How Is Silicone Sponge Manufactured?

Silicone sponge is a lightweight, flexible sealing material manufactured by introducing a cellular structure into silicone rubber. This gives it a combination of silicone's excellent temperature resistance and the softness and compressibility of a sponge material.

Silicone sponge is commonly used for gaskets, seals, doors, enclosures, electrical equipment, ovens, medical equipment and industrial machinery.

Unlike solid silicone rubber, silicone sponge contains a network of small cells that allow it to compress and recover when pressure is applied.

What Is Silicone Sponge?

Silicone sponge is made from silicone rubber that has been processed to create a cellular structure.

Depending on the manufacturing process, silicone sponge can have either an open-cell or closed-cell structure.

Closed-cell silicone sponge generally provides better resistance to the passage of air and moisture.
Open-cell silicone sponge is softer and more compressible and can be useful where cushioning or conformability is required.

The finished material can be produced in different densities, thicknesses, hardnesses and grades to suit different applications.

How Is Silicone Sponge Made?

The manufacturing process can vary depending on the type of silicone sponge being produced, but generally involves several stages.

1. Silicone Compound Preparation

The process begins with a specially formulated silicone rubber compound.

The silicone is mixed with ingredients that provide the required properties, such as:

- Colour
- Hardness
- Density
- Reinforcement
- Flame resistance
- Other specialist characteristics

A suitable blowing or foaming system is also incorporated to create the cellular structure.

2. Mixing

The silicone and other ingredients are thoroughly mixed to create a consistent compound.

Careful control of the formulation is important because it influences the final sponge's:

- Density
- Cell structure
- Hardness
- Flexibility
- Compression characteristics
- Temperature resistance

3. Forming the Sponge

The prepared silicone compound is formed into the required shape.

Depending on the manufacturing method, this may involve extrusion, moulding or calendaring.

For silicone sponge sheet, the material is formed into a continuous sheet before being cured.

For silicone sponge profiles, the compound can be extruded through a specially designed die to create the required cross-section.

4. Expansion and Curing

This is one of the most important stages of silicone sponge manufacturing.

Heat activates the curing and expansion process, causing the material to develop its cellular structure.

The silicone expands while the curing system causes the rubber to cross-link and become stable.

Careful control of temperature, pressure and processing conditions is required to achieve a consistent cell structure and density.

5. Post-Curing

Some silicone sponge materials undergo an additional post-curing process.

Post-curing involves heating the material for a controlled period after the initial manufacturing process.

This can help remove residual volatile substances from the silicone and improve the finished material's stability and performance.

The exact process depends on the silicone formulation and the requirements of the finished product.

6. Inspection and Testing

Once manufactured, silicone sponge can be inspected and tested to ensure it meets the required specification.

Depending on the grade and application, testing may include:

- Density
- Hardness
- Compression characteristics
- Tensile strength
- Elongation
- Temperature resistance
- Dimensional accuracy
- Cell structure
- Compression set
- Specialist grades may also require additional testing or certification.

What Is Silicone Sponge Used For?

The combination of flexibility, compressibility and temperature resistance makes silicone sponge suitable for many applications.

Common uses include:

Gaskets and Seals

Silicone sponge is widely used to manufacture gaskets and seals where a soft, compressible material is required.

It can conform to uneven surfaces and compensate for small gaps between components.

Doors and Enclosures

Silicone sponge seals are commonly used around doors, access panels and enclosures.

They can provide an effective environmental seal while requiring relatively low compression forces.

Electrical Equipment

Silicone sponge can be used around electrical cabinets and equipment to help protect against moisture, dust and environmental contamination.

Ovens and High-Temperature Equipment

Silicone's high-temperature resistance makes silicone sponge suitable for selected oven, heating and industrial applications.

Medical Equipment

Specialist silicone sponge grades can be used in medical and healthcare equipment where particular material properties or certifications are required.

What Are the Advantages of Silicone Sponge?

Silicone sponge offers several useful properties.

Excellent Temperature Resistance

Silicone sponge can maintain its properties across a wide temperature range, depending on the grade.

Highly Compressible

Its cellular structure allows it to compress easily, making it useful where a seal needs to accommodate uneven surfaces or larger gaps.

Flexible

Silicone sponge remains flexible over a wide range of temperatures.

Good Weather Resistance

Silicone provides excellent resistance to ozone, UV exposure and weathering, making it suitable for many outdoor applications.

Long-Term Stability

Silicone generally has good resistance to ageing and can retain its properties for extended periods when correctly specified.

Silicone Sponge Density

One of the most important characteristics of silicone sponge is its density.

A lower-density sponge will generally be softer and easier to compress, while a higher-density sponge will generally provide greater resistance to compression.

The correct density depends on the application.

For example, a door seal may require a soft sponge that can compress with relatively little closing force, while an industrial gasket may require a denser material.

Silicone Sponge vs Solid Silicone

Although both materials are made from silicone rubber, they are designed for different purposes.

Silicone Sponge	Solid Silicone
Cellular structure	Dense rubber
Highly compressible	Less compressible
Lightweight	Higher density
Useful for larger gaps	Useful for thin, precise seals
Commonly used for doors and enclosures	Commonly used for gaskets and sheet seals
Available in different densities	Available in different hardnesses

The correct material depends on the design of the joint and the amount of compression available.

Silicone Sponge Sheet and Profiles

Silicone sponge can be manufactured in both sheet and continuous profile form.

Silicone sponge sheet can be cut into bespoke gaskets and seals, while extruded sponge profiles can be manufactured in a wide range of cross-sections.

This allows silicone sponge to be produced for applications ranging from simple flat gaskets to complex door seals and specialist profiles.

Bespoke Silicone Sponge Gaskets

At TYM Seals & Gaskets, silicone sponge can be supplied as sheet material or converted into bespoke gaskets and sealing components.

Gaskets can be manufactured to:

- Drawings
- CAD files
- Dimensions
- Samples
- Customer specifications

Different silicone sponge grades, densities and thicknesses can be considered depending on the application.

Silicone Sponge from TYM Seals & Gaskets

TYM Seals & Gaskets supplies and manufactures silicone sponge sheet, seals, gaskets and bespoke silicone components for a wide range of applications.

Our silicone materials are used across industries including medical, automotive, electrical, food, engineering and industrial manufacturing.

If you are unsure which silicone sponge material or density you require, provide us with the dimensions, operating temperature, compression requirements and application, and we can help identify a suitable material.

Explore silicone sheet and sponge materials.

Frequently Asked Questions

How is silicone sponge manufactured?

Silicone sponge is manufactured by mixing a silicone rubber compound with ingredients that create a cellular structure. The material is then formed, expanded and cured before being inspected and, where required, post-cured.

What is silicone sponge made from?

Silicone sponge is made from silicone rubber combined with various additives and a blowing or foaming system that creates its cellular structure.

What is the difference between silicone and silicone sponge?

Solid silicone is a dense rubber, whereas silicone sponge contains a cellular structure that makes it softer, lighter and more compressible.

Is silicone sponge waterproof?

Closed-cell silicone sponge can provide good resistance to water and moisture. However, the exact performance depends on the material's cell structure and formulation.

What temperature can silicone sponge withstand?

The temperature range depends on the particular silicone sponge grade. Silicone is generally well suited to both high- and low-temperature applications, but the manufacturer's specification should always be checked for the specific material.