CR4® - The Engineer's Place for News and Discussion®

Elasto Proxy's Sealing Solutions Blog

Elasto Proxy's Sealing Solutions Blog is the place for conversation and discussion about the design and custom fabrication of rubber and plastic components. For nearly 25 years, our family-owned company has provided high-quality, low-volume seals to a variety of industries. Doug Sharpe, Elasto Proxy's co-founder, is a former president of the International Sealing Distribution Association (ISD), a not-for-profit trade association that enhances member success through information, education, and interaction. By blogging for CR4 in this same supportive and collaborative spirit, Doug and other members of the Elasto Proxy team will share our experiences with you.

Neoprene Rubber for Sealing and Insulation

Posted February 12, 2018 10:55 AM by Doug Sharpe

When is neoprene rubber the right choice for sealing and insulation? This synthetic elastomer isn’t new, and chemists have created many other materials since neoprene was invented in 1930. Yet neoprene offers an excellent balance of properties, especially for industrial rubber products that require resistance to hydrocarbons, heat, flexing, and vibration.

In this article from Elasto Proxy, you’ll learn how neoprene offers advantages for a variety of applications. Engineers and buyers can specify various types of neoprene rubber, including grades that are approved or certified according to regulatory requirements or industry standards. You’ll also learn how neoprene rubber materials support custom fabrication for seals, gaskets, and insulation.

Neoprene Advantages

Neoprene or polychlorprene is a family of synthetic rubbers that’s produced by the polymerization of chloroprene, an organic compound. For sealing and insulation, neoprene offers these advantages:

  • Resistance to petroleum-based products such as oils and greases
  • Physical toughness, including resistance to damage from twisting or flexing
  • Resistance to ozone, water, weather, and a wide range of indoor and outdoor temperatures
  • Polymerization that supports custom compounds with specialized material properties

Neoprene also exhibits good chemical stability, especially with solvents. This oil-resistant rubber supports the use of adhesives and provides cushioning, abrasion resistance, and protection against vibration.

Neoprene Applications

Neoprene products are used in mobile equipment, defense, medical and healthcare, stainless steel and food equipment, infrastructure, and aerospace applications.

Heavy trucks, ambulances, military land systems, aircraft refueling systems, the mass transit industry, and makers of mining, construction, and forestry equipment use neoprene components such as:

  • Vibration mounts
  • Shock absorber seals
  • Hose covers
  • Power transmission belts
  • Tail light seals

Buildings, bridges, electrical systems, and industrial machinery applications use neoprene parts such as:

  • Seals for windows, HVAC units, and electrical or electronic enclosures
  • Expansion joints and bearing pads
  • Noise isolators in power transformers
  • Weather stripping for fire doors

The medical and healthcare industry uses neoprene rubber for orthopedic braces and supports. Because neoprene is latex-free, allergic reactions and skin irritation are minimized. Antimicrobial neoprene that prevents the growth of bacteria, fungi, and yeasts is available for medical and food processing applications. Neoprene rubber is also used for cushioning with medical instrument cases.

Neoprene Approvals and Materials

Commodity rubber is less expensive, but neoprene with specific approvals or certifications are required for some applications. Examples include:

  • UL 94 for flame resistant gaskets in electronic devices and electrical enclosures
  • ASTM E162 for surface flammability and ASTM C11166 for flame propagation in railcars
  • SMP 800C for toxic gas generation in the mass transit industry (subways, buses, and trains)
  • FDA approved neoprene for medical devices and equipment
  • MIL-G-1149 and MIL-R-15624 for military applications
  • AMS 3205 low-temperature and AMS 3208 weather-resistant neoprene for aerospace

Neoprene rubber is supplied as sheets, rolls, and profiles in various durometers and colors. Neoprene fabric is also available. Neoprene supports molding and extrusion, and comes in solid, sponge, and foam materials. Open cell neoprene contains interconnected pockets so that air, water, and other gases or fluids can pass through when the elastomer is not compressed. Closed cell neoprene is waterproof.

