an operational formality — connecting hoses, adjusting air pressure and initiating flow — is actually a critical quality control point. Improper unloading practices, particularly those involving excessive air velocity, overheated lines or poor hose setup, can create the perfect storm for material degradation.

Careful material handling can prevent pellet damage and product performance issues. Source: Shell Polymers

Implement the following best practices to minimize friction, static and heat during unloading:

• Keep airflow in check: Maximum air velocity should not exceed 4,600 feet per minute in vacuum systems or 4,200 feet per minute in pressure systems.
• Use grounded, clean and, ideally, stainless steel hoses: This minimizes static buildup and internal abrasion. While aluminum and plastic are acceptable, they are more prone to static charge buildup and internal wear. Stainless steel hoses, especially when appropriately grounded, reduce this risk dramatically.
• Minimize hose bends and length: Curves and extra hose length can increase turbulence, a major contributor to fines and streamers. Wherever possible, hoses should be suspended off the ground and arranged with minimal curvature, ensuring a smooth flow path for the resin.
• Ensure proper grounding and inspect all equipment before use: Ensure that caps are sealed, spills are contained, and hoses are dry and debris-free.
• Unload during cooler parts of the day: Especially in warmer climates, scheduling transfers during cooler hours such as early morning and avoiding sun-exposed metal pipes can reduce heat-related pellet softening.

In addition to these best practices, maintaining clean transfer systems is as important as proper technique. Cross-contamination, either from residual product in lines or poorly cleaned railcars, is a leading source of pellet degradation and product variability.

The Role of Training and Shared Responsibility

Even the best equipment and cleanest trucks can’t prevent quality loss if those unloading are not equipped with the proper tools and knowledge. To minimize common mistakes during resin transfer, processors should consider investing in:

• Regular training on safe unloading procedures
• Airflow monitoring protocols
• Operational decision-making authority, enabling employees to halt operations if any issues arise

Maintaining resin quality is a shared responsibility, and it's essential for all personnel involved in unloading resin to follow best practices and act proactively when issues arise. This is where collaboration with your supplier becomes critical. Shell Polymers works closely with customers to provide technical guidance, share unloading best practices and assist in real-time incident response through a 24/7 CHEMTREC hotline. We also encourage our customers to align with Operation Clean Sweep principles, an industry-led initiative to reduce pellet loss and uphold material integrity throughout the supply chain.

A Simple Fix to a Costly Problem

While issues like dust, angel hair and snakeskin are common pain points in resin processing, they are not inevitable and highlight a critical opportunity for operational improvement. By implementing disciplined unloading practices, maintaining clean and properly configured transfer systems, and ensuring that personnel are trained and equipped to monitor material flow, companies can help reduce the risk of downstream contamination and equipment failure.

Treating resin unloading as a strategic quality control point rather than a procedural task can help ensure that materials perform as intended across their entire lifecycle. When quality is preserved from delivery through processing, the benefits extend well beyond a single facility. Reduced production downtime, improved product consistency and fewer material-related defects contribute to a more efficient, reliable and sustainable value chain for everyone from resin producers and converters to brand owners and end users.

ABOUT THE AUTHOR: Shaun Pirtle has 39 years of technical service and product development experience in the polyolefins industry, with the last seven years at Shell Polymers, where he is currently a senior technical service engineer. Pirtle has worked extensively on blown and cast film technology development projects from inception to commercialization, most of which were focused on industrial, consumer and food packaging. He also has focused significantly on the extrusion/fabrication of new applications and resins. Direct questions to info@polymers.shell.com.