A cellulase enzyme wash cuts off the loose fibre ends that become fuzz and pills, so cotton and viscose feel smoother and pill less. It does nothing to polyester in a blend. Strength is the cost: in one cotton study, bursting strength fell by up to 24.7% while weight loss stayed under 1.5%.
This post uses women’s dresses, tops, kaftans and resort wear as the examples. It covers what the wash removes, why the hand changes, what happens to pilling, what the wash costs in strength, and what to put in the spec.
What does an enzyme wash actually take off a cotton or viscose surface?
It takes off the fibre ends and microfibrils that stick out of the yarn, plus a thin layer of the most accessible cellulose. Nothing else on the garment is the target.
Cellulase is a group of enzymes that break the bonds between glucose units in a cellulose chain. They can only act where they can reach. The parts they reach first are the fibre surface and the less ordered regions between crystallites. A loose fibre end sticking out of the yarn is almost all surface, so it is weakened first.
Buschle-Diller and co-workers treated cotton, linen, ramie and viscose rayon with cellulase. Removing the surface fibrils came first, and the loss of that fibrillar matter was the main cause of early weight loss. X-ray crystallinity did not change, which the authors read as the enzyme attacking accessible chain ends on crystallite surfaces (Textile Research Journal, 1994).
The enzyme weakens the fibre ends. Tumbling breaks them off. A Novo Nordisk patent on defuzzing and depilling says the effect does not appear without the mechanical step that follows the enzyme (US 6,051,414). In a garment wash, the drum supplies that action.
Acid and neutral cellulases
Commercial cellulases come in two main families. Acid cellulases are based on Trichoderma and work best at pH 4.5 to 5.5 and 45 to 55 °C. Neutral cellulases from Humicola work best at pH 6.0 to 7.0 and 40 to 55 °C (Uddin, Textiles and Clothing Sustainability, 2015).
They do not behave the same. In Uddin’s trials on cotton jersey, the acid enzyme gave better abrasion resistance. The neutral enzyme gave less strength loss at every dose (table below). Literature reviewed in a 2023 denim study reports that acid cellulases cause more dye redeposition, or backstaining, than neutral ones (Ben Marzoug and Cheriaa, Journal of Textile Science and Technology, 2023). That matters most where loose dye is in the bath, as with indigo.
Why viscose and lyocell are different from cotton
Viscose and lyocell are regenerated cellulose. The enzyme sees the same chemistry but a different structure.
Native cotton is around 70% crystalline. Viscose is about 25 to 30%, and its crystallites are much smaller. Its chains are shorter too: a degree of polymerisation of 250 to 400 for viscose, 400 to 700 for lyocell and about 2,000 for cotton (Peterson et al., Sustainability, 2022). More of a viscose fibre is open to the enzyme, and each chain starts shorter.
Lyocell has its own problem. It fibrillates when it is abraded wet. A Courtaulds patent describes long fibrils peeling away to give a hairy surface and a frosted look on dyed fabric. It calls this primary fibrillation. Short fibrils that stay inside the fabric give a peach-skin finish, which it calls secondary fibrillation. Cellulase can remove fibrils from fibrillated lyocell fabric (US 5,759,210). On lyocell, then, the wash is a fibril-control step as well as a cleaning step.
For the fibre background, see rayon vs viscose for summer garments.
Why does it feel softer and less fuzzy?
It feels softer because the stiff, scratchy fibre ends are gone and the fabric bends more easily. It looks less fuzzy because those same ends no longer stand off the surface. Heavy pressing changes the surface too, but by flattening it into a shine rather than removing fibre; see why pressing browns or polishes cotton, linen and viscose.
Stiffness can be measured as bending length. A shorter bending length means a more pliable fabric. In Uddin’s study, bending length fell by up to 31.62% with the acid enzyme and up to 44.26% with the neutral enzyme, against the untreated fabric (Uddin, 2015).
The Novo Nordisk patent says a weight loss of 3 to 5% will usually give proper softness while keeping strength loss acceptable (US 6,051,414).
Fibre type changes the result. In a study of acid cellulase on cotton and viscose rayon, the treated rayon fabrics were more flexible than the treated cotton ones (Lee, Textile Science and Engineering, 2003). For a viscose kaftan or a cotton voile top, the same wash will not give the same hand.
The surface also looks cleaner. Uddin reports that with the hairy fibres removed, the fabric surface became cleaner and abrasion resistance improved.
Does it stop pilling, and what doesn’t it stop?
It reduces pilling on cotton and viscose by removing the loose fibres that pills form from. It does not stop pilling from fibres the enzyme cannot digest.
In Uddin’s study, the untreated cotton jersey rated 3 on a 1-to-5 pilling scale after 2,000 rubbing cycles (5 means no pilling). After acid cellulase treatment, most samples rated 4 to 5 or 5. The same paper cites earlier work that a weight loss of about 1 to 2% can be enough to give a marked drop in pilling on knitted fabric (Uddin, 2015).
What it does not do:
- It does not touch polyester. Cellulase acts on cellulose only. A Novozymes team used a different enzyme, a cutinase, to bio-polish polyester, and paired it with a cellulase for polyester/cotton (McCloskey and Jump, Textile Research Journal, 2005). In a cotton/polyester dress, the polyester fibres are left as they were.
