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. 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, chlorinationsurvive handling; PTFE film wears in hard dynamic service
- One-time
- Silicone, talc, moly tumbleassembly aids; rub off
- 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 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 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 | 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 |
| 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 |
| 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 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 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.
Is chlorination the same as a coating?
No. Chlorination changes the rubber surface itself, so there is no film to wear off; a coating adds a film on top of the compound.
Related guides
Sources
Parker O-Ring Handbook ORD 5700, 2021 printing, sections 3.1.5.3 to 3.1.5.5, page 3-5; Parker O-Ring Division Europe, ParCoat Coatings and Surface Treatment Processes, ODE 5001 GB 04/2007; Hutchinson Precision Sealing Systems, Surface Treatments brochure 05/2022 (the treatments, described in our words; no figure taken); Parker O-Ring Handbook ORD 5700, lubricant table by compound and application (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.
Setting Conquest Seal up as a supplier?
Orders are handled under Conquest Seal's AS9100D quality management system, whose certificate scope includes distribution.
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. Quotes answered within one business day. A person answers (714) 632-9830, Pacific business hours.
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