Seal Slip Coat, Flocking, Tape, Attachments, & Adhesion Promoters

A collage of multi-durometer thermoplastic extruded seals.

Seal Slip Coat, Flocking, Tape, Attachments, & Adhesion Promoters: Which Should You Choose?

Profile Extrusion, Seals

When thinking through a seal application design, don’t forget about slipcoat, flock, tape, attachments, and adhesion promoters.

Slip Coat

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A slip coat is a coating applied to the surface of a seal in order to reduce abrasion and increase seal life. Usually slip coating is applied to glass run channel and other dynamic seal applications. The job of the slip coat is to keep the seal working – allowing, for example, a glass window to move in and out – while not scuffing or marring the material running in and out of its channels. Slip coats keep seals from being harmed by cleaning products, they don’t fade over time, and generally are weatherproof.


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Flocking is similar to slip coating but has a definite look and texture – similar to velour. The process involves applying a flocking spray or flocking powder to the surface of the seal to insulate, absorb water, dampen vibration, and reduce friction. Most flocking is black because the seal it is attached to is also black. But, depending on the application, it can be dyed to match most other colors. Flocking is found in auto and home windows – and in many other applications demanding weatherproofing of some sort.


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Tape is a means of attaching a seal to another surface. Usually the seal is manufactured with an adhesive side affixed in place on the seal and a second adhesive side protected by a covering which is removed during a later stage of the manufacturing or assembly process.


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A seal attachment includes adhesives and mechanical fasteners. Both are meant to join a seal to another surface and each as its pro’s and con’s. Adhesive attachments (including tape) can be temporary or permanent and may work in conjunction with mechanical fasteners. Mechanical fasteners include wire carrier seals, kerf insertions, multi-durometer extrusions, and push-pin seals, one of the most common in the auto industry.

Adhesion Promoters

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An adhesive or adhesion promoter applied to a seal does exactly that — promotes adhesion of a tape or other material to a seal. Adhesion promoters improve bonding between substances that would normally resist bonding together, provides a quick-stick solution for two materials, and promotes bonding in curved or irregular surfaces.

Resources for Engineers

As you can see, seal applications can be complex manufacturing endeavors. If you’d like an expert opinion, Gemini Group has decades of experience with all of these and can recommend the right design for your application.


To learn more about seal material selection, please enjoy our free Engineers’ Guide to Selecting an Extruded Seal Material. Just fill out the form below to download.

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Contact Gemini

Gemini Group’s seal team is comprised of Gemini Plastics, Sierra Plastics, and GPM. To contact us, please call our sales engineering team at 248-435-7271 or email us at

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