Short answer: Rilsan is Arkema's brand of polyamide 11, also called nylon 11 or PA11. It is made from castor oil and applied to metal as a powder that melts into a thick, tough plastic skin. It protects parts from impact, abrasion and corrosion, and it stays tough at −40 °C. It goes on either by dipping a hot part in a fluidised bed of powder or by electrostatic spray, and the right method depends on the part.
Rilsan turns up in specifications for valves, pipe fittings, handles, shafts and outdoor hardware, and in the coatings on dishwasher baskets and supermarket trolleys. Engineers and buyers meet the name, but the details are scattered across supplier data sheets. This guide covers what Rilsan is, how it is applied, where it works and where another coating is the better choice.
What is Rilsan?
Rilsan is a trade name of Arkema, the French chemicals group, for polyamide 11. Polyamide is the chemical name for nylon, so Rilsan, nylon 11, PA11 and polyamide 11 all mean the same polymer. It is made from castor beans rather than oil or gas, which makes it one of the few engineering plastics that is fully bio-based.
As a coating, Rilsan is supplied as a fine powder. The powder is applied to a clean, hot metal part, where it melts and flows into a continuous skin. Because it is a thermoplastic, it does not cure like paint; it melts, wets the metal and sets as it cools.
What Rilsan does well
- Impact resistance: it takes knocks without chipping and stays tough in the cold, down to −40 °C.
- Abrasion resistance: it holds up to sliding, dragging and handling wear.
- Corrosion protection: a thick, continuous film keeps water and salt off the metal.
- Chemical resistance: it generally resists fuels, oils, alkalis, mineral salts, most solvents and organic acids.
- Electrical insulation: it has high dielectric strength.
- Feel: it gives handles and grips a warm, non-slip surface.
Where Rilsan is the wrong choice
- Continuous heat above about 120 °C. A fluoropolymer such as PFA handles 260 °C.
- Strong mineral acids, phenols and some chlorinated solvents. Halar or Tefzel linings are built for that duty.
- Non-stick release. Nylon is tough but it is not a release surface; PTFE and PFA are.
- Thin, precise films on bearings or fasteners. A dry-film lubricant such as Xylan is a few tens of microns thick.
How Rilsan is applied: fluidised bed vs electrostatic spray
Arkema makes different powder grades for different methods. The two that matter for industrial parts are:
Fluidised-bed dipping. The part is heated well above the powder's melting point and lowered into a tank of powder kept moving by air. Powder melts onto every surface it touches. It is fast and cheap for high volumes of similar parts, such as wire baskets and racks. The limits are the size of the tank and the fact that everything dipped gets coated.
Electrostatic spray. The powder is charged and sprayed onto the part, then melted in an oven. Spraying lets the applicator mask threads, seats and machined faces, coat one side only, and handle parts far larger than any dip tank. Built up on a preheated part in several passes, electrostatic spray reaches the same thick films as dipping.
| Fluidised-bed dip | Electrostatic spray | |
|---|---|---|
| Best for | High-volume wire goods, baskets, racks | Valves, spools, shafts, handles, large or one-off parts |
| Part size | Limited by the tank | Limited by the oven (at AST, 7 m) |
| Masking | Difficult | Straightforward |
| Typical film | 250–500 µm | 80–150 µm single pass; 300–500 µm built up on preheated parts (AST) |
What Rilsan is used for
Arkema reports Rilsan in use on water-industry valves, flanges and couplings since 1967. Other common uses:
- Valve bodies, gates, flanged fittings and couplings for water, wastewater and process service
- Pipe spools and fabricated pipework
- Handles, grips, levers and tool handles
- Shafts, splines and conveyor rollers
- Frames, brackets and materials-handling hardware
- Marine and outdoor hardware
- Dishwasher baskets and wire racks (usually fluidised-bed dipped)
Nylon 11 vs nylon 12
Both are polyamide coatings and they look alike once applied. Nylon 11 is made from castor oil; nylon 12 is made from petrochemicals. Specifications for water, marine and impact duty often name PA11 because of its long track record in those uses. If your drawing says PA11 or Rilsan, a PA12 powder is a different material, so check with the specifier before accepting a substitute.
Food contact and drinking water
Approvals belong to specific powder grades, not to Rilsan as a whole. Arkema lists grades approved for drinking water in several countries, including Australia's AS/NZS 4020, and some grades are approved for food contact. Many of the approved grades are fluidised-bed grades. If your part touches food or potable water, say so when you ask for a quote, so the coater can confirm the exact grade and its approval before work starts.
How long does Rilsan last, and can it be recoated?
Service life depends on what the part does: the impacts it takes, the chemicals and temperatures it sees, and how thick the coating is. Thicker films last longer under wear. When a coating is worn or damaged, the old nylon can be burnt off, the part grit blasted back to clean metal and a new coat applied. For a valve body or a machined shaft, recoating is usually far cheaper than replacement.
Rilsan coating at AST
AST applies Rilsan by electrostatic spray at 300–500 µm as standard and up to 1 mm, in ovens that take parts up to 7 m long. We mask what must stay bare and we also apply the full Chemours fluoropolymer range, so the recommendation follows the duty. For high-volume wire goods we will point you to a dip shop. See our Rilsan nylon 11 coating service for specifications, or send us your part for a quote.