Pressure Sensitive Seals Cap Liners, 31 mm

Sealing liners for jars, pressure-sensitive, 31 mm

Self-adhesive sealing liners seal the jar so that customers can immediately tell whether it has been opened before. They are placed inside the lid, and upon first tightening, they adhere to the jar neck. Their primary purpose is tamper evidence, while also reducing content leakage and drying out during storage and transport. The finished product therefore appears more trustworthy.

The liners are supplied separately and are compatible with lids and jars with the same neck diameter as stated in the specifications of the respective jar. They are intended for packaging cosmetics: creams, butters, balms, scrubs, and loose products in smaller jars.

Key benefits

• Tamper evidence – after first opening, the liner remains adhered to the jar neck and the customer must peel it off. It is clear that the product has not been opened before.
• Easy application without equipment – the liner works on the principle of a pressure-sensitive adhesive, requiring no induction sealing device or heat. Simply insert it into the lid and tighten the lid securely.
• Protection against leakage and drying out – the liner complements the lid seal and restricts air access to the contents. This is particularly useful for creams and balms that change texture when exposed to air.
• Clean appearance – the white liner does not visually burden the packaging and leaves no significant mark on the neck after peeling.
• Suitable for small batches – for home and small-scale professional production, this is the most accessible way to achieve a tamper-evident seal without investing in machinery.

How to use the liners

The liner has one adhesive side and one smooth side. The adhesive side must face towards the jar neck, and the smooth side rests against the inner surface of the lid. Place the liner into the lid, fit the lid onto the filled jar, and tighten. The pressure of the thread presses the adhesive against the neck and the liner adheres to it. When unscrewing for the first time, the lid comes off, the liner stays on the jar, and the customer peels it off by the edge.

For reliable adhesion, the jar neck must be clean and dry. Residues of cream, oil, or dust on the neck will weaken the bond. Check the filled jar before closing and wipe the neck if necessary. Do not touch the adhesive side of the liner — finger grease reduces adhesion.

What contents are they suitable for

The liners are best suited for jars containing creams, butters, balms, thick gels, scrubs, bath salts, and loose products — contents that do not flow or leak through the neck. The liner adhesive is not designed for hermetic sealing of thin liquids. For liquid oils, thin emulsions, or products with a high content of alcohol or essential oils, we recommend verifying the liner's adhesion and sealing on a test sample with the specific formulation. Oily and alcohol-based components may affect the adhesive layer.

The liner is made of polyethylene and is intended for contact with cosmetic preparations. Suitability for food contact is not declared.

Good to know

• The diameter must match. The 31 mm liner is intended for lids and jars with a corresponding neck diameter. If the neck is too large, the liner will not adhere around its entire circumference; if too small, it will buckle inside the lid and will not seal properly. The neck diameter of the jar is stated in its specifications.
• Smooth neck edge. Best adhesion is achieved on a flat, smooth edge. For jars with a narrow or rounded edge, we recommend testing on a single unit first.
• Single use. Once peeled off the neck, the liner no longer holds. A new liner must be used each time the jar is refilled.
• Temperature during filling. If filling balms or butters while warm, allow the contents to cool and set before closing. Warm contents and steam on the neck impair adhesion and the liner may detach from the neck.

Frequently asked questions