For premium brands using glass containers, the sealing liner is the final and most crucial component of the packaging system. Glass is favored for its chemical inertness and luxury feel, but it presents unique challenges for hermetic sealing. A high-performance liner is essential to bridge the gap between the rigid glass rim and the metal cap, ensuring a leak-proof and airtight environment. This protection is vital for preventing the oxidation of active ingredients in high-end cosmetics and maintaining the sterility of pharmaceutical preparations. At Uniseel, we engineered our glass-specific liners to provide a 'Unified Quality' that ensures every bottle is 'Sealed for Safety' from the production line to the global market.
Beyond basic sealing, the liner provides a critical layer of tamper-evidency. For the pharmaceutical and nutraceutical industries in the USA and Europe, a visible seal is a mandatory trust signal. Our liners are designed to withstand the varying thermal expansion rates of glass and metal, ensuring the seal remains intact during long-distance shipping and shelf storage.
Choosing the correct liner type depends on your content's chemistry, your production capacity, and your target market's requirements.
IHS Liner (Induction Heat Seal): High-Security Hermetic Sealing
The Induction Heat Seal (IHS) liner for glass is a specialized multi-layer structure. Unlike liners for plastic, these are chemically formulated with a dedicated polymer layer that bonds specifically to the glass surface when activated by an induction sealing machine.
• Features: Requires an induction sealing machine. The electromagnetic current heats the foil, melting the coating to create a permanent, airtight bond to the glass rim.
• Benefits: Provides a 100% moisture-proof barrier and definitive tamper-evidency. Ideal for pharmaceuticals and high-purity food products.
Pressure Sensitive Liner (PS): Efficient & Machine-Free
The Pressure Sensitive (PS) liner is a foam disc coated with torque-activated adhesive. It does not require any specialized machinery to apply.
• Features: The seal is formed by the pressure applied when the cap is tightened. The adhesive bonds the liner to the glass rim automatically.
• Benefits: Cost-effective for small-to-medium batches. Commonly used for dry goods like capsules, vitamins, and powders.
PE/EPE Foam Liner: Resilient & Multi-Use
The Expanded Polyethylene (EPE) foam liner is the standard for general-purpose sealing.
• Features: A white, elastic foam disc that compresses to form a physical seal. It remains in the cap after opening.
• Benefits: Reusable, chemical-resistant, and provides excellent buffering. Standard for liquid cosmetics and household products.
PS22 Liner: The Precision Standard
PS22 is a specific grade of high-performance pressure-sensitive liner. It is optimized for wide-mouth containers, ensuring a consistent and secure seal even on larger diameters like 70mm and 89mm glass jars.
At Uniseel, our commitment to safety is absolute. Our core liner products, including the specialized IHS for Glass and our Pressure Sensitive (PS) range, are fully backed by SGS testing reports. Furthermore, all liners are produced in our ISO Class 7 Cleanroom to eliminate microbial and particulate risks.
Our History: Over 30 Years of Packaging Expertise
Hangzhou Uniseel Technology Co., Ltd. is the specialized foreign-trade subsidiary of Hangzhou Lin'an Shengxiang Technology Co., Ltd. With over thirty years of deep-rooted expertise in cap manufacturing since the 1990s, we have established ourselves as a trusted global leader in precision sealing solutions.
R&D Excellence and Quality Assurance
Equipped with advanced production facilities and an ISO Class 7 (Class 10,000) cleanroom, we hold dozens of patented technologies. Our ISO9001 certified quality management system ensures every product meets pharmaceutical-grade standards.
Our Corporate Slogan: Unified Quality, Sealed for Safety.
At Uniseel, we believe a cap is the final guardian of your product's integrity. Our mission is to provide global brands with reliable, aesthetically superior, and legally compliant sealing solutions that protect consumer health and elevate brand value.
Q1: Is an induction liner for PET different from an induction liner for Glass?
A1: Yes. The sealing layer (the polymer that melts) is different. PET liners will not bond correctly to glass, and glass-specific IHS liners are required for a permanent hermetic seal.
Q2: Do PS liners provide a waterproof seal for glass bottles?
A2: PS liners are excellent for keeping dry goods fresh, but for liquid products in glass bottles, we always recommend IHS (Induction) liners for a 100% leak-proof and hermetic result.
Q3: How do I ensure a perfect seal on a glass jar?
A3: Ensure the glass rim is clean and free of oil or powder. For IHS, the sealing machine power and speed must be calibrated to the specific bottle and cap size. We provide ± 0.1mm tolerance liners to ensure the perfect fit.
Q4: Are your foam liners suitable for oils?
A4: Our EPE foam liners have excellent chemical resistance, but for essential oils or aggressive chemicals, we recommend our specialized foil-faced foam liners for maximum protection.
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