Acoustic fabric and standards: physics and chemistry

Alongside the core characteristics, standards, and technical specifications relating to speaker cloth, sound transparency and frequency response in particular,  possibly also protection against mechanical impact or splash water, and fire safety, there is a whole range of additional standards and parameters which may initially appear secondary, yet still provide valuable information about the suitability and quality of a speaker fabric.


Colour fastness, wash resistance, pilling or dimensional stability may sound more like the language of clothing textiles or upholstery fabrics than loudspeaker construction, acoustic ceilings, home cinemas, or studio interiors. In practice, however, such properties play a decisive role in determining whether an acoustic fabric will still look pristine after several years or begin showing signs of ageing far too early.

After all, speaker fabric has to do considerably more than simply allow sound to pass through unobstructed. It must remain evenly tensioned over time without sagging, be easy to install, resist fading, avoid lint formation, and cope reliably with everyday stresses and environmental influences.
 

Why physical and chemical testing matters

Established textile standards were originally developed primarily for the clothing industry and furniture manufacturing. In those sectors, it is crucial to understand how a fabric reacts to washing, moisture, friction or sunlight. Ultimately, however, many of these requirements also apply to technical textiles such as speaker fabrics. The weighting may differ, and in some respects the criteria are arguably even more important than for garments. Speaker cloth remains under constant tension for years, is exposed to daylight, touched during cleaning and handling, and is expected to retain a clean, high-quality appearance over long periods – especially in premium loudspeaker systems, interior installations, or studio environments.

For this reason, it is well worth taking a closer look at relevant standards and test results. Equally, a degree of scepticism is justified when a supplier provides acoustic specifications only, while offering no indicators regarding long-term stability, everyday durability or harmful substances.
 

Colour fastness during washing and water exposure

One criterion frequently overlooked in acoustic fabrics is colour fastness – in other words, how stable the colour remains when exposed to water, detergents or even perspiration. Numerous standardised test procedures exist for this purpose. Wash resistance, for example, is assessed according to DIN 54014 and its successor standards within the ISO 105 series. These tests evaluate how strongly colour and material properties change under defined washing conditions. Our Standard Speaker Cloth achieves ratings between 4 and 5, which represents a very good result. The scale generally ranges from 1 to 5, with higher values indicating lower colour change and reduced bleeding.

A similar principle applies to colour fastness to water according to EN ISO 105 E01. This test examines how a textile behaves under prolonged exposure to moisture and pressure. Again, our fabric achieves values between 4 and 5, with a rating of 4 for so-called bleeding – the release of excess dye during washing. Although most of our fabrics (with the exception of the flame-retardant FR fabric) can in fact be removed and washed relatively easily when installed using adhesive tape, few people are likely to put their speaker grilles into the washing machine every few weeks. Nevertheless, these test results are far from irrelevant. They provide a reliable indication of how firmly the colour is fundamentally fixed within the material. Fabrics with poor wash fastness values generally also tend to fade or exhibit colour migration more quickly in everyday use.
 

Rub fastness and pilling

Speaker fabric is rarely left completely untouched. It is stretched during installation, handled while cleaning, and may brush against edges during transport. Particularly on loudspeaker fronts or AV furniture, regular mechanical contact occurs simply through people passing nearby. What happens under such conditions – or ideally does not happen – is assessed through rub fastness testing according to DIN 54021. This standard describes procedures for evaluating how strongly a fabric tends to transfer colour under friction, both dry and wet. Our Standard Speaker Cloth achieves values between 4 and 5 for lighter shades, and stable values of 4 for medium and darker colours.
This has direct practical relevance. Fabrics with poor rub fastness often develop shiny worn areas or transfer pigments onto surrounding materials after relatively short periods. Dark fabrics in particular can quickly appear patchy or uneven.

Another common consequence of friction is pilling – the familiar formation of small fibre balls on the surface, frequently seen in inexpensive fabrics. Such pilling rapidly makes textiles appear worn and low-quality. The tendency to pill is tested using the Martindale method, in which fabrics are subjected to controlled abrasion cycles. Our Standard Speaker Cloth achieves values between 4 and 5 in this test, demonstrating very low susceptibility to pilling. In practice, this is especially important for larger fabric surfaces such as AV furniture fronts, wall coverings in home cinemas or studios, and naturally for larger loudspeaker constructions. Even small surface imperfections become immediately visible in such applications and disturb the overall visual uniformity.

