Naturally coloured cotton develops pigment while its fibres grow on the plant. Its brown or green appearance can therefore come from the fibre itself, without adding a textile dye to create that colour. For a buyer, the useful first question is where the colour originates; the next questions concern composition, processing and the performance of the actual yarn or fabric.
Brown cotton: evidence from proteins, genes and pigment chemistry
The supplied studies approach brown pigmentation at several levels. Li and colleagues compared developing brown fibres with a closely related white line and identified differences in proteins associated with pigment metabolism and fibre development [R01]. This provides biological evidence about the growing fibre; it does not measure a finished fabric.
Feng and colleagues then measured four flavonoid compounds and the activity of associated genes at different stages of fibre development. Both the compounds and the corresponding gene expression were higher in the brown material studied than in the white comparison material [R02]. Flavonoids are a family of plant compounds; these findings connect brown fibre colour to the plant’s own metabolism.
A 2014 investigation examined proanthocyanidins, a group of plant polyphenols. It found differences in their composition between brown and white fibres and proposed that quinones formed through oxidation contribute directly to brown colour [R04]. The practical conclusion is more precise than “brown cotton contains natural dye”: the plant builds and modifies compounds as its fibre develops.
Green cotton follows a different research trail
Green pigmentation should not be explained by simply copying the brown-cotton mechanism. An early protein survey mapped proteins in developing green fibre [R03]. Later work identified caffeoyl derivatives and examined an enzyme involved in their formation [R05]. Another study found higher lignan content and associated protein and gene activity in the green material studied; its staining results distinguished the green pigment from brown-fibre proanthocyanidins [R06].
These are complementary clues, rather than proof that one molecule explains every green variety. The 2021 research perspective brings together evidence for different brown and green pathways and discusses the remaining breeding challenges [R07]. It is a perspective on the field, not a new performance test of a commercial yarn.
Three distinctions that matter in a purchase specification
Natural colour describes the origin of the pigment. It does not state the percentage of coloured cotton in a yarn.
Organic certification concerns the named product, holder, standard and certification scope. Natural pigmentation alone does not establish organic status.
A dye-free production declaration describes a process. It does not by itself establish washing fastness, light fastness, skin compatibility or a percentage reduction in environmental impact.
How to turn the research into a useful sample request
Ask for the coloured-fibre percentage, the other fibres in the blend, yarn count and whether the yarn is single or plied. Agree a physical shade reference and the processing route before comparing swatches. If colour after washing or exposure to light is important, request tests on the actual construction and finish you intend to buy.
For example, OrganicTex’s currently confirmed brown single-yarn offer is Ne 32, Ne 40 and Ne 50, each with 35% naturally brown cotton and 65% white cotton. The confirmed route uses no dyeing, bleaching or fluorescent whitening agent. These are supplier specifications, separate from the research findings above; the papers did not test these products.
Compare yarn specifications and request a sample
Research references
Prepared by OrganicTex Group with AI assistance and checked against the cited papers and confirmed supplier information. This is a supplier-authored reading guide, not original experimental research. The cited authors and institutions do not endorse OrganicTex products.