The short answer
Nylon 12 absorbs very little water, stays dimensionally stable, is tough in the cold and resists fuels and road salt, so it suits tubing, lines and parts in wet or salty service. Nylon 6 is stronger, stiffer, more heat resistant and much cheaper, so it suits gears, housings and structural parts.
Nylon 12 is the go-to "long-chain" nylon when moisture swelling or chemical cracking rules out nylon 6 or 66. It costs much more, so it is used where those properties are needed.
Side by side
| Property | Nylon 12 (PA12) | Nylon 6 (PA6) |
|---|---|---|
| Density | ~1.01–1.02 g/cm³ | ~1.13 g/cm³ |
| Melting point | ~178°C | ~220°C |
| Water absorption, saturation | ~1.5% | ~9–10% |
| Water absorption, 50% RH | ~0.7% | ~2.5–3% |
| Tensile strength (dry) | ~45–55 MPa | ~75–85 MPa |
| Flexural modulus (dry) | ~1.2–1.5 GPa | ~2.5–2.8 GPa |
| Dimensional stability | Very good | Changes with humidity |
| Low-temperature impact | Very good | Fair (dry) |
| Fuel, oil and salt resistance | Excellent, including zinc and calcium chloride | Good to oils; can stress-crack in road-salt chlorides |
| Relative cost | Much higher | Lower |
| Typical uses | Fuel and brake tubing, pneumatic lines, cable sheathing, 3D printing powder | Gears, housings, glass-filled structural parts, film, fiber |
Typical values for unfilled, unplasticized grades. Plasticized nylon 12 tubing grades are more flexible; glass-filled nylon 6 is much stiffer.
Choose nylon 12 when
- Parts must hold size in humid or wet service
- Fuels, oils, greases or road salt are present
- Flexible tubing or cold-weather toughness is needed
- Fuel, brake, pneumatic and hydraulic lines
Choose nylon 6 when
- Strength, stiffness and heat resistance matter
- Cost is a key driver
- Glass-filled structural parts are the goal
- Gears, housings, brackets, clips
See also nylon 6 vs. nylon 66, nylon parts swelling or changing size and acetal vs. nylon.
Grades we source
We source nylon 11 and 12 (rigid, plasticized and tubing grades) and nylon 6 (unfilled, impact-modified and glass-filled), with a COA on every lot, tested to ASTM or ISO methods. See nylon 11 and 12 and nylon 6 and 66.
Common questions
What is the difference between nylon 12 and nylon 6?
Nylon 12 absorbs far less moisture, so its size and properties stay steady in humid conditions, and it resists fuels, oils and road salt better. Nylon 6 is stronger and stiffer when dry, melts higher and costs much less.
Does nylon 12 absorb water?
Very little compared with other nylons: roughly 1.5% at saturation, versus about 9% or more for nylon 6 immersed in water.
Is nylon 12 stronger than nylon 6?
No. Dry nylon 6 has higher tensile strength and stiffness. Nylon 12 is more flexible and tougher in the cold, and it keeps its properties more consistently as humidity changes.
Why is nylon 12 used for fuel and air brake lines?
It is flexible, tough at low temperatures, absorbs little moisture and resists fuels, oils, greases and road salt, so tubing stays dimensionally stable and resists cracking.
Is nylon 12 the same as nylon 11?
They are close. Both are low-moisture, flexible nylons used for tubing and coatings. Nylon 11 is made from a castor-oil-based monomer; nylon 12 is petrochemical. Grades are often interchangeable after testing.
Can nylon 12 replace nylon 6?
Where moisture swelling or salt cracking is the problem and the part does not need nylon 6's stiffness or heat resistance, often yes. Expect a higher resin cost.
Tell us the grade you run now
A polymer chemist reviews every request, then matches your grade or finds a qualified equivalent and prices it.
What to send for an accurate quote
- The grade name, from any supplier, or a data sheet
- Color (natural, black or a custom match)
- Fill type and percentage, if any
- Melt flow, if you know it
- Quantity for this order and what you use in a year
- Ship-to city and state or province