---
title: "Fibreglass filter bag"
description: "A fibreglass filter bag is woven from glass-fibre yarn, normally finished with a PTFE, silicone or graphite coating to improve flex resistance and dust release. Continuous service rating is up to 260 °C, peaking briefly higher. Fibreglass is the standard bag medium for coal-fired utility reverse-air baghouses and for high-temperature cement-kiln duty."
canonical_url: "https://sylio.co/glossary/fibreglass-filter-bag"
last_updated: "2026-06-28T02:29:24.938Z"
---

A **fibreglass filter bag** is woven from glass-fibre yarn, normally finished with a PTFE, silicone or graphite coating to improve flex resistance and dust release. Continuous service rating is up to 260 °C, peaking briefly higher. Fibreglass is the standard bag medium for coal-fired utility [reverse-air baghouses](/glossary/reverse-air-baghouse) and for high-temperature cement-kiln duty.

## Strengths

- Highest continuous-temperature rating of mainstream media (260 °C)
- Dimensionally stable, low thermal shrinkage
- Compatible with sulphurous flue gas after appropriate coating

## Weaknesses

- Brittle — does not tolerate sharp flexing from aggressive [pulse-jet cleaning](/glossary/pulse-jet-cleaning-cycle); favours [reverse-air](/glossary/reverse-air-baghouse) design
- Limited cleanability — cake can adhere; often paired with a [PTFE membrane](/glossary/ptfe-membrane-filter-bag) overlay for tighter outlet limits
- Hydrolyses below the acid dew point in sulphurous gas

## Acoustic cleaning compatibility

[Sonic horns](/glossary/sonic-horn) installed on a reverse-air fibreglass baghouse supplement the gentle reverse-air cycle without the bag-flex fatigue that would arise from more aggressive primary cleaning. This is a particularly well-suited combination on coal-fired utility duty.

## Related terms

- [Filter bag](/glossary/filter-bag)
- [Reverse-air baghouse](/glossary/reverse-air-baghouse)
- [PTFE-membrane filter bag](/glossary/ptfe-membrane-filter-bag)