O-rings
O-ring surface treatments, coatings and lubrication
A surface treatment changes how an O-ring handles and slides without changing the compound underneath. Some are permanent, like a PTFE dry-film coating or chlorination; some are one-time assembly aids, like a silicone or talc tumble; some are cleaning steps, like plasma treatment or a cleanroom wash. Conquest Seal supplies O-rings with the treatment the print names, applied by the compound maker or a coater, and quotes the base compound and the treatment together.
- Permanent
- PTFE film, chlorination, parylenesurvive handling; PTFE film wears in hard dynamic service
- One-time
- Silicone, talc, moly, graphite tumbleassembly aids; rub off
- Cleaning
- Plasma, cleanroom washfor paint shops and chambers
- In service
- Grease matched to the compoundthe compatibility trap
Why treat the surface at all
Bare rubber is tacky. Rings stick to each other in the bag, jam in the bowl of an automated feeder, drag over a thread or a sharp edge on assembly and cut, and in a dynamic gland they grab and release against the metal, the stick-slip that squeals and wears. A surface treatment fixes one or more of those. It also gives a way to tell one compound from another at a glance, since coatings come in colors. None of it changes the compound's temperature range or chemical resistance; the base material page still governs.
The treatments
The table names the treatments the compound makers and coaters offer, what each is for and what it costs you. Thickness, temperature and friction figures are not published here, because they belong to the coater's sheet for the treatment you order; ask for that sheet with the quote.
| Treatment | What it is | What it fixes | Watch for |
|---|---|---|---|
| PTFE dry-film coating | A thin fluoropolymer film sprayed or electrostatically applied and cured on the ring, in clear or colors | Dry, clean lubricity that survives handling; automated feeding; lower assembly force; color identification; less stick-slip in dynamic glands | Can flake or rub through in hard dynamic service; adds nothing to chemical resistance; ask for the coater's sheet |
| Silicone oil or grease tumble | Rings tumbled with a light silicone lubricant | Easy manual assembly; rings slide over threads and edges | One-time; rings cling together in bulk; never on silicone compounds that swell in silicone fluids |
| Talc or micro-talc | A dry powder tumble | Rings stop sticking to each other; cheap assembly aid for static glands | One-time; the powder migrates into clean systems and into the medium |
| Molybdenum disulfide or graphite film | A dry solid-lubricant powder tumbled on, or a bonded dry film | Assembly lubricity and load-bearing lubrication in slow dynamic glands; the bonded film lasts | Tumbled powder rubs off and contaminates; dark films hide the compound color |
| Chlorination (halogenation) | A chemical treatment of the ring surface itself on nitrile and EPDM | A permanently slicker surface with no coating to wear off; automated feeding; less stick-slip | Only on compounds the process suits; the surface, not the bulk, changes; ask the maker |
| Plasma cleaning | A low-pressure plasma treatment that strips contaminants from the surface | Rings free of substances that stop paint wetting (LABS-free) for paint shops and coating lines; residue-free rings for chambers | The result needs the maker's special packaging to survive shipping; it is a cleaning step, not a lubricant |
| Parylene | A vapor-deposited polymer film in several grades | A thin, even barrier against moisture and some chemistry; medical and electronics parts | Applied by a specialist coater; a coated ring is a different part on the print |
| Internal lubrication | A lubricant compounded into the rubber that blooms to the surface over time | A ring that stays slicker through its life without an applied film | Only a small share of the additive reaches the surface; the maker's compound sheet governs |
| Cleanroom wash and double bag | Washing in filtered water and packaging in a clean room | Rings for semiconductor chambers and other clean processes | Order it by name; an ordinary ring is not clean enough for a chamber |
| Color coding | A pigmented compound or a colored coating | Telling compounds apart on the bench and in the kit | Color proves nothing about the compound; the certificate does |
Which treatment for which problem
Match the treatment to the problem rather than to the name. Manual assembly over threads wants a silicone tumble or a PTFE film. Automated bowl feeding wants a PTFE film or chlorination, because talc and silicone gum up feeders. A dynamic gland that squeals wants a PTFE film, chlorination or an internally lubricated compound. A paint shop wants plasma cleaning; a chamber wants a cleanroom wash and ultrapure packaging; a kit with several compounds wants color.
Name the treatment your print calls for and we quote it.
Lubrication in service
A treated ring still usually needs a lubricant at assembly and, in dynamic service, a lubricant that stays. The grease families are silicone, fluorinated, PTFE-thickened and petroleum, and the trap is compatibility: silicone grease swells silicone rings, petroleum grease attacks EPDM, and a grease that suits the ring may not suit the medium. The Parker® O-Ring Handbook carries a lubricant table by compound and application, and the compound maker's sheet names what it approves. Name the lubricant your print or the compound maker approves and we quote it with the ring.
What to put on the order
The base compound and hardness as the print names them, the AS568 dash number or the dimensions, the treatment by name and color if it is a PTFE film, the packaging (bulk, cleanroom, double-bagged) and the quantity. A treated ring is a different part from an untreated one, so say it on every reorder. The quote names the compound, the treatment and the coater's or maker's sheet.
Related pages
Frequently asked
Does a PTFE coating make an O-ring chemically resistant?
No. The film is thin and porous enough that the compound underneath still decides the chemical resistance; the coating is for lubricity, handling and color. Chemistry problems are solved by the compound, or by a PTFE-encapsulated ring.
Which treatment for automated assembly?
A PTFE dry-film coating or chlorination. Both keep rings from sticking to each other and to the feeder without a powder or oil that gums the machine.
Can I get a treated O-ring in a color?
Yes. PTFE dry-film coatings come in a range of colors and clear, and pigmented compounds exist for many families; color identifies the ring but never certifies the compound.
What grease should I use on an O-ring?
One the compound maker approves for the ring and the medium. The trap is silicone grease on silicone rings and petroleum grease on EPDM; the compound maker's sheet names the approved lubricants.
What is a plasma-treated O-ring for?
Paint shops and coating lines that reject parts carrying substances that stop paint wetting (LABS), and clean processes that reject surface residue. It is a cleaning step with special packaging, not a lubricant.
Is chlorination the same as a coating?
No. Chlorination changes the rubber surface itself on nitrile and EPDM rings, so there is no film to wear off; a coating adds a film on top of the compound.
Related guides
Sources
Treatments, in our words from the coaters' and makers' descriptions (NH O-Ring coatings page, JIOrings treatments page, Canyon Components coatings page, Marco Sealing Solutions coatings page, Global O-Ring coating post, a lubricant maker's technical pages; read 2026-09-14); no figure taken; Lubricant table by compound and application (Parker O-Ring Handbook ORD 5700, named, not reproduced). Dimensional facts are stated in our own words; no standard's text or table is reproduced.
Parker is a trademark of Parker Hannifin Corporation. No affiliation or endorsement is implied.
Send the compound and the treatment
The base compound and hardness, the dash number or dimensions, the treatment your print calls for (and its color if it is a PTFE film) and the quantity. A Conquest representative replies with the quote.
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