Category Archive: Products

Material Spotlight: Mylar®

Electrical insulation is crucial in various applications to prevent the free flow of electricity. Mylar helps channel electricity where it needs to go while preventing short circuits and eliminating electrocution dangers. ESPE Manufacturing Co., Inc. has an enormous selection of materials to fabricate components and parts that can be used as electrical insulation, including Mylar.

What is Mylar?

In the 1950s, a trio of chemical companies, Hoechst, DuPont, and Imperial Chemical, developed Mylar–a stretched polyester film that is commonly used for solar filters, protective plastic coatings, insulators, space blankets, and shiny helium balloons. The technical composition of the groundbreaking material is biaxially oriented polyethylene terephthalate, or BoPET. NASA was one of the first to use and experience the benefits in its 1964 Echo II balloon.

To create Mylar, molten PET is extruded as a thin film over a chilled roller or other surface. Special machinery draws the film in biaxial directions using heated rollers. The final step involves setting the film by holding it under pressure at a high temperature. The result is an extremely smooth and pure film that adheres to itself. To prevent this, inorganic particles or metals can be embedded in the surface.

The properties of Mylar make it an excellent component for food packaging applications such as yogurt lids, roasting bags, and various foil packages. Because of its electrical insulating properties, it is often used in manufacturing, automotive, electronics, and space travel applications.


The properties listed below allow for an ideal choice in a wide variety of applications:

  • Dielectric strength. Mylar is an excellent electrical insulator with a typical DC dielectric strength of 11.0 kV/mil and a typical AC dielectric strength of 7.0 kV/mil.
  • Corona threshold voltage. Mylar has one of the highest corona resistance levels of any plastic film, which makes it able to endure short surges of overvoltages easily.
  • Dielectric constant. The typical dielectric constant ranges from 2.8 to 3.7, depending on the temperature of the film.
  • Dissipation factor. The typical dissipation factor of Mylar ranges from 0.0002 to 0.016, depending on the temperature of the film.
  • Insulation Resistance. Mylar film has exceptional insulation resistance over a broad range of temperatures.
  • Volume Resistivity. The volume resistivity of the material decreases as temperature increases, with Mylar Type C having about one order of magnitude higher volume resistivity than Type EL film at 257° F.
  • Tracking Resistance. When dry, the material doesn’t track, but moisture can lead to tracking erosion.
  • Arc Resistance. Mylar possesses an arc resistance time of 73 to 94 seconds. This shows that the material has an advantage over materials that track.

The Advantages of Mylar for Electrical Insulation

The benefits of Mylar film come from its excellent electrical insulation properties under a wide variety of conditions. In addition to those listed above, it also includes the following advantages for electrical insulation:

Tensile strength and toughness

Mylar is tough and has a higher tensile strength than most insulating materials. It has a tensile strength of 25,000 psi and elongation at 170% without breaking.


Creep measurements indicate how a material deforms under a wide range of mechanical stressors. Under various conditions, the material resists creep very well.

Thermal aging

UL thermal aging standards show that Mylar has a temperature index of 302° F. This means that it will not degrade at service temperatures below 302° F, providing a long service life for various electrical insulator applications.

Mylar Available from ESPE Manufacturing

Mylar is one of many electrical insulation materials, and it provides a particularly wide range of benefits for industries such as automotive, electrical, lighting, wind energy, and many others. At ESPE, we offer a wide range of electrical insulation materials to fit the specifications of your project. For more information about this material, or to get started on your electrical insulation solution, contact us or request a quote today.


What to Know About Electrical Insulating Materials


At ESPE Manufacturing, we specialize in the manufacture of high-quality custom plastic parts and products, including electrical insulating materials. We maintain an extensive inventory of non-metallic materials for use in our manufacturing operations and distribution to our customers. One of our core material offerings is electrical insulation. Below, we provide an overview of this material, including what it is, why it is needed, how it is used, typical applications, and types available.

