When Should You Use Filled PTFE Instead of Virgin PTFE?

Published on September 29 2026

PTFE is well known for its exceptionally low friction, excellent chemical resistance and wide operating temperature range. These properties make virgin PTFE a useful material for seals, bearings, slide bearing components and many other demanding engineering applications.

But virgin PTFE is not always the best choice.

When a component needs greater wear resistance, load-bearing capability, dimensional stability or resistance to deformation, a filled PTFE grade may provide a better solution.

Filled PTFE is produced by incorporating a reinforcing or performance-enhancing filler into the PTFE resin. Different fillers change the behaviour of the material, allowing engineers to select a grade that is better suited to a particular operating environment.

The important point is that filled PTFE is not simply “stronger PTFE”. Each filler changes the material's properties in different ways, and the right choice depends on the application.

Table of Contents

What is filled PTFE?

When should you use virgin PTFE?

When should you use filled PTFE?

Fluorocarbon PTFE grades

Virgin PTFE vs filled PTFE

FAQ's

When should you use filled PTFE instead of virgin PTFE?

What is filled PTFE?

Virgin PTFE consists primarily of PTFE resin without reinforcing fillers.

Filled PTFE contains PTFE combined with materials such as:

• Glass fibre
• Carbon
• Graphite
• Bronze
• Molybdenum disulphide (MoS₂)
• Ekonol^® and other polymer fillers
• Proprietary combinations of fillers

Fluorocarbon's Fluorinoid^® range includes a wide selection of filled PTFE compounds developed for different combinations of wear, creep resistance, mechanical strength, friction and load-bearing performance.

The filler is selected to improve particular properties of the PTFE.

Depending on the formulation, this can include improved:

• Wear resistance
• Compressive strength
• Stiffness
• Dimensional stability
• Load-bearing capability
• Resistance to creep and deformation
• Thermal conductivity
• Friction and wear characteristics

The trade-off is that adding a filler can also change some of PTFE's original characteristics.

For example, a filled grade may have better wear resistance but a higher coefficient of friction than virgin PTFE. It may also have different chemical, electrical or purity characteristics.

This is why the correct question isn't simply “Is filled PTFE better than virgin PTFE?”

It is:

“Which PTFE formulation provides the right balance of properties for this application?”

When should you use virgin PTFE?

Virgin PTFE is often the preferred choice when its inherent properties are more important than improved mechanical performance.

Fluorocarbon FL100 – Virgin PTFE

Fluorinoid^® FL100 is Fluorocarbon's virgin PTFE material. It offers excellent chemical resistance, very low friction, electrical insulation and high thermal stability. It is available in four grades with different levels of tensile strength and elongation.

FL100 can be particularly suitable where you need:

Excellent Chemical Resistance

PTFE has outstanding resistance to a wide range of chemicals and aggressive media.

Where chemical compatibility is the primary requirement and the component isn't subjected to particularly high mechanical loads or severe wear, virgin PTFE can be an excellent choice.

Very Low Friction

One of PTFE's defining characteristics is its low coefficient of friction.

For applications where minimising friction is the main objective, virgin PTFE can offer advantages over some filled formulations.

High Purity

Some applications require a material with minimal contamination or extractables.

Where purity is critical, the filler itself may introduce limitations, so an appropriate virgin PTFE grade may be preferred.

Non-stick and Release Properties

Virgin PTFE provides excellent release characteristics, making it useful for coatings and components where preventing adhesion is important.

Electrical Insulation

Virgin PTFE also has excellent electrical insulating properties, which can be important in electrical and electronic applications.

When should you use filled PTFE?

Filled PTFE becomes particularly useful when the component is exposed to mechanical loads, friction or wear that could push virgin PTFE beyond its practical limits.

1. When Creep is a Concern

PTFE can gradually deform when subjected to a sustained load. This behaviour, known as creep, can become more significant with increasing temperature and stress.

A suitable filler can improve resistance to deformation and help the component maintain its dimensions under load.

This can be particularly important for:

• Seals
• Bearings
• Valve components
• Bushes
• Slide plates
• Load-bearing components

For example, Fluorocarbon's FL129 reinforced PTFE is used in Fluoroglide^® slide-bearing applications where increased load-bearing capability is required. FL100 has a typical bearing pressure capacity of around 7 N/mm² in specified configurations, compared with around 14 N/mm² for FL129.

^{*These figures are application-specific rather than universal material ratings. Temperature, geometry, containment, counterface and duration of loading all affect the actual allowable load.}

2. When Wear Resistance is Important

Virgin PTFE has low friction, but it isn't always the best choice for severe wear applications.

Adding an appropriate filler can significantly improve resistance to wear.

