Microfiber
Also searched as: microfibre, micro-denier, microdenier, microfilament, ultrafine fiber
A manufactured fiber or filament finer than a conventional threshold, often set at 1 decitex (0.1 tex) per filament, used for soft, dense fabrics and cleaning cloths.
In detail
Microfiber is a size category, not a polymer. Polyester, nylon and other polymers can be made as microfibers by spinning very fine filaments directly, or by spinning bicomponent filaments that are later split apart or have one component dissolved away. Finer filaments bend more easily, so a yarn with many fine filaments is softer and drapes better than one with fewer coarse filaments of the same total linear density. The much larger surface area per gram gives microfiber fabrics strong wicking and particle capture, and their dense packing makes them wind resistant while still passing water vapor.
The science and numbers
A review of melt-spun fibers gives standard multifilaments as about 10 to 40 micrometers per filament, which for PET corresponds to roughly 0.1 to 1.7 tex, and defines a microfiber as below 0.1 tex. The unit arithmetic: 1 denier is 1 gram per 9,000 m and 1 decitex is 1 gram per 10,000 m, so 1 denier equals about 1.11 dtex. For a round filament, diameter in micrometers is about 11.28 x sqrt(dtex / density in g/cm3); a 1 dtex PET filament (density about 1.38) is roughly 9.6 micrometers across. Ultrafine fibers below 1 micrometer come from bicomponent routes: segmented-pie filaments of two poorly adhering polymers split under mechanical stress, while islands-in-the-sea filaments have their matrix dissolved to release the embedded fibrils.
A practical example
A class compares two polyester yarns of the same total linear density, one made of 36 filaments and one of 144. The 144-filament yarn has much finer filaments, so it feels softer and packs into a denser woven cloth. Calculating surface area per gram for both shows why the finer yarn picks up more oil when wiped across a greasy surface.
What to distinguish
Microfiber describes filament fineness, not fiber type, recycled content or environmental performance. In environmental science the same word is used for fiber pieces shed during washing, a separate topic covered under fiber fragment release. Thresholds are not harmonized across sources and units; a limit written as 1 denier is about 11% coarser than 1 dtex. Ask for the polymer and the linear density per filament.
Origins and history
The word joins micro with fiber and first named deliberately engineered ultrafine synthetic filaments. Producing them at scale depended on bicomponent melt spinning, which the review cited here dates to the 1960s, and on splitting or dissolving steps that free fine filaments from a composite fiber. Later, environmental researchers adopted microfiber for fibers shed from clothing in washing-machine effluent, which is why the word now carries two quite different meanings.
Related terms
Sources & further reading
- Materials: Melt-spun fibers for textile applications (Hufenus et al., 2020)
- ISO: ISO 1144:2016 Universal system for designating linear density (Tex System)
- Marine Pollution Bulletin: Capturing microfibers, marketed technologies reduce microfiber emissions from washing machines (McIlwraith et al., 2018)
Technical references reviewed 2026-09-22. Examples are illustrative. Industry organizations and manufacturers describe their own fields; their references are not independent product endorsements. Figures are approximate and depend on the stated test conditions.