There is a gap between what clothing is made of and what it arrives as. A garment described as 100% cotton reaches you as the product of a series of chemical treatments applied after the fabric was woven — treatments that affect how it looks, feels, resists wrinkles, stays white, repels stains, or holds a crease. The cotton fibre itself may be entirely benign for sensitive skin. The finishing chemistry layered on top of it frequently is not.
What fabric finishing is, and why it happens
Fabric finishing is the collective term for everything done to a woven or knitted fabric after construction and before a garment reaches the consumer. The raw fabric emerging from a loom is rarely commercially useful — it needs to be bleached, dyed, softened, or treated to meet the expectations of a market that expects white cotton to stay white, shirts to resist creasing, and performance fabrics to repel water. These results come from chemistry, and most of that chemistry stays in or on the fabric.
The processes are varied and the chemicals involved are numerous. Some are applied in dilute concentrations and largely wash out. Others form chemical bonds with the fibre structure and remain present through many wash cycles. From the outside, there is no reliable way to tell which category any given garment falls into. The label says cotton. The chemistry present is rarely disclosed anywhere.
Wrinkle resistance and the formaldehyde problem
Easy-care finishes — sold as wrinkle-resistant, non-iron, or crease-resistant — are among the most widely applied textile treatments and among the most consistently problematic for sensitive skin. The standard chemistry used to achieve these results involves compounds that cross-link cellulose fibres in cotton, holding their shape against deformation. The most established of these are formaldehyde-releasing agents, which do exactly what the name suggests: they break down under warmth and humidity to release formaldehyde.
Formaldehyde is a well-documented skin sensitiser and irritant. It is classified as a contact allergen, meaning that repeated skin exposure can trigger an immune response that then produces reactions on subsequent contact. Wrinkle-resistant shirts, bedding, and non-iron cotton items are the most common sources in everyday clothing. The release occurs in the conditions that clothing regularly experiences: body warmth, perspiration, and moisture. For people who have not previously reacted to these garments, the exposure can sensitise the skin over time. For people already reactive to formaldehyde, a new easy-care garment can produce a reaction within hours.
Regulations in different markets set different maximum limits for residual formaldehyde in textile products. These limits vary considerably and apply to the fabric as sold, not after repeated washing. A garment may pass regulatory tests and still contain levels that are meaningful for a person with sensitive or already-compromised skin. The practical response for sensitive skin is to wash wrinkle-resistant and non-iron garments several times before wearing, which reduces but does not eliminate residual formaldehyde — and to consider whether easy-care finishes are worth the trade-off.
Optical brighteners and UV reactivity
White fabrics and many pale-coloured ones are treated with optical brightening agents — fluorescent compounds that absorb ultraviolet light and re-emit it as visible blue-white light, making the fabric appear brighter and whiter than untreated material. These compounds are present in most commercially white cotton clothing, in bed linen, and in many laundry detergents intended to maintain whiteness.
Optical brighteners remain in fabric after washing — that is the point of them. For sensitive skin, particularly skin that is already reactive or has a compromised barrier, the ongoing presence of fluorescent compounds against the skin is a variable that is easy to overlook precisely because white fabric seems like the neutral, benign choice. Reactions to optical brighteners are less common than reactions to formaldehyde, but they are documented and are most relevant in people whose skin is reactive to sunlight, whose symptoms are concentrated in sun-exposed areas, or who have noticed that reactions seem correlated with new white clothing or changes in laundry detergent.
Softeners applied during manufacturing — not the same as what you add at home
Much of the softness of new clothing comes not from the fibre itself but from silicone-based or polymer softeners applied industrially during finishing. These feel pleasant initially and are a significant part of why new garments feel noticeably better in a shop or out of packaging than they do after several washes. As they wash out, the underlying character of the fabric — rougher or softer depending on fibre quality and construction — becomes apparent.
Industrial softeners are not the same chemistry as domestic fabric conditioner, though some of the concerns overlap. For sensitive skin, the relevant issue is that these coatings sit at the interface between fabric and skin throughout the wearing of a new garment, before they have had the opportunity to wash out. People who find that new clothing irritates more than established clothing, or that symptoms ease after the first few washes, are often experiencing the washing-out of these finishing layers rather than the fabric itself changing.
This is one reason why washing new clothing before wearing it is consistently useful for sensitive skin — not primarily for bacterial contamination, which is commonly cited, but to remove the top layer of manufacturing chemistry before it has extended contact with skin.
Antimicrobial treatments and the silver question
Performance clothing, activewear, and increasingly some everyday garments are treated with antimicrobial agents intended to reduce odour by inhibiting bacterial growth in the fabric. The most common are silver-based compounds, which disrupt bacterial cell membranes, and various biocidal chemicals applied as finishes. These treatments are generally effective for their intended purpose — reducing odour retention in synthetic performance fabric — and they are widely marketed as a feature.
For sensitive skin, the relevant consideration is that antimicrobial treatments are designed to be biologically active. They kill bacteria because they are chemically aggressive enough to do so. The concentrations used are calibrated against bacterial tolerance, not skin sensitivity, and skin is not a uniform substrate — compromised skin, skin with a disrupted barrier, and skin already in a reactive state responds differently to the same chemical exposure than intact, healthy skin. Silver-based antimicrobials are among the more studied and relatively better tolerated of these treatments, but other biocidal finishes are less well characterised in terms of skin response. For sensitive skin, the presence of an antimicrobial treatment is a variable worth noting, particularly if reactions are concentrated in areas covered by treated garments or are worse with activewear.
Reading labels and knowing what they cannot tell you
Clothing labels in most markets are required to disclose fibre composition and, for some product categories, the presence of certain restricted substances. They are not required to disclose finishing chemistry, and most do not. A label that says 100% organic cotton can accompany a fabric that has been treated with any combination of the finishes described here — finishing processes are applied after the fibre is grown and woven, and organic certification typically covers the fibre, not what happens to it in the factory.
The practical tools available to consumers are indirect: washing before wearing, preferring producers who use GOTS (Global Organic Textile Standard) certification that covers processing as well as fibre, and paying attention to whether reactions follow the pattern of new-garment exposure and ease with washing. For skin that is consistently more reactive to new clothes than established ones, or that shows clear patterns with specific garment types, finish chemistry is often a more productive line of investigation than fibre alone.
Understanding that a garment has layers — the visible, the structural, and the chemical — makes it possible to approach textile choices with more precision than a fibre label can support on its own.