The 5 Basic Aspects of Electrical Insulation

1. What Is Electrical Insulation?

Electrical insulation refers to materials that do not allow electricity to flow through them freely (e.g., rubber or plastic). In contrast, conductors and semiconductors do allow electricity to flow through them freely (e.g., copper). This difference in performance stems from the difference in their resistivity. Electrical insulating materials have higher resistivity than semiconducting and conducting materials, which means electrons do not pass as easily through the former as they do through the latter.

electrical insulating vs conducting materials

2. Why Is It Needed?

Electrical insulators help control the flow of electricity. They ensure energy reaches the desired destination within the system by acting as a barrier around the conductor, preventing the energy from straying from the preferred path. In doing so, they also prevent electricity from flowing to other components, which can cause short-circuiting or electrocution depending on the configuration of the system.

3. A Glimpse at the Process

The following illustration points out the process of electrical insulation:

electrical insulation

4. Applications That Use Electrical Insulation

Some of the primary applications that require electrical insulation include:

  • Automotive components
  • Computers and computer peripherals
  • Consumer products
  • Conventional and uninterruptible power supplies
  • Electrical and power distribution systems
  • Lighting
  • Medical equipment
  • Telecommunications equipment

5. Commonly Used Electrical Insulation Materials

There are many types of electrical insulation materials available. Some of the most commonly used include:

  • Cardboard/Paper: These materials are a cost-effective option for insulation applications involving low heat and voltages.
  • Clay (ceramic or porcelain): This material is the standard for high-voltage and radio-frequency (RF) insulators.
  • Glass (limestone, silica, and soda ash): This material is used occasionally in low-voltage applications.
  • Mica: This material offers good electrical insulation and thermal conduction properties.
  • Perfluoroalkoxy (PFA): This material is flexible, transparent, and chemical resistant. It is commonly used in near-ocean applications due to its salt spray resistance.
  • Rubber: This material was used as an insulation in natural and synthetic variations up until the 1950s. However, it has since been largely replaced with plastics.

The experts at ESPE Manufacturing fabricate a variety of custom parts and products from electrical insulation material. Check out the list below to see the material options available.

Custom Manufactured Electrical Insulating Materials

Electrical Insulation Material Offerings and Options at ESPE

At ESPE, we utilize a wide range of electrical insulating materials in our custom manufacturing operations. The primary materials we work with are:

  • Formex: Formex is a brand of electrical insulation materials, all of which are made from flame-retardant polypropylene. They are a versatile and cost-effective solution for a variety of applications, ranging from consumer appliances and electronics to commercial data centers to industrial-scale systems.
  • Nomex: Nomex is a line of paper and pressboard insulation products. These meta-aramid polymer materials offer chemical, thermal, and radiation resistance in addition to their electrical insulation properties. They are commonly used in the aerospace, automotive, power generation, and marine industries.
  • Fishpaper/Vulcanized Fibre: Fishpaper is the generic term for electrical grade vulcanized fibre. It is lightweight, easy to work, and resistant to hot and cold conditions. It is often used in the production of components such as bushings, washers, gaskets, and more. Fibre is the generic term for commercial grade vulcanized fibre. It is hard, durable, and chemically pure and offers excellent strength, flexibility, and workability. It is often used in the manufacture of components such as gaskets, insulating plates, and washers.

We also offer a variety of other types and grades of electrical insulating plastics and papers.

ESPE Manufacturing: Your Expert and Partner for Electrical Insulation

Electrical insulation is essential to ensuring electrical and electronic devices, equipment, and systems are safe. However, the type employed depends on the application, with different applications requiring different electrical resistivity and other physical, mechanical, chemical, and thermal properties. While determining which electrical insulating materials are right for your application can be difficult, the experts at ESPE Manufacturing are here to help.

Whether you’re looking for an electrical insulation material supplier or a manufacturer of electrical insulating parts and products, we can meet your needs. To learn more about our material offerings and options, check out our material catalog. To discuss your material or manufacturing needs with one of our experts, contact us or request a quote today.