- It removes the fuzz that is there at the time of the wash. Ask for a pilling test on the washed fabric, not a promise.
- It does not change fibre, yarn or fabric build. Those decide most pilling behaviour. We cover them in why scarves pill and how to specify one that doesn’t.
How much strength does it cost, and when is it too much?
It costs more strength than weight. In the cotton study above, a weight loss below 1.5% came with a strength loss of up to 24.7%. It is too much when the washed fabric fails the strength floor you set before bulk.
Uddin treated cotton single jersey with an acid cellulase (Mega PK) and a neutral cellulase (Mega L) at three doses, three temperatures and three times. Strength was measured as bursting strength (Uddin, 2015).
| Enzyme dose | Weight loss, acid enzyme | Bursting strength loss, acid enzyme | Bursting strength loss, neutral enzyme |
|---|---|---|---|
| 0.5% | 0.25 to 0.39% | 1.7 to 7.4% | 1.5 to 5.9% |
| 1% | 0.62 to 0.89% | 8.2 to 15.6% | 6.6 to 12.4% |
| 1.5% | 0.98 to 1.42% | 16.5 to 24.7% | 12.5 to 18.9% |
Source: Uddin, Textiles and Clothing Sustainability, 2015. Cotton single jersey. Weight loss with the neutral enzyme ranged from 0.20 to 1.22% across all trials.
Two points stand out. Strength loss climbs much faster than weight loss. And at the same dose the neutral enzyme cost less strength than the acid one.
In a 2023 study of four denim fabrics treated with neutral cellulases, the largest losses were 20.2% (warp) and 15.4% (weft) in tear strength, and 28.1% (warp) and 17.2% (weft) in tensile strength (Ben Marzoug and Cheriaa, 2023).
Where the limits sit
Uddin cites two benchmarks from earlier literature. Weight loss should not exceed 3 to 5%. A strength loss of 10% is considered commercially acceptable for bio-polishing. Read against the table, the 1% acid dose already crossed that 10% line at some settings, at a weight loss below 1%.
Viscose needs a tighter watch. After 48 hours of treatment, Buschle-Diller and co-workers found strength retention ran viscose rayon far below cotton, then ramie, then linen. Viscose yarn strength fell steadily as weight loss rose (Textile Research Journal, 1994). The studies do not agree on weight loss. Buschle-Diller found rayon lost the most weight. Lee found cotton lost more than rayon under that study’s conditions (Lee, 2003). So a weight-loss figure set for cotton cannot be carried over to viscose. Set limits for each fabric.
Weight loss is the control metric
Weight loss is how the wash is controlled. It is measured as the drop in fabric weight from before to after treatment, as a percentage. The Novo Nordisk patent gives a general range of 0.5 to 10%, with 3 to 5% as the most preferred (US 6,051,414). A later Novo Nordisk patent aims for a pilling benefit at less than 2% weight loss, and describes 3 to 5% as typical of conventional bio-polishing (US 5,916,798).
Weight loss is a control, not a guarantee. The table shows strength can fall past a commercial limit while weight loss still looks small. Measure both.
How the enzyme is stopped
The enzyme keeps working until it is deactivated. It is stopped by raising the temperature or the pH for a set time. The level needed depends on how heat-stable or pH-tolerant that enzyme is. Some bleaching agents also deactivate it (US 6,051,414). The patent’s examples stopped the reaction with dilute sodium hydroxide at pH 10. Uddin ended treatment by holding the bath at 85 °C for 10 minutes.
Skipping this step costs strength. In the denim study, the inactivation step had a significant effect on tensile strength loss, and the authors conclude it should be applied to avoid fabric damage (Ben Marzoug and Cheriaa, 2023).
What should the spec say?
The spec should name the enzyme type, cap the weight loss, set a strength floor and a pilling grade, and require a recorded deactivation step. Test all of it on the bulk fabric.
- Fabric and fibre. Full composition. For a blend, accept that the polyester or nylon part will not be polished.
- Earlier treatment. Say whether the fabric was already bio-polished at the mill. A second cellulase step takes off more cellulose.
- Enzyme type. Acid or neutral cellulase, or ask the processor to state which one they use.
- Weight-loss maximum. Measured on fabric swatches run in the same load as the garments. The sources above put the ceiling at 3 to 5%; on knits, 1 to 2% has been reported enough for a marked pilling gain.
- Strength floor. For woven dresses, tops and kaftans: tear and tensile strength, warp and weft, before and after the wash. For jersey: bursting strength. State the maximum loss as a percentage, or a minimum value after washing. Set a tighter figure for viscose than for cotton.
- Pilling grade. The grade required after a stated number of rubbing cycles, with the test method named.
- Hand standard. A washed swatch signed off as the softness reference.
- Deactivation. Temperature and time, or pH and time, written on the wash record.
- Lyocell. Say whether the target is a clean surface or a peach-skin finish.
Approve the wash on bulk fabric, not the sample yardage. The top-of-production sample is the right place to check hand, fuzz and strength together. Put the wash line in the tech pack so it travels with the order.
KK Fashion Exports has made dresses, tops, kaftans and resort wear for buyers worldwide since 2003. Garments start from 200 pieces per style, per colour. Send the spec with the wash line filled in and we will quote against it.
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