What Is Modal?

How is modal made?

Modal is made by turning wood pulp into regenerated cellulose fibre through a modified viscose process, tuned so the fibre is stronger and resists stretching when wet. EU law defines it as a fibre from a modified viscose process with a high breaking force and high wet modulus.

The raw material is the wood pulp also used for ordinary rayon (viscose). According to CAMEO, the materials database of the Museum of Fine Arts, Boston, changes to spinning conditions, chemical solutions and stretching sequences raise the fibre’s crystallinity and strength. Cornell Cooperative Extension describes high-wet-modulus (HWM) rayon the same way: viscose rayon modified to increase its wet strength.

Textile Exchange states that Lenzing’s TENCEL™ Modal fibres are made from beech wood grown in PEFC-certified European forests.

A short history

CAMEO traces strengthened rayons to the 1930s, when they were developed for industrial uses such as tyres, conveyor belts and hoses. The high-wet-modulus fibre that modal belongs to was developed in Japan in 1951: CAMEO credits S. Tachikawa and names that fibre polynosic, and Textile Exchange also dates the first HWM modal fibres to Japan in 1951. Textile Exchange states that Lenzing started selling modal fibres in 1964.

Cornell Cooperative Extension describes Modal as the brand name under which Lenzing markets HWM rayon, while CAMEO and EU law treat modal as a generic fibre name.

What are the properties of modal?

Modal is strong, soft and stable when wet, and that wet stability is the main thing separating it from ordinary viscose.

• Wet stability. CAMEO describes modal fibres as dimensionally stable and says they do not shrink or get pulled out of shape when wet.
• Strength. The University of Georgia Extension puts HWM rayon at up to 50 per cent stronger than conventional rayon overall.
• Handle and drape. CAMEO notes a soft, silky feel. The University of Georgia lists good drape, a subdued lustre and resistance to creasing.
• Moisture. HWM rayon absorbs less moisture than conventional rayon, according to the University of Georgia, and it is still susceptible to mildew.
• Heat and light. It scorches rather than melts, and it resists sunlight better than conventional rayon.

By contrast, Cornell Cooperative Extension says regular viscose rayon has very low strength when wet, can shrink as much as 10 per cent in ordinary laundering, and is best dry cleaned.

Modal vs viscose vs lyocell

Acetate also starts from wood cellulose but belongs to a different family. EU law defines it as cellulose acetate, in which at least 74 per cent and less than 92 per cent of the hydroxyl groups are acetylated, so it is a chemically modified fibre rather than regenerated cellulose.

How is modal graded or measured?

Modal has no consumer grading scale; it is defined by a laboratory strength test and described by fibre fineness and tenacity.

Under the EU textile regulation, a fibre may be called modal only if two forces reach minimums calculated from its mean linear density in decitex: its breaking force in the conditioned state, and the force needed to stretch it by 5 per cent when wet.

CAMEO gives modal a tenacity of 3–5 g/denier, an elongation of 6–14 per cent dry and 8–20 per cent wet, and a density of 1.52–1.54. Lenzing describes the “Micro” fibres in its TENCEL™ range as the finest it makes under that brand.

How does modal appear on a clothing label?

Modal appears under its own name: “modal” is a listed fibre name in EU law, and the US Federal Trade Commission (FTC) permits it as an ISO fibre name on US labels.

In the EU

• Modal is entry 22 in Annex I of Regulation (EU) No 1007/2011, separate from viscose (25), lyocell (33) and cupro (21), so a label can tell them apart.
• “100 %”, “pure” or “all” may be used only when the product is made exclusively of one fibre, with up to 2 per cent of extraneous fibre allowed (5 per cent for carded products) if it is technically unavoidable and not added as a matter of routine.
• A trade mark may sit immediately before or after the fibre name, but it does not replace it.

In the US

• The FTC lists modal among the ISO names permitted on labels although not named in its Textile Rules.
• Fibres are listed by weight in descending order (as in the EU). A fibre under 5 per cent must be labelled “other fiber” rather than named, unless it has a clear function, such as spandex added for stretch. Wool and recycled wool are the exception: their percentage must always be stated, even below 5 per cent.
• The FTC allows a 3 per cent tolerance on blend percentages, but none when a label states a single fibre. “All” may replace “100%”.
• Labels must also show the country of origin and the company name or Registered Identification Number (RN).
• A fibre trade mark must appear next to the generic name, in the same size and with equal prominence.

Because fibres are listed in descending order of weight, modal listed after cotton or polyester makes up no more of the garment than that fibre does.

How do you tell good modal from poor modal?

You judge modal by its label and by how the garment behaves after washing, because the fibre’s defining quality is that it keeps its shape when wet.

1. Read the fibre name. In the EU, modal and viscose are separate legal names. A garment sold as “modal” in its product title but labelled viscose is regular viscose rayon, with its lower wet strength.
2. Find the generic name beside any trade mark. US and EU rules both put the fibre name next to a trade mark. A label carrying only a brand name, with no fibre name, is a red flag.
3. Check the blend. CAMEO notes modal is often blended with cotton, wool or synthetic fibres. In a stretch jersey, a small share of spandex may be named even below 5 per cent in the US because it has a function.
4. Measure after the first wash. Lay the garment flat and measure its length before and after washing as the label directs. CAMEO describes modal fibre as dimensionally stable, so noticeable shrinkage deserves a second look, although knit construction and finishing also affect it.
5. Look at hems and necklines. Cornell notes regular rayon may stretch out of shape if pulled while wet. Necklines and hems that grow or ripple after washing suggest weak wet strength.

How do you care for modal?

Follow the permanent care label first; Cornell Cooperative Extension says HWM rayon can be machine laundered and performs much like cotton.

• Bleach. Avoid chlorine bleach unless the label says it is safe (University of Georgia Extension).
• Ironing. Use a lower iron temperature than for conventional rayon; modal scorches rather than melts.
• Drying. Do not leave it damp: HWM rayon is susceptible to mildew.

Is modal sustainable?

Modal is made from wood, a renewable raw material, but its footprint depends on where the wood comes from and how the producer handles chemicals, energy and water. The figures below come from Lenzing and from Textile Exchange’s profile of Lenzing.

• Wood. Lenzing says the wood for all its TENCEL™ Modal fibres comes from certified or controlled sources.
• Process. According to Textile Exchange, Lenzing has used an integrated pulp-to-fibre process since 1977 that is self-sufficient in energy and recovers co-products from the wood.
• Emissions and water. Lenzing states that TENCEL™ Modal has at least 50 per cent lower carbon emissions and water consumption than generic modal, based on life-cycle assessment to ISO 14040/44. That is a company claim.
• End of life. Lenzing says its LENZING™ Modal standard fibres are certified by TÜV AUSTRIA as biodegradable in soil, freshwater and marine environments under the certificates’ conditions. That applies to the fibre; a garment blended with polyester or spandex is a different matter.

For how fibre choice fits the wider picture, see sustainable fashion.