# Antifungal socks

The microclimate of the shod foot and the physiology of Trichophyton, wool's hygroscopicity and odour-acid binding, why regenerated cellulose inherits no bamboo chemistry, and how biocidal finishes are tested for durability.

A fibre almost never kills fungus — it manages moisture; anything that does kill has been added, and has to survive the wash.

Source: https://en.bioecon.ru/docs/forestry-biomaterials/fibers-textiles/bio-socks-antifungal/
Updated: 2026-09-04



Athlete's foot is caused by dermatophytes — principally *Trichophyton rubrum* — which feed on the keratin of the stratum corneum. Their growth is governed less by the presence of spores, which are close to ubiquitous, than by local conditions: water activity at the skin surface, a temperature near 30 °C, and maceration of the epidermis between the toes. A shoe creates a closed volume, the foot sweats substantially through a day, and the textile in between decides whether that surface stays wet. This leaves a sock exactly one defensible mechanism: it alters the microclimate.

## What wool actually does

Merino fibre is hygroscopic. Keratin binds water vapour within its amorphous regions, and the fibre can take up on the order of a third of its own mass while still feeling dry. Sorption releases heat, which damps temperature swings. More important, water held in the amorphous phase does not form the free surface film at the skin that a dermatophyte needs.

Odour is a separate question. Sweat itself is nearly odourless; the volatile short-chain carboxylic acids and thiols come from skin bacteria metabolising sweat and sebum components. Wool retains those acids within the fibre and releases them slowly, so the sock stays subjectively fresher for longer. That is sorption, not killing, and conflating the two is not honest. Lanolin, meanwhile, is almost entirely removed when wool is scoured before spinning, so it cannot explain anything about the finished garment.

## Why bamboo viscose inherits nothing

Here the line between claim and mechanism is sharp. Bamboo reaches textile form by the viscose route: alkali treatment, xanthation with carbon disulfide, dissolution, then regeneration of cellulose through a spinneret. Only the cellulose chain survives that passage; lignin, extractives and any putative antimicrobial metabolites stay in the process waste. The resulting fibre is chemically indistinguishable from wood-pulp viscose. Regulators including the US Federal Trade Commission have accordingly acted against sellers making natural-antibacterial bamboo claims for viscose fabrics. Mechanically processed bamboo bast fibre is a genuinely different material, but it is scarce and coarse.

## When a finish is real

An added biocide — silver, zinc compounds, quaternary ammonium silanes — works by a comprehensible mechanism: membrane disruption and binding to enzyme thiol groups. The difficulty is not efficacy but fixation. An unbound agent washes out, losing its function and entering the effluent. Finishes are therefore assessed after repeated laundering rather than once: antibacterial activity by AATCC 100 or ISO 20743, antifungal by AATCC 30. In the EU such goods fall under the Biocidal Products Regulation 528/2012 as treated articles: the active substance must be approved for the relevant product type, and a claim of protection for the article itself must be declared on the label.

The honest consumer statement is that keeping the foot dry and changing socks prevents more than any finish does, and that an established infection is treated with an antifungal drug, not with a textile.