Cotton
A cellulose fibre, tolerant of hot water and alkaline detergents — and measurably degraded by chlorine bleach, which cuts the cellulose chains themselves.
What not to do
Sodium hypochlorite (chlorine bleach) may damage Cotton
Best avoided
The available guidance advises against this.
Cumulative and invisible: the fabric looks fine and fails later, because the damage is to the cellulose chains rather than the appearance.
Precautions
- Limit the contact time
- Check the manufacturer's instructions
Why we say this
Strongly supported
Measured experimentally in peer-reviewed work, which is why this sits at the top of the ladder while most of the catalogue does not. Recorded as avoid rather than unsafe because the study is of industrial laundering and CleaningHQ will not convert its figures into a domestic threshold — the direction and scale carry across, the numbers do not.
Sources
Scientific Reports (Nature Portfolio), 2023 · Scientific literature
Relied on for: That ten chlorine-based wash cycles reduced cotton cellulose limiting viscosity number by more than eighty per cent against about half after one hundred ordinary commercial cycles, with tensile strength falling correspondingly. (states this directly)
Verification: a person has read the passage relied on.
Read on — Abstract; the tensile strength and limiting viscosity number results; and the conclusions. Supports a narrower statement — our claim was reduced. This is the first scientific-literature source in the register and it settled a field CleaningHQ had recorded as conflicting: cotton's bleach sensitivity is now known, because cumulative cellulose damage from chlorine is measured rather than asserted. The narrowing is that the study is of INDUSTRIAL laundering — higher concentrations and frequencies than a domestic wash — so CleaningHQ cites it for the direction and relative size of the effect and explicitly not for any domestic threshold. It also supplies the polyester-blend durability comparison used in the fabrics vertical.
Last reviewed by a person on .
In detail
Cotton is almost pure cellulose, and cellulose tolerates conditions that destroy protein fibres: hot water, alkaline detergent, protease enzymes and mechanical agitation. That tolerance makes cotton the fibre most laundry advice is implicitly written for, and it is why advice that works perfectly on a cotton shirt can ruin a wool jumper. What cotton does not tolerate is chlorine, and the size of the difference is easy to underestimate because the damage is invisible until the garment fails. A peer-reviewed laundering study measured cellulose degradation directly and found that ten chlorine-based wash cycles reduced the cellulose limiting viscosity number by more than eighty per cent, against roughly half after one hundred ordinary commercial cycles — with tensile strength following. That study was of industrial laundering rather than a domestic wash, so the figures are not a household threshold; the direction and the scale of the effect are what carry across. Dyes, finishes and blends often impose tighter limits than the cotton itself does, which is why the care label rather than the fibre is the governing instruction on a made-up garment.
Properties
Sensitivity
- Alkalis
- Not known
- Chlorine bleach
- Recorded
- Heat
- Not known
- Porous
- Recorded
“Not known” means CleaningHQ has not established this, not that the material is unaffected.
What works
Sodium percarbonate (oxygen bleach) requires the precaution Cotton
Safe only in specific conditions
This is only appropriate within specific limits. Outside those limits, CleaningHQ makes no claim.
Sprint 28. Recorded against cotton because coloured cotton is where the colour-change risk is stated.
Only within these limits:
- Permitted only where the care label's bleaching triangle allows it — empty for any bleach, two oblique lines for oxygen only
- A crossed triangle excludes oxygen bleach too, and therefore excludes universal detergents containing it
- Stated consequence is colour change rather than fibre damage
The triangle is usually read as a question about bleach. The originating body applies it to detergent: 'do not use a universal detergent which contains oxygen for bleaching purposes, unless the bleaching symbol allows its use'.
Precautions
- Check the manufacturer's instructions
- Test on an inconspicuous area first
Why we say this
Supported
The originating body of the care-labelling system, stating the link between its own bleaching symbol and everyday detergent choice. Recorded at the strength it is given: a colour-change risk with a stated exception, not a damage prohibition.