Custom-Fabricated Neoprene Products

Neoprene seals, gaskets, and insulation are custom-fabricated via water jet cutting, lamination, joining, and taping. Water jet cutting is ideal for prototyping and low-to-medium volume production because there’s no tooling or waiting for tooling. Lamination bonds neoprene sheets or fabrics into multi-layer, composite structures. Joining connects or splices the corners of cut lengths into finished gaskets. Taped neoprene gaskets support peel-and-stick installation for temporary or permanent fastening.

Find Neoprene Rubber Seals, Gaskets, and Insulation

Do you need neoprene rubber products for sealing and insulation? Elasto Proxy is an experienced custom-fabricator that provides design assistance, help with compound selection, and value-added services such as custom packaging, parts marking, and warehousing. To learn more, contact us.

Add a comment

Nitrile Rubber for Sealing and Insulation

Posted January 29, 2018 5:48 PM by Doug Sharpe

When is nitrile rubber the right choice for sealing and insulation? This common elastomer is known by many names, including Buna-N, NBR, and acrylonitrile butadiene. There are plenty of trade names for nitrile, too. No matter what you call it, nitrile rubber offers good resistance to oils, fuels, and chemicals. Temperature and environmental conditions are limiting factors, however, and may require the selection of a more expensive material such as Viton™.

In this article from Elasto Proxy, you’ll learn about nitrile’s advantages and disadvantages. You’ll also examine NBR compounds, compare commercial and specialty Buna-N, and consider some typical nitrile applications. Elasto Proxy supplies specialty nitrile products to a variety of industries and can create a custom sealing solution that meets your specific requirements. Nitrile isn’t the only oil-resistant elastomer, but it’s a cost-effective choice compared to some other compounds.

Nitrile Advantages and Disadvantages

Nitrile rubber provides good-to-excellent resistance to many oils and solvents. Examples include:

  • animal and vegetable oils
  • crude petroleum oil
  • kerosene and gasoline
  • liquified petroleum (LP) gases
  • motor oils
  • mineral oil based hydraulic fluids
  • silicone greases and oils

For engineers and buyers, it’s important to understand that nitrile’s resistance to petroleum oils is limited by temperature. According to most chemical resistance charts, nitrile resists petroleum oil at temperatures up to 250° F (121° C). If your application requires both oil resistance and higher temperature resistance, a fluorocarbon such as Viton™ may be required instead. Nitrile is also unsuitable for highly polar solvents such as acetone, which is used in some food processing and medical applications.

Nitrile’s advantages include good physical properties such as resistance to compression set, tearing, and abrasion. Typically, NBR or Buna-N comes in durometers (Shore A) ranging from 20 to 95 for applications that require a softer or harder rubber. Nitrile resists water, but provides poor resistance to weather, ozone, and aging. Acrylonitrile butadiene is also unsuitable for some applications because Buna-N won’t withstand temperatures that are colder than -40° F (-40° C).

Nitrile Compounds and Specialty Grades

Through compounding, material suppliers have developed different types of nitrile with enhanced material properties. For example, hydrogenated nitrile butadiene rubber (HNBR) can withstand slightly higher temperatures than NBR and provides improved resistance to polar fluids. Carboxylated nitrile butadiene rubber (XNBR) has a higher compression set than Buna-N and offers improved tear and abrasion resistance. Nitrile can also be blended with polymers such as polyvinyl chloride (PVC).

For engineers and buyers, choosing the right type of nitrile may involve comparing commercial rubber to specialty grades. Commercial grades generally cost less and are available in higher minimum order quantities (MOQs). Specialty grades generally cost more and have larger MOQs, but they’re custom compounds with improved properties. ASTM D2000 provides a standard way to describe elastomers and uses the designations BF, BG, BK, and CH with both standard and specialty nitrile.

Nitrile Products and Custom Fabrication

Nitrile rubber products are used in the aerospace, defense, infrastructure, medical and health, and mobile equipment industries. Specific uses include:

  • floor mats
  • grommets
  • hydraulic hoses
  • lip seals
  • O-rings
  • oil seals
  • vehicle transmission belts

Nitrile rubber is also used in appliance seals, medical gloves, and the bumpers for bowling alleys.

