Trim Seals

Trim seals (also known as bulb seals) are often used for weather stripping in automotive, marine and transportation applications. These seals couple reliable sealing performance with a finished appearance. Widely utilized in vehicle sealing, trim seals are employed around door frames, hood, trunk and hatch openings, and other body appurtenances.

What are trim seals?

Trim seals are often referred to as bulb seals because of their design. The seal usually consists of a retainer section fabricated from a harder rubber which is mated to a flexible bulb made of softer rubber. Alternatively, the seal may be made from a single rubber of uniform hardness. Sometimes, a reinforced carrier consisting of a flexible wire or segmented steel core is incorporated into the seal design to provide additional reinforcement and strength. Trim seals are usually produced by molding or extrusion.

What materials are used to make trim seals?

Because they are often used to seal body openings, bulb seals are made from rubber compounds that offer excellent resistance to water, sunlight, and ozone. Materials used to manufacture trim seals include elastomers and sponges. EPDM, neoprene, thermoplastic elastomers (TPE), and silicone compounds are often used. These compounds are good material solutions for providing a weatherproof seal that is impervious to the elements and degradation from ozone and UV light.

EPDM is a synthetic rubber that withstands temperature extremes and exhibits excellent resistance to UV light. Fire-resistant grades of EPDM are also available. TPE materials combine the best properties of rubber and thermoplastics. While parts made from TPE do not recover as well from heat and compression, they do offer excellent flexibility and resistance to weathering and ozone. Silicone rubber is a preferred material choice for automotive edge trim seals where low toxicity and reactivity to chemicals are required.

What applications do trim seals support?

As noted above, trim seals are widely used to seal body openings in automotive, mass transit, commercial and military vehicles. Other applications include the sealing of recreational vehicles (RV), boat hatches, storage compartments, tool boxes – in fact, around any edge where a solid, reliable, and finished seal is required.

Trim seals from CRG

CRG has provided custom molded and extruded trim seals to the vehicle programs of leading OEM’s. In servicing these projects, we have drawn upon our capability to supply seals with single and double bulbs, as well as those with butyl or slip coating added to the trim. If required we can supply trim seals fabricated using multiple materials and densities.

CRG has over 30 years’ experience in supplying automotive OEM’s and Tier 1-3 suppliers with sealing solutions and products. In every project, we are focused on adding value for our automotive customers, including part testing, proving and prototyping, supplying kanban quantities, and inventory warehouse management to support JIT delivery.  Our experienced team is always available to offer material selection guidance, Production Part Approval Process (PPAP), CAD drawing support, EDI, bar coding, and global logistics management.

Many of the world’s leading automakers, including General Motors, Ford, Chrysler, Toyota, and Mercedes-Benz, rely upon CRG to supply their automotive rubber needs.

To find out more about the trim seals which CRG can supply, please contact our sales department at