PTFE VS MOS₂
HEAD TO HEAD.

They lubricate by different mechanisms

The difference in behaviour comes directly from the difference in physics.

PTFE is a fluoropolymer. Its lubricity comes from extremely low surface energy — the fluorine atoms sheathing the carbon backbone resist bonding to almost anything. Nothing sticks to it, including the mating surface, and that non-stick behaviour is what produces the low friction.

Molybdenum disulphide is a lamellar solid. Its crystal structure is a stack of sheets held together by weak van der Waals forces. Under load those sheets shear across one another like a deck of cards, and that internal shear carries the sliding motion instead of the substrate.

The consequence: PTFE performs by refusing to bond, MoS₂ performs by shearing internally. PTFE loses when heat or pressure overwhelms the polymer. MoS₂ loses when something interferes with the sheets.

Temperature

PTFE runs to roughly 500°F in continuous service. Above that the polymer begins to degrade and the coating loses both its lubricity and its integrity. MoS₂-based coatings run substantially higher — commonly to around 750°F in air — because the limiting factor is the resin binder and the oxidation rate of the MoS₂ itself rather than a polymer softening point.

The 300–500°F band is where the decision gets interesting: it is the top of PTFE's range and the bottom of MoS₂'s comfort zone, and either can work depending on what else the part is being asked to do.

Contact pressure

MoS₂ wins decisively on load. The lamellar shear mechanism actually improves under pressure — higher load aligns the platelets more effectively with the direction of sliding. PTFE has a comparatively low load-carrying capacity and will be extruded out of a high-pressure contact, leaving the substrate exposed.

For heavily loaded sliding contacts, press fits, high-torque threaded joints, and precision bearings, MoS₂ is the default.

Environment — this is the one people get wrong

MoS₂ performs better in vacuum and dry air than it does at atmosphere. With no moisture present, the sheets shear cleanly, which is why it has long been the standard for vacuum and space mechanisms.

In humid air the picture reverses. Water vapour interferes with the shear planes, and over time MoS₂ oxidises to molybdenum trioxide — which is abrasive rather than lubricating. In genuinely wet or humid service, MoS₂ degrades.

PTFE is unaffected by humidity. It is hydrophobic and chemically inert, so wet, washdown, and corrosive environments favour PTFE by a wide margin.

Chemical exposure

PTFE is close to chemically inert and resists nearly everything short of molten alkali metals and elemental fluorine. If the part sees solvents, acids, caustics, or process chemistry, PTFE is the safer specification.

Release and anti-stick

If the requirement is that something must not adhere to the part — moulded rubber, adhesive, resin, food product — PTFE is the only real candidate. MoS₂ reduces friction but has no meaningful release property.

Appearance and film thickness

MoS₂ coatings are dark grey to black. PTFE coatings are available across a wide colour range, which is useful when finished parts need visual identification or when the coating is on a visible surface. Both apply as thin films that add minimal dimension, though exact build depends on the specific product and the number of coats.

Quick selection guide

• High contact pressure, dry or vacuum service, high temperature → MoS₂
• Wet, humid, washdown, or chemically aggressive service → PTFE
• Release or non-stick is the actual requirement → PTFE
• Above 500°F → MoS₂
• Precision bearings and heavily loaded slides → MoS₂
• Food, medical, or colour-coded parts → PTFE

When to combine them

Some formulations blend both solids in a single binder to cover mixed duty cycles — a part that sees high load during a brief actuation but sits in humid ambient conditions the rest of the time, for example. Combination products trade peak performance in either direction for broader tolerance, which is often the right trade when the duty cycle is genuinely mixed.

The mistake worth avoiding

Selecting on coefficient of friction alone. Published friction values are measured under specific test conditions that rarely match your application, and a coating with a lower headline number can still fail early if the environment attacks its mechanism. Load, temperature, and environment decide the outcome. Friction is what you optimise after those three are satisfied.

Not sure which way to go?

Our coating selector walks through material, part type, environment, and goal in four steps and returns a specific recommendation with the reasoning behind it. Or send us a sample batch and we will coat them at no charge so you can test both on your actual parts.

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