PET Polyester

In the polyester filament family, PET Polyester is specified, supplied as filament, drawn in round, triangular, cross-shaped, hollow and star-shaped sections and set in straight rows, helical, staggered, zoned and wavy fill patterns.

PET Polyester is used in custom cleaning brushes for outdoor washing, carpet agitation, brush plates and general cleaning where weathering and low water uptake are useful.

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

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

PET Polyester is medium to firm; filament diameter and trim length control bending force; PET Polyester 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.

PET Polyester takes up 0.10–0.30% (24h, ISO 62/ASTM D570).

Low water absorption keeps filament stiffness stable in wet cleaning.

What this means for your application: moisture uptake is low enough to ignore in service, which is why this grade holds its stiffness through washdown.

A practical check: run one wet cycle and compare tip contact against the dry state. If the wet brush leaves residue behind or no longer reaches the bottom of the bore, change the material rather than the geometry.

Grade-dependent. Industrial brush suppliers publish maximum operating guidance around 100–140°C for polyester brush filaments. Confirm the actual PET grade and sustained-load conditions.

The filament tables quote 120–150°C continuous and 170–190°C peak. The tighter number above is the one to build to, because a brush is loaded while it is hot.

The melting point of 250–260°C is not a service limit and should never be used to set a wash temperature. It is the point at which the filament stops being a solid at all.

Where it stops working: validate with a sample if the process sits near the top of that band. A permanent bend under load means the answer is a higher-temperature filament family, not a heavier trim.

Diameter, trim length and applied load all shift the real limit, so a thin filament touching lightly survives conditions that would flatten a thick one under pressure.

It stands up to water, oils, mild acids, alkalis, alcohols and common cleaning solvents.

Compatibility is a function of concentration, temperature and contact time together. A short rinse in a dilute solution is a different exposure from an overnight soak in a concentrated one, even with the same chemical on the label.

Before you commit to a quantity: Specify the exact PET Polyester 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.

The floor is roughly 0.04 mm; finer than that and the filament snaps rather than flexes. In practice you are choosing inside 0.04–1.50 mm.

Free trim runs 3–250 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 0.04–0.4 mm for light wiping, dusting and surfaces that mark easily, and 0.4–1.50 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.

Outdoor washing, carpet agitation, brush plates and general cleaning where weathering and low water uptake are useful.

Where it turns up in practice:

• Industrial Machine Cleaning
• Carpet Machine Cleaning
• Floor Scrubbing
• Brick, Tile & Building Material Machine Brush Use
• CPAP Hose Cleaning
• Laboratory Tube Cleaning

It is normally set into these constructions:

• Custom Tube & Pipe Bore Brushes
• Custom Floor Scrubber Sweeper Brushes
• Custom Roller and Conveyor Brushes
• Custom Machine Table Brush Plates
• Custom Handheld Detail Brushes

The trade-off: Avoid heavy metal deburring or high-temperature wire-brush jobs.

Send the brush type, filament diameter, free trim length, density, contact setting, wet or dry duty, working temperature and the actual cleaning chemistry together. Any one of them on its own leaves the stiffness undefined.

What usually goes wrong at this step:

• Selecting PET Polyester 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; ISO 13061-1; ASTM D143.

Source: American Brush Manufacturers Association — Polyester / PET brush-filament temperature guidance. Different suppliers publish different limits, so grade-specific confirmation is required.