Pressure-sensitive sealing liners for jars, 38.4 mm

These are pressure-sensitive sealing liners for lids of jars and containers with a neck diameter of 38.4 mm. Their purpose is to seal the contents immediately after filling so that nothing leaks or dries out during transport and storage, while also showing the customer that no one has opened the packaging before them. They are suitable for creams, butters, balms, scrubs, salt baths, or powder blends packed in jars and containers with a screw-on lid.

The adhesive layer of the liner is activated by pressure from the lid when it is tightened. No heat or induction machine is required, making it suitable for small production facilities and home manufacturing where containers are filled one by one. The liner is intended for contact with cosmetic products.

How a sealing liner works

The liner is placed inside the lid with the adhesive side facing the neck of the jar. When the lid is tightened, the adhesive layer is pressed against the rim of the neck and bonds to it. On first opening, the liner stays on the neck and the user peels it off. The lid is free and residue-free after opening.

The bond is mechanical, not welded as with induction sealing. It protects the contents from leaking when tilted and from drying out at the neck rim, but it is not a hermetic seal resistant to negative pressure or prolonged liquid pressure.

What you get

• Leak protection – cream or balm cannot get between the neck and the thread during transport, keeping the lid clean.
• Visible first opening – an intact liner gives the customer confidence that the contents have not been opened or tested.
• Reduced drying out – the layer on the neck limits air access to the surface of the product before first use.
• Easy application – simply insert into the lid and tighten, no equipment or heating required.

How to use the liners

Fill the jar to its nominal volume, not to the brim. The nominal volume is the declared fill; the total volume to the brim is larger, and the free space below the neck leaves room for the lid and liner. The neck must remain clean and dry so the adhesive layer has something to bond to. If the product gets onto the neck during filling, wipe it off before fitting the lid. Place the liner into the lid with the adhesive side facing the neck, screw on the lid, and tighten it firmly. The adhesive layer only bonds to the neck when fully tightened, so do not fit the lid loosely.

The liner size must match the inner diameter of the lid and the diameter of the jar neck. The exact size can be found in the product parameters; jars and lids with a matching neck are available from Handymade. If combining your own container and closure, we recommend checking that the liner sits securely in the lid and adheres around the entire neck circumference after tightening.

Good to know

Adhesion depends on the material of the neck and the condition of its rim. If the rim is rough or damaged, the liner may partially detach. The adhesive layer is sensitive to grease: if the neck is coated with oil or butter, the bond will be weaker.

The liner is intended for single use. Once peeled from the neck, do not reattach it — the adhesive layer no longer holds reliably. When refilling a jar, insert a new disc. The liner is made of polyethylene (PE) and should be sorted as plastic waste after use.

Frequently asked questions