Buna-N or NBR is supplied as sheets, rolls, and profiles. Most nitrile rubber is black, but other colors are available. Nitrile seals and gaskets are usually made of solid sheets or extrusions, but closed cell Buna-N sponge rubber is used in applications that require a conformable gasket material. Water jet cutting supports fast, precise NBR gasket fabrication and eliminates the need to pay for or wait for tooling.

Find Nitrile Rubber for Sealing and Insulation

Do you need nitrile seals or gaskets? Do you have questions about Buna-N, or are you wondering whether HNBR or XNBR might be a better choice your application? Maybe you’re considering Viton™ or a specialty grade nitrile when a commercial NBR would meet your requirements. For design assistance, help with material selection, and expert gasket fabrication, contact Elasto Proxy.

Add a comment

Five Things You Need to Know About Rubber

Posted January 22, 2018 7:54 PM by Doug Sharpe

Some engineers and buyers already know which type of rubber they need for sealing and insulation. Others may ask if rubber comes in colors other than black (yes, it does), or specify an elastomer that costs too much or won’t meet their application requirements.

Material scientists can spend their entire careers learning about rubber. Engineers and buyers don’t have time for such as singular focus. That’s why Elasto Proxy, a custom-fabricator of industrial rubber products, brings you this list of five things you need to know about rubber:

  • Durometer and compression drive seal performance
  • Chemical resistance can be critical – and complicated
  • Environmental resistance supports longer service life
  • Rubber parts have different tolerances than metal parts
  • The best seal and gasket designs aren’t an afterthought

Let’s take a closer look at why these things matter to your sealing success.

Durometer and Compression

Rubber can be as soft as a pencil eraser or as hard as a hockey puck. Durometer, a measure of hardness, is expressed as a number on the Shore A scale. Lower numbers indicate softer materials. Higher numbers indicate harder materials. Solid rubber profiles usually range from 30 to 120 durometer (Shore A). Sponge rubber also comes in different durometers, but some sponge rubber is harder than solid rubber.

Rubber materials that are harder are more resistant to compression set, the permanent deformation of a material after prolonged compressive stresses at a given temperature and deflection. If a rubber reaches compression set, the seal loses its ability to return to its original thickness when the compressive stress is released. Leakage may occur, and seal failure can result.

Chemical Resistance

Chemical resistance can be critical – and complicated. That’s why it’s important to identify all the chemical agents to which your rubber product will be exposed. For example, if you’re in the mobile equipment industry, you may need engine bay insulation that can resist both fuel oil and cleaning chemicals. The rubber seals on fuel tanks may need to resist both diesel fuel and biodiesel blends.

For each chemical, you’ll need to consider variables such as concentration, duration of contact, operating temperature and pressure, and the thickness of the rubber material. A rubber product’s dimensions can affect volume swell, an increase in physical size that’s caused by the swelling action of a liquid. Depending on your application, a thicker or thinner rubber material may be required.

Environmental Resistance

Environmental resistance supports longer service life. During compound selection, you’ll need to analyze everything from exposure to water, ozone, and sunlight to service temperatures and heat cycling. Tearing, abrasion, and flexural fatigue can also cause seal failure. Outdoor gaskets can face tough conditions, but even indoor gaskets such as oven seals need strong environmental resistance.

High and low temperatures are especially problematic for some elastomers. Excessive exposure to heat can affect material properties. At cold temperatures, gaskets can become susceptible to leaks. Frozen gaskets are prone to cracking. Ozone cracking, a different condition, happens in sharp corners where strain is the greatest. If a gasket lacks UV resistance, sunlight can cause the rubber to become crumbly.

Part Tolerances

Part tolerances are allowable variations in the dimensions of manufactured components. If a part is out of tolerance, problems can occur. For example, if a door seal on a machine is out of tolerance, the door may be hard to shut or fail to provide proper sealing and insulation. Tight tolerances are possible with metal channels, but not with rubber extrusions that are sensitive to temperature and use different tooling.

Engineers understand part tolerances for metal components, but may be less familiar with tolerances for rubber parts such as door and window seals. Sometimes, an engineer specifies a tolerance that would be fine for a metal part, but not for a rubber profile. That’s why the Rubber Manufacturers Association (RMA) publishes tolerances and defines classes you may add to add to your part drawings.

