Custom Gasket Strips

Custom gasket strips are specialized elastomeric strips, typically with an adhesive backing, that are used in applications where a standard gasket tape isn’t sufficient. They provide environmental sealing against water and dust and thermal protection. Gasket strips can be cut to size as needed.

Custom Gasket Strips: The Stockwell Advantage

Stockwell Elastomerics maintains a full inventory of high performance materials for custom gasket strips, or strip gaskets as they are also called. These materials include:

• Solid silicone in low durometers (soft)
• Silicone sponge from Saint-Gobain
• Silicone foam from Saint-Gobain or Rogers Corporation
• PORON® urethane foam from Rogers Corporation

Strip gasket materials can be laminated with pressure sensitive adhesives (PSAs) and cut into custom products, typically without any tooling charge. The key benefit to using a strip gasket is the efficient material utilization for large enclosures.

Stockwell Elastomerics is a Rogers Corporation Preferred Converter; Rogers makes PORON microcellular urethane foam. Stockwell Elastomerics is also a 3M Preferred Converter, which provides PSAs. All manufacturing of custom gasket strips happens in Philadelphia, Pennsylvania (USA).

What are Custom Gasket Strips?

Custom gasket strips are long, thin gaskets that seal gaps between two mating surfaces. They are supplied as tapes or rolls and can be cut to size. Typically, custom strip gaskets are used for water sealing and/or dust sealing in electronic enclosures and electrical housings. They are also used for thermal protection. Often, custom gasket strips are more flexible than traditional rubber gaskets.

Strip Gasket Performance vs. Single Piece Gaskets

The performance properties of strip gaskets makes them a good choice for specific sealing applications. Sometimes, however, single piece gaskets are recommended instead. Examples include:

• Submerged Water Sealing – Submerged gasket applications generally require single piece gaskets rather than strip gaskets. Solid gasket materials such as low durometer (soft) silicone perform well in these environments.
• Hose Down Water Sealing – Single piece gaskets work best for hose down water sealing. However, interlocked or bonded gasket strips may be sufficient depending on the enclosure design and water pressure. Closed cell sponge, closed cell foam, and solid gasket materials (soft silicone) all perform well.
• Dust and Light Splashing – Gasket strips usually work well. Open cell foam, closed cell sponge, and closed cell foam are commonly specified.
• Compression Set Resistance – PORON® cellular urethane, silicone foam and closed cell silicone sponge have better compression set resistance than low cost blended neoprene and PVC foams. For indoor applications such as industrial controls, PORON is a good value for long term performance. For outdoor enclosures that are subjected to a range of environments, silicone foam or closed cell silicone sponge perform better over time.

Strip Gasket Manufacturing vs. Gasket Tape Manufacturing

Strip gaskets and gasket tape have some important differences in terms of manufacturing.

• Strip gaskets can be made from any variety of roll stock material such as silicone foam, urethane foam, silicone sponge, or neoprene sponge. These materials are typically provided with an adhesive, peel-and-stick backing for ease of installation.
• Gasket tape is made by slitting a master roll of material to a prescribed width. The length may be specified, but there are limitations based on the thickness of the material and master roll put-up.

Adhesive Backings for Custom Gasket Strips

Stockwell Elastomerics offers over 20 pressure sensitive adhesives. Most adhesives that are supplied on materials fall into 3 categories.

• Film Supported Acrylic (also known as double coated PSA) – PSAs are constructed by coating each side of a thin PET film with adhesive. When a supported PSA is laminated to a “stretchy” rubber material, the thin PET film gives the strip gasket (or gasket tape) dimensional stability. This is useful to prevent an assembly technician from stretching the strip gasket during installation. The recommended adhesive for general purpose applications is Adchem 256M acrylic adhesive.
• Unsupported Transfer Film – These are .002″ to .010″ films of adhesive on self-wound rolls of release liner. To reduce the number of butted splices, transfer film adhesives can be stretched and conform to uneven surfaces or bends during installation. The recommended transfer adhesive backing for strip gaskets is 3M 9485 acrylic (0.005″ thick). Unsupported transfer film adhesive is suitable for cast metal enclosures and sheet metal enclosures with uneven surfaces. The recommendation for this application is 3M 350 series (9485, 9675) acrylic transfer film adhesive.
• Low Surface Energy Adhesives – LSE adhesives have been developed to adhere to “tough to stick to” materials such as powder-coated metal surfaces and some plastics. LSE adhesives are available in film supported constructions such as 3M 9490LE and transfer film adhesives such as 3M 9675, 3M 9485 and 3M 9472LE.

Applications for Custom Gasket Strips

The most common applications for custom gasket strips are dust and water protection for large enclosures, oven doors, and as electrical housing gaskets. With sealed enclosures, custom gasket strips can be used for the following IP ratings: IP61, IP62, and IP63. Aggressive wash down requirements such as IP64, IP65 and IP66 may require bonded corners to prevent the ingress of pressurized water. The same holds true for NEMA 4 and UL 50 enclosure gaskets.

How to Buy Adhesive Backed Gasket Strips

Stockwell Elastomerics manufactures custom gasket strips based on a customer’s specific needs. To buy an adhesive backed gasket strip, the required information is:

• Strip width
• Material thickness
• Type of pressure sensitive adhesive (PSA) backing

Stockwell Elastomerics can help customers with material selection, adhesive selection, and recommended or ideal widths and thicknesses.

Note: With the slitting process, there typically is a minimum order requirement.

PORON® is a registered trademark of Rogers Corporation.