Nylon PA

In the polyamide filament family, Nylon PA is specified, supplied as filament, twisted wire bristle and strip brush fill, drawn in round, triangular, cross-shaped, hollow, star-shaped and rectangular sections and set in straight rows, helical, staggered, zoned, wavy and random fill patterns.

Nylon PA is used in custom cleaning brushes for general wet and dry cleaning, conveying, wiping and scrubbing where resilient contact and wear life are both important.

It is usually weighed against Polypropylene PP, PBT and PET Polyester, and the deciding difference is moisture uptake and working temperature rather than anything you can read off the name.

Compare Nylon PA with PP, PBT, PET. Change material when wet stiffness, temperature, chemical resistance, conductivity, particle shedding, or surface marking becomes the limiting factor.

Nylon PA is medium to firm; filament diameter and trim length control bending force, which is why Nylon PA changes brush stiffness through filament diameter, free trim, density, crimp, and contact. Use finer filament and longer trim for conformable contact; use coarser filament, shorter trim, or higher density for stronger displacement or cutting.

Filament-level figures for this grade and the ones it is usually compared to. A finished brush behaves differently again.

The part people get wrong: the same grade can feel soft or aggressive depending on diameter, trim and density. Specify that geometry before the material, or the sample will surprise you.

Nylon PA takes up 0.3–9% by PA grade and conditioning.

PA6 and PA66 absorb moisture; PA610, PA612 and PA12 retain stiffness better in wet service; this moisture response matters in general wet and dry cleaning, conveying, wiping and scrubbing where resilient contact and wear life are both important.

What this means for your application: absorbed water swells the filament and drops contact pressure, so a brush that reached the far end of a bore when dry may stop short once it is wet.

A practical check: soak a sample for an hour and re-measure the trim. If it has moved enough to change the contact band, the grade is wrong for the duty.

Nylon type matters: Nylon 6 is listed at 93°C maximum continuous / 121°C short-term, Nylon 6.6 at 120°C / 180°C, and Nylon 6.12 at 93°C / 121°C. Confirm the exact nylon grade.

Design to that answer rather than to a raw-material datasheet figure: a brush rating already accounts for filament working under load rather than raw polymer sitting in an oven.

Published melting point is 175–265°C by PA grade. That is a material property, not an operating ceiling, and using it to justify a hot wash is the fastest way to ruin a brush.

Where it stops working: validate with a sample if the process sits near the top of that band. If the filament takes a permanent set under load, step up to PET Polyester or PBT, which hold a higher continuous temperature.

The usable limit also moves with diameter, trim and contact pressure. A fine filament under light load tolerates more than a thick one under heavy scrubbing.

It stands up to water, oils, mild detergents and dilute alkalis.

What degrades it: strong mineral acids, phenols and strong oxidizers.

The same cleaner can be harmless or destructive depending on how strong it is, how hot it runs and how long it sits. Quote the concentration and the dwell time, not just the product name.

Before you commit to a quantity: Specify the exact Nylon PA grade or alloy, filament or profile size, color, straight or crimped form, working temperature, wet or dry use, chemical exposure, surface finish, and any required material documentation.

About 0.08 mm. Below that the filament turns fragile and breaks under ordinary contact pressure, so 0.08–2.50 mm is the working range.

Free trim runs 3–300 mm, and the two interact: a finer filament needs a shorter trim to keep useful stiffness, while a thicker one carries a longer trim and still lands pressure on the tip.

Split the range by duty: roughly 0.08–0.68 mm for light wiping, dusting and surfaces that mark easily, and 0.68–2.50 mm where residue is packed on and point pressure matters more than surface risk.

Tip treatments available on this filament: end rounding, tapered-tip grinding, silicone-oil coating, anti-static coating and antibacterial coating.

In practical brush terms: reaching deep into a bore or crevice is a diameter problem before it is a length problem. A thicker filament on a moderate trim pushes further in before the tips fold over.

General wet and dry cleaning, conveying, wiping and scrubbing where resilient contact and wear life are both important.

Where it turns up in practice:

• Industrial Machine Cleaning
• Dust Removal
• Brick, Tile & Building Material Machine Brush Use
• Laboratory Tube Cleaning
• Household Dish, Teapot & Kitchen Detail Cleaning
• Carpet Machine Cleaning

It is normally set into these constructions:

• Custom Handheld Detail Brushes
• Custom Tube & Pipe Bore Brushes
• Custom Roller and Conveyor Brushes
• Custom Polishing Buffing Wheels

If the sample comes back rejected: The nylon family spans several grades, so heat, moisture and chemical limits should follow the selected PA resin rather than a generic nylon value.

A usable specification carries the construction, the filament diameter and free trim, the density and contact setting, and the service conditions: wet or dry, temperature, and what the cleaner actually is.

The mistakes that most often send a sample back:

• Selecting Nylon PA from the material name alone without setting filament diameter, trim length, and density
• Using dry stiffness to predict wet behavior without checking moisture absorption or liquid exposure
• Ignoring trapped abrasive particles, chemical concentration, temperature, or contact motion when assessing surface risk

Reference standards behind the figures on this page: ISO 527-1:2019; ASTM D638; ISO 62:2008; ASTM D570-22; ISO 868:2003; ASTM D2240-15(2021); ISO 4892-3:2024; ASTM G154-23; UL 94.

Source: American Brush Manufacturers Association — Brush Lingo — Synthetic Filaments. Brush-industry limits vary by nylon type; do not use a generic nylon melting point as a service limit.