The Sooner, The Better with Seal Designs

Finally, engineers and buyers need to know that “the sooner, the better” applies to seal design. If you wait to design your gasket until the rest of your product is complete, you may discover that there’s not enough room the for the seal. Then, even if you don’t have to redesign your product, you may need to use a more expensive gasket material and in higher minimum order quantities (MOQs).

Custom rubber takes time to develop and deliver, too. Sample development and lead times aren’t the only considerations. With rubber profiles, you’ll need to an extrusion die and a splicing die. If a sample doesn’t meet your needs, you may need to pay for and wait for new tooling. Then, once you receive another sample, you’ll need to determine if the seal fits your product and performs as required.

Ask Elasto Proxy

Do you need custom seals, gaskets, or insulation? Elasto Proxy keeps over 750 rubber profiles in stock and specializes in the custom fabrication of low-to-medium volume quantities. If you’re ready to get started, we can send you an Elasto Pak to support your seal designs. This sample kit lets you hold in your hand some of the rubber products we can custom-fabricate for you. To learn more, contact Elasto Proxy.

Add a comment

Commercial Grade Rubber vs. Specialty Rubber: Make the Right Choice

Posted January 15, 2018 2:16 PM by Doug Sharpe

Commercial grade rubber provides sealing and insulation for a wide variety of applications. Compounds such as commercial grade EPDM, silicone, and neoprene also cost less than specialty rubber materials that meet standards, approvals, or regulatory requirements from organizations such as ASTM International, Underwriters Laboratories (UL), and the U.S. Food and Drug Administration (FDA).

For engineers, choosing the right rubber means understanding when a specialty material is required, and when a commercial grade rubber is sufficient. Engineers want to make sure that the products they design meet application requirements, but over-specifying an elastomer can incur unnecessary costs. In addition to paying more per unit of material, you may have to buy greater minimum order quantities (MOQs).

In this article from Elasto Proxy, we’ll consider the differences between commercial grade rubber and specialty rubber in terms of some real-world examples. You’ll also learn about some best practices that can strengthen your seal designs.

Asking for ASTM Rubber

Sometimes, engineers ask for “ASTM rubber” or an elastomer that “meets ASTM D 2000”. There are several challenges here. First, there isn’t a single ASTM test standard for rubber materials. In fact, there are many different and specific testing standards. Do you need an elastomer that meets the thermal conductivity requirements of ASTM F433-02(2014)e1? Maybe you need a gasket material that meets the minimum liquid leakage requirements of ASTM F 37-06(2013) instead. If you don’t need a specialty rubber that meets an ASTM test standard, could you use a commercial grade compound that costs less?

ASTM D 2000 is a published specification that provides buyers and suppliers with a standard way to describe vulcanized elastomers. Asking for “ASTM D 2000 rubber” instead of “ASTM rubber” may seem more specific, but it’s not. ASTM D 2000 covers thousands of elastomers and uses a combination of letters and numbers to “call out” material properties. To use a food-related analogy, simply asking for “ASTM D 2000” rubber is like ordering a sandwich without specifying the bread, fillers, or condiments. Unless you’re incredibly lucky, the sandwich you receive probably won’t be the one you thought you’d ordered.

Asking for UL 50 Gaskets

UL 50 applies to enclosures for electrical equipment that will be installed and used in non-hazardous locations in accordance with national electrical codes in Canada, the United States, and Mexico. This standard applied to the entire enclosure, however, and not to individual components such as seals, gaskets, and insulation. In fact, UL 50 states that if an individual product has requirements that are at variance with UL 50, then the requirements for the individual product takes precedence.

Sometimes, however, engineers ask for “UL 50 gaskets” when a UL 50 approved material is not required. There are several challenges here. First, a well-designed enclosure may be able to meet UL 50’s requirements without the use of more expensive UL-approved gasket materials. Second, there is a separate UL standard (UL 50E) for the environmental construction of qualifying environmental enclosures. During the design process then, engineers may need to account for two separate but related standards. If the electrical enclosure is for an appliance, then UL 94 may apply to your gasket design instead.

