Quick Answer
Every other brush on this site removes something. A seal brush holds a barrier: it fills a gap that has to stay closed against dust, draught, light, chips or insects while a door, a belt or a cable moves through it. That makes it a wear component with a service life, and the specification is dominated by the gap, the movement and whatever certificate the assembly around it has to carry.
What the Gap Has to Do
- Hold contact while something moves — a door leaf, a sliding guard, a conveyor edge. Free trim length has to exceed the gap by enough to stay in contact through the whole travel, including wear.
- Let something pass without damage — cables through an entry, product across a guard opening. The fill must part and recover rather than abrade what goes through it.
- Contain, not seal absolutely — a brush seal is a barrier, not a gasket. Where a true seal is required, this is the wrong component and no fill choice fixes that.
- Carry the assembly rating — fire, smoke, static or hygiene requirements belong to the assembly the strip sits in, and they govern the fill before the dust does.
Filament by Duty
| What the seal faces | Where to start | Why |
|---|---|---|
| Ordinary dust and draught, indoors | Nylon PA or PBT | recovers after millions of cycles at low cost |
| A fire or smoke rating on the assembly | Flame Retardant Nylon | the certificate governs the fill; nothing else on this list overrides it |
| Static-held dust, or an ESD-controlled room | Conductive Nylon or Anti-Static Filament | discharges rather than merely resisting charge, where a grounding path exists |
| Combustible dust in a protected area | Conductive Nylon with a measured bond | in these areas the bond is the specification, not the fill name |
| Outdoor, UV and weather | Polypropylene PP, UV-stabilised | holds its strength through seasons where untreated fill chalks |
| Wet or washdown service | Polypropylene PP or PBT | takes up no water, so the trim length does not change with humidity |
Construction and Mounting
The holder decides most of the installed cost: an aluminium or galvanised channel screwed to the frame, a clip-in profile, or a brush strip wound into a spiral for a rotating opening. Density is the second lever — the same fill at higher density seals better and wears faster, and on a moving leaf it also adds drag. Where the brush must survive being cleaned, the holder material is chosen with the fill, not after it.
Where It Goes Wrong
- Ordering by the gap and not by the travel. A strip sized to the closed gap loses contact as soon as the leaf moves or the frame settles.
- Buying a brush seal to do a gasket’s job. It contains; it does not seal.
- Choosing an antistatic fill for an area that needs a discharge path. Antistatic and conductive are not the same claim, and only one of them is measurable at the bond.
- Ignoring the certificate on the assembly. A correct fill inside a non-compliant strip fails the inspection anyway.
What to Send for a Quote
The gap and its tolerance, the travel and cycle rate, what passes through, the holder profile or the frame it screws to, the environment, and any fire, smoke, hygiene or static requirement the assembly carries. Say whether the strip is cut to length on site or supplied finished.
Which bristle material fits this job — Nylon PA, PBT or Polypropylene PP?
| Material | Continuous temperature (°C) | Peak temperature (°C) | Water absorption | Hardness |
|---|---|---|---|---|
| Nylon PA | 93 | 121 | 0.3–9% by PA grade and conditioning | Medium to firm; filament diameter and trim length control bending force. |
| PBT | 120–140 | 160–180 | 0.05–0.20% | Shore D 80–90 |
| Polypropylene PP | 80–100 | 120–140 | ≤0.03% | Shore D 65–75 |
| Flame Retardant Nylon | 150 | 180 | 1–8% by PA grade | Set by the specific grade, reinforcement and additive package; compare with ordinary filament through sample testing. |
| Conductive Nylon | 80–110 | 130–160 | 0.5–2.5% | Shore D 75–88 |
Figures as published by Brushtec / DuPont; Perlon. Confirm the exact grade against the supplier datasheet before ordering.
When are Strip Seal Brushes the wrong choice?
- Strip Seal Brushes — Use rubber lips, foam, labyrinth seals, air curtains, or rigid scrapers when pressure sealing or liquid containment is required.
- Roller and Conveyor Brushes — Use a stationary strip brush for a fixed linear seal or wipe, or another process when rotating line contact interferes with the product or cannot discharge the residue safely.
- Nylon PA — The nylon family spans several grades, so heat, moisture and chemical limits should follow the selected PA resin rather than a generic nylon value.
- PBT — Not for heavy rust removal or high-cutting deburring.
What should replace Strip Seal Brushes when they stop working?
- Strip Seal Brushes — Strip brushes create a linear barrier or guide; machine-table brush plates distribute load and support products over a broad area. Closest alternative: Machine Table Brush Plates.
- Roller and Conveyor Brushes — Roller and conveyor brushes hold cylindrical line contact across a working width, including helix-wound builds where the filament path is set to move loosened material toward one side; a strip brush holds the same line without rotating, so it seals or wipes but cannot carry residue along the width.
- Nylon PA — 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.
- PBT — Compare PBT with Nylon, PP, PET. Change material when wet stiffness, temperature, chemical resistance, conductivity, particle shedding, or surface marking becomes the limiting factor.