This makes filled PTFE useful for applications involving:

• Continuous sliding
• Reciprocating movement
• Rotating components
• High contact loads
• Repeated cycles

The correct formulation depends on the load, speed, temperature and mating surface.

3. When the Component Carries a High Load

Virgin PTFE has relatively low stiffness and compressive strength compared with many engineering polymers.

A suitable filler can improve its mechanical properties and make it more suitable for load-bearing applications.

This is one reason filled PTFE is widely used in bearings, wear components and structural sliding elements.

Fluorocarbon's FL129 reinforced PTFE is used in high-load Fluoroglide^® applications, while newer materials such as FL830 have been developed for particularly demanding high-pressure bearing applications where traditional PTFE compounds may not provide sufficient compressive strength.

4. When Dimensional Stability is Important

Temperature changes and sustained mechanical loading can cause dimensional changes in PTFE.

Filled grades can offer improved dimensional stability, which can be valuable where components need to maintain relatively tight tolerances during service.

This is particularly important for precision-machined components and assemblies where excessive deformation could affect clearances or alignment.

Which Fluorocarbon PTFE grade should you choose?

There is no single “best” PTFE filler.

Fluorocarbon's Fluorinoid^® range includes grades formulated for different combinations of friction, wear, creep resistance, load-bearing capability and mechanical performance.

FL100 – Virgin PTFE

Best suited to: applications where chemical resistance, low friction, purity or electrical insulation are the primary requirements.

FL100 is Fluorocarbon's virgin PTFE grade. It provides excellent chemical resistance and very low friction, but is more susceptible to creep and abrasion than many filled grades.

FL103 – Glass fibre-filled PTFE

Best suited to: applications requiring improved mechanical performance and resistance to deformation.

Fluorocarbon's proprietary FL103 is a glass fibre-filled PTFE material with Airbus approval, making it particularly relevant to aerospace applications where material qualification and traceability are important.

FL105 – Glass-filled PTFE

Best suited to: applications requiring improved mechanical strength, wear resistance and resistance to deformation.

FL105 glass-filled PTFE is often considered where the component needs greater mechanical stability than virgin PTFE can provide.

FL114 – Carbon/graphite-filled PTFE

Best suited to: bearing and wear applications.

FL114 combines carbon and graphite fillers to provide good bearing performance with excellent resistance to wear and creep.

FL115 – Carbon-filled PTFE

Best suited to: bearing applications where wear and creep resistance are important.

FL115 is carbon-filled PTFE grade bearing material with excellent resistance to wear and creep.

FL117 – Ekonol^® filled PTFE

Best suited to: applications requiring improved physical properties where the mating surface is not hardened.

FL117 uses a polymer filler to improve physical properties and can be used against non-hardened running surfaces.

FL123 – Graphite-filled PTFE

Best suited to: bearing applications where lubrication is limited.

The graphite filler on FL123 provides a useful combination of low-friction and wear characteristics for selected bearing applications.

FL141 – Bronze-filled PTFE

Best suited to: bearing applications requiring improved wear and creep resistance.

FL141 is a standard bronze-filled bearing material with excellent resistance to wear and creep.

FL148 – Bronze-filled PTFE

Best suited to: oil hydraulic applications.

FL148 is a bronze-filled PTFE grade offering good wear and creep resistance. Because the filler is bronze, however, its chemical resistance needs to be considered in relation to the operating environment.

FL151 – PTFE with special additives

Best suited to: general-purpose low-friction applications requiring improved abrasion and creep resistance.

FL151 provides a balance of low friction with improved resistance to abrasion and creep.

FL156 – Carbon-filled PTFE

Best suited to: applications requiring wear and creep resistance under load.

FL156 is a carbon-filled PTFE formulation developed for improved wear and creep performance under loading.

FL158 – Glass/MoS₂-filled PTFE

Best suited to: demanding applications requiring improved physical properties, creep resistance and abrasion resistance.

FL158 combines glass and molybdenum disulphide fillers. The formulation provides good resistance to creep and abrasion, although a harder running surface may be required to minimise counterface wear.

FL159 – Glass-filled PTFE with special additives

Best suited to: applications requiring improved physical properties, abrasion resistance and creep resistance.

FL159 combines glass fibre with other fillers to provide a general-purpose reinforced PTFE grade with improved mechanical and wear performance.

Virgin PTFE vs filled PTFE

The choice can be simplified by considering what the component needs to do.

Requirement	Virgin PTFE	Filled PTFE
Very low friction	Excellent	Excellent to very good, depending on filler
Chemical resistance	Excellent	Depends on filler and formulation
Wear resistance	Good	Generally improved
Creep resistance	Limited	Generally improved
Load-bearing capability	Limited	Improved
Compressive strength	Lower	Generally higher
Dimensional stability	Lower	Generally improved
High-purity applications	Often preferred	Depends on filler
Electrical insulation	Excellent	Depends on filler
Thermal conductivity	Low	Can be improved

^{These are general comparisons. The performance of an individual PTFE grade can vary considerably depending on its formulation.}

FAQs

Is filled PTFE always better for bearings?

