Silicone O-Rings and PTFE Liners

Inside almost every closure is a small component that does the actual sealing. Silicone O-rings and PTFE-faced liners are the parts to specify when an ordinary foam or PE liner is not enough. A PTFE facing is about as chemically inert as a sealing surface gets: it stands up to solvents, acids, oils and high-alcohol products that attack standard liners.

Silicone O-rings add a compressible, resilient seal that holds across a wide temperature range, which is why they are used in food, pharmaceutical and laboratory assemblies.

We supply these seals as cap and closure liners, as swing-top and ground-joint seals, and as O-rings for lab and process equipment. Typical products include solvents and acids, spirits and essential oils, pharmaceutical fills, and foods where a clean, inert contact surface matters. Many customers order them alongside our caps and bottles as an upgrade — swapping a standard foam liner for a PTFE-faced one, for example, when moving a cap to a more aggressive formula.

O-rings are molded from platinum-cured silicone in a wide range of internal diameters and cross-sections. Liners are laminated from a thin PTFE film bonded to a foam or board backing and die-cut to the cap diameter; the PTFE faces the product while the backing supplies compression. Food-contact and pharma grades are available, and we can supply material declarations for the grade you select.

Choose the seal for the product and process: PTFE-faced liners for aggressive solvents, acids, spirits and oils; silicone O-rings where a resilient seal through hot and cold conditions is needed. Match size and compression to the closure or joint, since over-compressed O-rings take a set and under-compressed liners leak. Send us the cap size or joint dimensions and your product, and we’ll recommend a material and supply samples for testing.

Silicone O-rings are compression- or injection-molded and deflashed; PTFE-faced liners are laminated and die-cut from sheet or roll stock. Dimensional accuracy, material grade and cleanliness are our key quality checks. We stock common sizes, cut liners to custom diameters, can insert liners into our caps before shipment, and pack seals bulk-bagged by size, with clean packing available for sensitive applications.