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The Elastomerics Blog by Stockwell Elastomerics

Tuesday, July 01, 2014

Silicone Foam Port Plugs for Environmental Test Chambers

environmental chamber plugs
layered foam plug
silicone foam port plug, layered
silicone foam plugs for environmental chambers
silicone foam port plugs

Stockwell Elastomerics manufactures replacement foam port plugs for environmental test chambers. Silicone foam plugs have excellent temperature and humidity resistance and offer very good thermal insulation. Custom sizes and profiles are available without any tooling charge; most plugs are slightly oversized to make a tight fit/seal in the port.

Stockwell Elastomerics’ silicone foam port plugs are made in several configurations.  The white, single piece plugs are available with or without a dense closed cell top layer (grey layer shown in picture).  A lower cost and short lead time option is the layered silicone foam plug (shown in black).  The layered foam port plugs are made from bulk produced silicone foam that has skin on each side and fine pitch cells.  The layered version does not require the additional grey top layer but is still available.

For more information or to order silicone foam port plugs for environmental test chambers, please contact Stockwell Elastomerics at 1-800-523-0123 or email

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posted by Steve Hughes at 4:43 PM

Monday, June 02, 2014

EMI Gasket Material with Conductive Reinforcement

EMI management is a must for OEMs manufacturing electronic devices or equipment containing electronics.  EMI gaskets made from rubber material such as silicone and fluorosilicone lose some physical strength due to the conductive particle fill.  This is most apparent in tensile strength in thin EMI gasket materials. To address this, Stockwell Elastomerics now offers components manufactured from SNE-556-R conductive silicone EMI gasket material with a conductive reinforcement.

SNE-556-R is 65 durometer (Shore "A") with volume resistivity that challenges high cost silver coated aluminum filled products, but at a fraction of the cost. Additionally, it is manufactured in continuous sheet rolls allowing for manufacturing large EMI gaskets. The reinforcement enhances the conductivity of the rubber as well as giving dimensional stability to cut parts. An example is an EMI enclosure with many bolts, the reinforcement prevents the gasket from stretching during installation ensuring holes in the EMI gasket align well with the fastener hole in the enclosure.

Benefits of SNE-556-R reinforced EMI gasket material:
  • High Conductivity EMI gasket
  • Continuous EMI Sheet Roll
  • Cost benefit from nickel graphite filled silicone
  • Dimensional stability of cut EMI shielding gaskets
  • Environmental sealing EMI Gasket
  • Available with 3M conductive adhesive backing
Stockwell Elastomerics manufactures EMI gaskets and EMI shielding components for the technology and defense sectors.  Products include, molded EMI components for medical device, waterjet EMI gaskets for defense and aerospace, EMI connector gaskets and emi card cage gaskets for a multitude of industries.

For more information on SNE-556-R reinforced EMI gasket material and other silicone gaskets, please contact Stockwell Elastomerics at 1-800-523-0123 or email,

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posted by Steve Hughes at 1:59 PM

Wednesday, May 07, 2014

Digital Signage Gasket, Protecting Capital Investment

Electric signage is going through its digital revolution; as cost of hardware decreases and connectivity improves, digital signage is becoming the preferred means of advertising. Examples include: large outdoor LED billboards, electronic posters, interactive kiosks and touch screens. As with most electronics, digital displays need to be protected from their environment. Outdoor signage needs to function in a wide range of conditions such as wind driven rain, snow, and extreme temperatures.  Interactive advertising needs to be protected from rough use and spills. An additional consideration is the management of electromagnetic interference (EMI).

While relatively new to signage and advertising, these environmental and EMI consideration have been managed for many years in industries such as telecommunications, outdoor lighting, electric controls and military electronics. Stockwell Elastomerics has been providing sealing solutions and ruggedizing materials to OEMs for decades.  With a wide range of materials and manufacturing capabilities, Stockwell offers high performance gasket tapes as well as custom cut parts. Applications engineers are available to help specify the most cost effective material and process to meet performance and regulatory requirements.

In the works is UL 48B, which will address digital signage.  UL 48B will have the same basic requirements for gaskets as UL 48 (electric signage); however display manufacturers will likely need to surpass these due to the more sensitive electronics. Additionally, many indoor or public use displays may require materials that meet UL94 flame requirements.

Material Touch Brochure Available for UL 48 SAM

Stockwell Elastomerics offers Applications Engineering support to help with material selection. Having comprehensive inventory and in-house manufacturing allows Stockwell to manufacture pre-production through full production quickly.
For more information on gasket solutions for digital signage and interactive digital displays, please visit, email or call 1-800-523-0123.

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posted by Steve Hughes at 11:55 AM

Tuesday, April 15, 2014

Open Cell Foam vs. Closed Cell Foam

Stockwell Elastomerics inventories hundreds of gasket materials and cushion materials to meet a wide range of performance requirements. While applications such as mobile military electronics, outdoor lighting, NEMA enclosures all seem very different, they often share the need to withstand environmental conditions of heat, cold, UV, ozone and most importantly seal out water and dust.

To achieve a good water seal there are several factors, the most important is selecting the proper material.  Sealing sheet metal or plastic enclosures very often need soft, expanded rubber materials that can be readily compressed. Many of the rubber gasket materials like silicone, urethane, neoprene, EPDM are available in expanded form; an analogy is like adding yeast in bread, a blowing agent is mixed with these polymers to make them expand creating pockets of air.  Most water sealing applications requires these pockets to be closed off from each other, called closed cell foam or closed cell sponge.  When the pocket are open to one another, they are called open cell foam or open cell sponge.