Commercial Grade Rubber, Specialty Rubber, and Best Practices

Asking for a “rubber gasket” but including “UL 50 gasket” or “ASTM rubber” on your schematic is also problematic. Ultimately, your part drawing is your contract for gasket fabrication. That’s why Elasto Proxy helps you not just with material selection, but with seal design. If you use a CAD application such as SolidWorks®, we can send you DWG files of standard profiles that you can drop into your design. We can send you PDF versions of our standard profiles, too.

Are you wondering whether you need commercial grade rubber or specialty rubber? Do you have questions about seal design? Don’t wait until the end of your next project to ask for assistance. Otherwise, you may need to use specialty rubber because a commercial grade compound can’t support a design constraint. To learn more, contact Elasto Proxy.

Add a comment

Four Values That Define Elasto Proxy

Posted January 11, 2018 10:49 AM by Doug Sharpe

Core values describe what we believe and guide the way that we act. These deeply-held values also serve as a mirror of sorts. When a company’s behavior reflects its core values, employees see this consistency. Customers and vendors recognize integrity, too. Inside and out, a company needs to be true in both word and deed. That’s why at Elasto Proxy, we don’t just talk about our core values. We show you who we are in all that we do.

Maybe you’ve done business with Elasto Proxy for years. Maybe you’re a new customer or vendor. Regardless, we’d like you to know more about who we are and what our core values mean for you. Elasto Proxy is a growing, global company that’s powered by problem solvers. We’re also engaged, professional, and loyal. Regular readers of our blog have come to appreciate our application knowledge and technical expertise. But do you know how our core values support your success?

Problem Solvers

Elasto Proxy is a team of creative and proven problem-solvers. For over 25 years, we’ve been solving design and manufacturing challenges with low-to-medium volumes of seals, gaskets, and insulation. You may know us as a rubber fabricator, but Elasto Proxy also adds value through design assistance and help with material selection. For example, when you send us your part drawings, we can suggest design improvements. We can also help you to avoid paying too much for a material that you don’t really need.

At Elasto Proxy, we combine state-of-the-art equipment with traditional pride-in-craftsmanship. Water jet cutting speeds processing times and ensures consistency. Our production team bonds gaskets and laminates materials with speed and precision, too. Other companies put price above all else, but Elasto Proxy doesn’t treat people and products like commodities. We can help you solve business challenges, too. From inventory management to logistics, we offer complete solutions.


Elasto Proxy is a company where people are engaged. They enjoy what they do and are passionate about honoring their commitments. Our employees also want to learn, grow, and accept new responsibilities. Continuous improvement and customer satisfaction aren’t just concepts here. They guide the way we do our jobs every day. That’s why Elasto Proxy hires hard-working people who will go the extra mile and are never satisfied. We also partner with suppliers who share our values and deliver on their promises.


Elasto Proxy is a professional organization. We encourage our employees to invest in themselves through training and education. We also provide hands-on, in-house instruction so that everyone understands what’s involved in custom fabrication. When you meet members of our sales team, you’ll notice their professional appearance. Yet our solutions providers have also worked side-by-side with our production team to understand the professionalism and dedication that’s required for top-notch manufacturing.


Last but certainly not least, Elasto Proxy is loyal. At all our branches, we treat each other with respect and maintain a family-like atmosphere. We’re health-conscious, too. From holiday celebrations to road races, we enjoy each other’s company. We also value long-term relationships with our customers and vendors. By partnering with organizations that share our values and goals, we can achieve win/win solutions. It takes time to understand each other, but it’s time well-spent.

What Are Your Core Values?

What are the core values that describe what your company believes? Which deeply-held values guide the way that you act? Are you looking for a partner instead of just a parts provider? Elasto Proxy is a more than a custom-fabricator of seals, gaskets, and insulation. We’re a creative problem solver that’s engaged, professional, and loyal. To learn more about us, contact Elasto Proxy.

Add a comment

Previous in Blog: Five Things to Know About Elasto Proxy's Capabilities  
Show all Blog Entries in this Blog