No.

A bearing application needs to be assessed based on the PV conditions, the combination of pressure and sliding velocity, as well as temperature, mating material, surface finish, lubrication and required service life.

Virgin PTFE can be suitable for some low-load or low-wear applications.

For higher loads or more demanding sliding conditions, a filled PTFE grade may offer significantly better wear and deformation resistance.

For example, Fluorocarbon uses both virgin and reinforced PTFE in Fluoroglide^® bearing systems, with FL100 used for standard bearing applications and FL129 used where increased load-bearing capability is required.

However, the filler needs to be selected carefully.

A formulation that performs well against one mating material may not be the best choice against another. Similarly, a filler that improves wear resistance may increase friction.

Bearing material selection should therefore be based on the complete tribological system, not just the polymer.

Is filled PTFE better for seals?

It depends on the seal and operating conditions.

For some seals, virgin PTFE provides the combination of chemical resistance and low friction required.

For others, particularly where there is high pressure, continuous loading or significant extrusion risk, a filled PTFE grade may provide improved resistance to deformation and wear.

Fluorocarbon's sealing materials include grades such as FL114, FL148, FL151 and FL159, selected according to the application and sealing conditions.

Factors to consider include:

• Pressure
• Temperature
• Static or dynamic operation
• Chemical compatibility
• Seal geometry
• Clearance
• Mating surface
• Cycling frequency
• Required service life

In high-pressure applications, creep and extrusion need to be considered together.

What are the disadvantages of filled PTFE?

Adding a filler improves some properties but can reduce or alter others.

Depending on the filler, filled PTFE may have:

• Higher friction than virgin PTFE
• Different chemical compatibility
• Reduced purity
• Different electrical properties
• Greater hardness
• Different machining characteristics
• Different thermal expansion behaviour

Some fillers can also increase the abrasiveness of the material, which may need to be considered when selecting the mating surface.

For example, FL158 requires harder running surfaces to minimise wear because of its glass/MoS₂ filler system.

This is why simply specifying “filled PTFE” isn't enough.

The grade and formulation matter.

How do you choose the right PTFE grade?

Start with the application rather than the material.

Consider:

Temperature

What are the minimum, maximum and continuous operating temperatures?

Pressure and Load

What stress will the component experience, and for how long?

Movement

Is the component static, rotating, reciprocating or sliding?

Wear

How much movement and contact will the component experience throughout its service life?

Chemical Exposure

What gases, liquids, chemicals or process media will the material encounter?

Friction

Is minimising friction more important than maximising wear resistance?

Dimensional Stability

How much deformation can the component tolerate?

Purity

Are there semiconductor, pharmaceutical, food or other contamination requirements?

Electrical Properties

Does the material need to remain electrically insulating or conductive?

Manufacturing

Will the component be moulded, machined, etched or manufactured using another process?

Once these requirements are established, the material formulation can be selected accordingly.

Virgin PTFE isn't necessarily the starting point

A common approach is to begin with virgin PTFE and then move to a filled grade if the application demands improved mechanical performance.

In reality, material selection should start with the application requirements.

If a component needs to carry a continuous load, resist wear and maintain tight dimensions, it may make sense to investigate filled PTFE from the outset.

If chemical resistance, purity and minimum friction are the dominant requirements, virgin PTFE may be the better option.

And if the operating conditions exceed what PTFE can reasonably provide, another engineering polymer such as PEEK, PAI or PI may be more appropriate.

So, when should you use filled PTFE instead of virgin PTFE?

Filled PTFE is generally worth considering when you need to improve wear resistance, load-bearing performance, creep resistance or dimensional stability.

Virgin PTFE may remain the better choice when chemical resistance, very low friction, purity, electrical insulation or non-stick performance are the primary requirements.

Fluorocarbon's Fluorinoid^® range includes virgin PTFE, glass filles, carbon filled, graphite filled, bronze filled and other specialised filled formulations, allowing the material to be selected around the specific requirements of the application.

There is no universal best PTFE grade.

The right formulation depends on the complete application, and sometimes the best solution isn't PTFE at all.

Need help selecting a PTFE grade?

Fluorocarbon manufactures a wide range of PTFE compounds and engineered polymer materials for demanding applications.

Our technical team can help assess the load, temperature, pressure, friction, wear, chemical environment and dimensional requirements of a component before recommending a suitable material or grade. Where an appropriate grade doesn't exist we can formulate a new one. 

From virgin PTFE to filled formulations and alternative high-performance polymers, the objective is to select a material that delivers the required performance throughout the life of the component.

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