Top sealing refers specifically to sealing a flexible film directly onto the flange of a rigid tray. This method focuses on reducing material usage while maintaining product visibility and efficient sealing. Tray sealing is a broader category that includes multiple sealing technologies such as standard heat sealing, vacuum sealing, and modified atmosphere packaging. In simple terms, top sealing is one streamlined form within the wider tray sealing system.
The structural difference directly affects packaging performance. Top sealing replaces rigid lids with thin films, which lowers plastic consumption and supports high-speed automated lines. It is widely used for fruits, vegetables, salads, and light fresh products. Tray sealing, especially when combined with vacuum or modified atmosphere technology, is designed to extend shelf life by controlling internal gas composition. According to industry data published by the Flexible Packaging Association, modified atmosphere tray sealing can extend shelf life by 50 percent to 200 percent depending on product type and gas mixture.
From a manufacturing process overview, top sealing emphasizes efficiency and consistency. The process begins with thermoforming trays using PET or RPET materials, followed by product filling and film sealing. The sealing parameters must be tightly controlled to ensure uniform bonding across the tray flange. Tray sealing systems that include vacuum or gas flushing require additional steps such as air extraction and gas injection, increasing equipment complexity and process control requirements.
Process Stage | Top Sealing | Tray Sealing
Material Use | Thin film and rigid tray | Film or rigid lid with tray
Sealing Method | Direct heat sealing | Heat sealing with optional vacuum or MAP
Production Speed | High speed automation | Moderate to high depending on system
Shelf Life Control | Dependent on film barrier | Extended through gas control
Application Focus | Fresh produce and light food | Meat, seafood, ready meals
Material standards used in both systems are critical for food safety and export compliance. PET and RPET are commonly used due to their clarity and recyclability. In the United States, PET materials comply with FDA 21 CFR 177.1630 regulations for food-contact applications. In the European Union, plastic packaging must meet Regulation No 10/2011 requirements. According to Plastics Europe data, RPET can reduce carbon emissions by up to 50 percent compared to virgin PET, making it an increasingly preferred option in sustainable packaging projects.
Quality control checkpoints differ based on the sealing method. For top sealing, the focus is on flange flatness, sealing temperature consistency, and film compatibility. Any deviation can result in weak seals or leakage. For tray sealing systems with vacuum or MAP, additional checks are required, including gas composition accuracy and leak detection. Industry testing methods such as seal strength testing and pressure decay testing are widely used to verify packaging integrity.
Manufacturer vs trader differences play a crucial role in packaging performance. A manufacturer has direct control over mold design, material sourcing, production parameters, and inspection standards. This ensures consistency across large-scale production and allows technical adjustments when needed. A trader may coordinate supply but typically lacks direct control over production, which can lead to variability in sealing performance and structural stability.
Sequoia operates with a manufacturing-focused approach, providing integrated packaging solutions for fresh produce categories. Its product portfolio includes fruit tubs, tomato packaging, salad containers, clamshell packaging, and top seal packaging, enabling consistent quality across related packaging components. This integrated capability supports stable supply and reduces coordination complexity during project execution.
OEM and ODM processes are essential for adapting packaging to specific product requirements. OEM production follows predefined specifications such as tray dimensions, material thickness, and branding elements. ODM development focuses on optimizing packaging structure based on product characteristics, including ventilation design, stacking performance, and sealing compatibility. Sequoia supports both approaches, ensuring packaging solutions align with product type, processing conditions, and market expectations.
Bulk supply considerations extend beyond production capacity. Consistency across batches is critical, especially for automated packaging lines. Factors such as mold durability, raw material stability, and sealing repeatability must be controlled. Top sealing is often preferred for high-volume fresh produce packaging due to its speed and lower material consumption. Tray sealing systems with advanced functions may require more complex process management, which can impact scalability.
A structured project sourcing checklist helps ensure correct decision-making. Key factors include product category, required shelf life, packaging dimensions, material specifications, sealing film compatibility, and equipment matching. It is also important to confirm carton packing methods, labeling requirements, and transportation conditions, especially for cold chain logistics.
Export market compliance must be considered from the beginning of the packaging project. Food-contact materials must meet regulatory standards in the destination market, including migration limits and safety certifications. Documentation such as material declarations and compliance reports should be prepared in advance. Sequoia aligns its production processes and material selection with international standards, supporting smooth entry into global markets.
Top sealing and tray sealing share a common technical foundation but serve different purposes. Top sealing offers a streamlined, cost-efficient solution for fresh produce packaging, while tray sealing provides extended functionality for products requiring longer shelf life. With strong manufacturing control, integrated product range, and export-oriented quality systems, Sequoia delivers packaging solutions that balance efficiency, compliance, and long-term supply stability.