Open Cell Example: A kitchen sponge has open cells; the open, connected cells allow water to pass from one cell to the other, allowing it to hold water used for cleaning.
Closed Cell Example: A scuba diver's wetsuit, where the adjacent cells are closed off from one another.  The trapped air in the neoprene make it soft and lightweight yet does not absorb water even under pressure of being submerged.
The video below shows two expanded silicone products, an open cell silicone foam and a closed cell silicone sponge.  Aside from the water picked up from the cut cells on the edges, the close cell gasket material does not absorb water.

For more information on closed cell rubber for water gaskets and open cell foams for dust and light spray gaskets.  Please visit, email or call 1-800-523-0123.

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posted by Steve Hughes at 10:42 AM

Sunday, March 02, 2014

New! 480S Gasket Tape from Stockwell Elastomerics

Silicone Gasket TapeStockwell Elastomerics is committed to manufacturing and delivering products that solve engineering challenges.  480S Gasket Tape is Stockwell's newest offering, combining the softest, UL 50E, closed cell silicone sponge with a strong 3M acrylic adhesive.

Stockwell's 480S soft gasket tape is an excellent option for enclosures or signs where door or plastic can flex such as electrical enclosures with spaced out door latches.  The low compressive force needed to seal help limit bowing which is a common point of water ingress.  This also applies to UL 48 signage gaskets where plastics are susceptible to flexing.
Benefits of 480S Gasket Tape
• Soft, requires low clamp force
• Closed cell - no wicking through material
• Low compression set - rebounds very well
• UL 50E silicone sponge
• UL 746C adhesive
• UV and ozone resistant
• Long life

Common Applications
• NEMA gasket
• IP64 and IP65 gasket
• LED lighting gasket
• Kiosk and large touch panel seals
• Digital Display Gasket
• Electric sign gaskets
• Gaskets needing to meet Mil-810 requirements

To request a new Gasket Tape touch brochure please click here.  For more information about other Gasket Tape products offered by Stockwell Elastomerics or custom manufactured gaskets, please call 1-800-523-0123 or email

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posted by Steve Hughes at 11:45 AM

Thursday, February 27, 2014

Automated Dovetail Gaskets and Other Bonded Gaskets

Engineers tasked with designing enclosures to protect sensitive electronics are often pressed to specify maintenance free gaskets while keeping cost down. There are many materials to choose from but when long term performance is needed, silicone materials are a top choice.

Benefits of Silicone Gasket Materials
  • Very low compression set
  • UV and ozone resistant
  • UL 50E gasket materials readily available
  • Suitable for NEMA gaskets and IP 6X gaskets
  • UL 94V-0 gasket materials available
  • Long performance life
The lure of using a low cost material may result in short term sealing effectiveness that is at risk of failure in the field due to compression set and stress relaxation. Generally, the cost of a field repair far exceeds the cost of better gasket material. At Stockwell Elastomerics, we focus on offering long lasting gaskets manufactured from high quality materials, helping to protect expensive equipment from outdoor elements for its anticipated life.

Automation to Reduce Gasket Cost
Stockwell Elastomerics invested in a custom, automated ultraviolet bonding system to increase throughput and reduce manufacturing cost of bonded gaskets. Cutting individual legs of the gasket and bonding them offers significant cost savings for large gaskets such as NEMA enclosure gaskets, electric signage gaskets (UL 48 gasket) and digital sign gaskets.

Effects of Gasket Joints on Compression
Using proven designs and analytical instruments, we can quantify and test the effects of our dovetail bonding techniques for your application. In the graph below you will see an example of how the force of deflection at a location on a gasket changes with different constructions. This information can be used to help guide a gasket design and ensure proper forces are experienced between mating features.

For more information about UV bonded gaskets, jointed gaskets, and gasket tape for large gasket applications or electrical enclosures, please call 1-800-523-0123 or email We will apply our experience with materials, process, and fabricating to make an offering that solves your problems.

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posted by Alex Santayana at 9:42 AM

Thursday, January 30, 2014

Silicone Gasket Manufacturer

Stockwell Elastomerics is a leading gasket manufacturer with a core competence in high performance silicone materials.  Stockwell manufactures custom gaskets and pads from a wide range of materials including neoprene, urethane, EPDM, and other organic rubber materials; however for many critical, long life, environmental gaskets, silicone materials have the best properties.

Applications needing to meet IP64, IP65, IP66, IP67, NEMA 4X, or UL 50E often require long term performance.  Common application such as Telecom enclosures, LED lighting, digital signs, and smart grid nodes are intended to perform in the field for many years.  This means the gasket material that seal out rain, snow, and dust needs to last a long time without degrading. The life or performance of many organic black rubber materials area adversely affect by UV, ozone, time and temperature cycling, where silicone performs very well.

Stockwell Elastomerics manufactures silicone gaskets and components in variety of ways to meet the needs of a typical product design cycle.  Pre-production parts are often waterjet cut.  Production parts can be die cut from silicone sheets or liquid silicone injection molded.

Silicone Rubber Materials:

Solid Silicone Sheets or Injection Molded Silicone
- Soft silicone rubber (10 – 20 durometer)
- Medium silicone rubber (30-50 durometer)
- Firm silicone rubber (60 – 70 durometer)

Expanded Silicone Sheet
- Open Cell Silicone Foam
- Closed Cell Silicone Foam
- Closed Cell Silicone Sponge

EMI Silicone Gasket
- Nickel Graphite Silicone (particle filled)
- Silver coated aluminum (particle filled)
- Monel mesh & closed cell sponge (bonded)

Thermally Conductive Silicone
- Gap filler
- Conductive silicone sponge
- Conductive solid silicone
- Conductive silicone coated fabrics

For more information on how Stockwell Elastomerics can manufacture your custom gasket, please call 1-800-523-0123 or email

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posted by Steve Hughes at 1:48 PM