Naturally, no standard can fully account for severe mechanical stress caused by curious children or household pets. Few fibre-based materials are truly resistant to claws or sharp objects. In such cases, only sensible design solutions help – for example avoiding fabric coverings on the lower sections of walls or positioning loudspeakers out of easy reach.
 

Dimensional stability and tension behaviour

Speaker fabric must stretch well during installation. At the same time, it must not permanently deform, sag, or shrink afterwards. Here, our elastic jersey fabrics made from pure polyester yarn offer significant advantages over many woven textiles, rigid fabrics, or elastane blends. We discussed this in greater detail in Part 2 of this series, so only a brief summary is needed here: at a load of 30 Newtons, our speaker fabric achieves elongation values of 32% lengthwise and as much as 62% widthwise. This allows clean, crease-free installation around edges and frames. The fabric also performs convincingly in dimensional stability after cleaning. Measured dimensional change is only minus 2% in both length and width – highly controlled behaviour for an elastic textile. In practice, this means the fabric is easy to work with, remains evenly tensioned over tim,e and shows very little tendency towards waves or sagging.
 

UV resistance

EN ISO 105 B02 describes a test method for colour fastness to artificial light, usually using xenon lamps whose spectrum simulates daylight. The assessment measures how strongly a material fades over time. Our Standard Standard Speaker Cloth achieves ratings between 4 and 5 on a scale from 1 to 9. The solution-dyed black acoustic fabric performs even slightly better. These are solid, entirely practical values for conventional indoor applications. In normal living environments, home cinemas, studios, or loudspeaker installations, the colour remains stable over long periods.

At the same time, it is important to state the limitations clearly. Our speaker fabrics were primarily developed for indoor use. Permanent outdoor exposure or extreme UV radiation will, as with almost any textile, eventually lead to fading and material degradation. This applies especially to installations exposed to direct and continuous sunlight. A typical example would be loudspeakers mounted on rear parcel shelves in cars, where extreme temperatures combine with intense UV exposure during summer months.
For such applications, conventional speaker fabric is only suitable to a limited extent. Noticeable fading, particularly in darker colours, must be expected over time. This does not mean the material is fundamentally unsuitable, but lighter shades – ideally white – should be preferred. Dark fabrics may require occasional replacement.
 

Chemical safety and the issue of formaldehyde

Almost everyone has experienced the unpleasant, sharp odour released by certain textiles when unpacked – whether clothing, suitcase linings or speaker fabrics. In the best case, the smell disappears after a few days. In the worst case, it remains indefinitely. Chemical safety is therefore an important issue, not only for clothing but especially for technical textiles used predominantly indoors.

Ideally, such materials should not release harmful substances into their surroundings. Unfortunately, this cannot always be taken for granted. The number of chemicals used in textile processing and finishing is enormous, and not all are harmless. Examples include heavy metal pigments, aromatic and chlorinated hydrocarbons, or methanal – better known as formaldehyde. This allergenic and potentially carcinogenic substance still plays an important role in numerous industrial processes. Formaldehyde does not even need to be used directly during textile production. Since it is also employed in cargo container fumigation and can outgas from transported products, contamination may occur even in otherwise formaldehyde-free yarns and fabrics. This makes reliable testing all the more important.

Our acoustic fabrics are tested for formaldehyde according to the internationally recognised Japanese desiccator method under JIS A 1460:2021. The result: all our fabrics are formaldehyde-free. Our fabrics are furthermore produced in Germany and Austria under strict manufacturing standards. Our partners comply with stringent EU requirements through comprehensive risk assessments and technical documentation in accordance with the EU General Product Safety Regulation, while also complying with REACH regulations and avoiding hazardous substances such as azo dyes and other toxic, carcinogenic or allergenic chemicals.
 

Why these values are not secondary details

Taken individually, many of these standards and tests may appear relatively unspectacular – and none of them alone determines whether a speaker fabric performs acoustically well. For precisely that reason, however, they are often underestimated. A good speaker cloth is not defined solely by acoustic neutrality. It should also install cleanly, remain visually consistent over time, withstand everyday use and, naturally, pose no hidden risks. The conclusion of Part 3 of our series on standards relating to acoustic fabric is therefore straightforward: quality ultimately results from the interaction of many different properties. For that reason, it is worth paying close attention to test results that may initially appear to be little more than technical footnotes.

In the next article, we will shift perspective and examine another question: what can acoustic fabric actively protect against?