Sources
GINETEX, The International Association for Textile Care Labelling · Standards body
Relied on for: That a universal detergent containing oxygen for bleaching purposes should not be used on coloured textiles unless the bleaching symbol allows it, with a stated risk of colour change, and that oxygen / non-chlorine bleach is contained in most universal detergents. (states this directly)
Verification: a person has read the passage relied on.
Read on — Sprint 28 read all thirty pages: the fold-out table on pages 1-2, then Basic Principles, Washing, Bleaching, Drying, Ironing, Professional Textile Care and Labelling on pages 6-24. Earlier sprints had read the fold-out table only. Supports a wider statement — our claim was widened. The register held this as a one-page symbol table for four sprints. It is a thirty-page booklet, and the pages nobody had opened carry the principles rather than the pictures: a label is set by the garment's most sensitive COMPONENT, not its fibre; following it guarantees no damage and guarantees nothing about stain removal; milder is always permitted; and the bleaching triangle governs ordinary detergent choice, because universal detergents contain oxygen bleach. Two whole treatment families — natural drying and professional textile care — become science concepts on it.
Last reviewed by a person on .
Why
- Cotton is explained by Adsorption of odour molecules
Sprint 27. Why the fibre that holds odour is the one that smells less.
- Cotton is explained by Fibre swelling and shrinkage
- Cotton is explained by Oxidation and bleaching
Quantified rather than asserted. Ten chlorine washes did more damage to the cellulose than one hundred ordinary ones.
Related
- Cotton is commonly affected by Perspiration
- Cotton is commonly affected by Sunscreen
- Cotton is commonly affected by Antiperspirant residue
Hacks and claims involving this
- Hotter washes clean better Disputed
- Hot water for a blood stain Does not work
- A stronger solution cleans better Does not work
- Freezing chewing gum off with ice Unresolved
- Washing silk at home Disputed
- Lifting candle wax with a warm iron and paper Unresolved
- Drying wool flat rather than hanging it Supported
- The care label allows oxygen bleach even when it bans chlorine Does not work
- The dots on a care label are just a rough guide Does not work
- Fabric softener is fine on everything Does not work
- Washing cold prevents shrinking Disputed
- A stain method that works on cotton works on anything Does not work
- Orange sunscreen marks are rust Does not work
Sources for this page
Sources
Scientific Reports (Nature Portfolio), 2023 · Scientific literature
Relied on for: That chlorine-based laundering degrades cotton cellulose far faster than ordinary washing, measured as limiting viscosity number and tensile strength loss, and that cotton-polyester blends retain strength better than pure cotton. (states this directly)
Verification: a person has read the passage relied on.
Read on — Abstract; the tensile strength and limiting viscosity number results; and the conclusions. Supports a narrower statement — our claim was reduced. This is the first scientific-literature source in the register and it settled a field CleaningHQ had recorded as conflicting: cotton's bleach sensitivity is now known, because cumulative cellulose damage from chlorine is measured rather than asserted. The narrowing is that the study is of INDUSTRIAL laundering — higher concentrations and frequencies than a domestic wash — so CleaningHQ cites it for the direction and relative size of the effect and explicitly not for any domestic threshold. It also supplies the polyester-blend durability comparison used in the fabrics vertical.
What CleaningHQ cannot answer yet
These are recorded questions about this subject that we have not yet researched to a standard we would publish.
- Remove oily soil from textiles
- Remove protein staining from fabric
- Remove tannin staining from fabric
- Remove protein and residue staining from collars and underarms
- Remove chlorophyll and pigment staining from fabric
- Compare drying methods for fabric longevity
- Laundering frequency for towels
- Laundering frequency for bed linen
- Explain stiffening of cotton towelling
- Tumble drying suitability for cotton
- Remove set oily staining from textiles
- Remove particulate soil from cotton
- Remove pigmented oily soil from cotton
- Remove aluminium salt and oil residues from fabric
- Remove turmeric pigment staining from fabric
- Remove solidified wax from textiles
- Remove adhesive polymer from fabric
Last reviewed by a person on .