How to Wash Micromodal
Micromodal is modal fibre spun below 1 dtex — finer than standard modal, with a higher draw-ratio crystallinity and better wet tensile strength. Unlike viscose (which loses 40–50% strength when wet), micromodal can be machine washed on a gentle cycle at 30–40°C. Use non-bio detergent: cellulase enzyme in bio detergent degrades regenerated cellulose over repeated washes.
The Chemistry
Micromodal is a variant of modal fibre — both are regenerated cellulose fibres produced by dissolving cellulose from wood pulp and extruding the dissolved cellulose through a spinneret into a coagulation bath, where the cellulose re-solidifies as a continuous filament. The chemistry of cellulose dissolution and regeneration is identical between modal and micromodal. The critical difference is the spinneret hole diameter and the draw ratio applied to the freshly extruded filament. Fibre linear density is measured in dtex — the mass in grams of 10,000 metres of fibre. A lower dtex number means a finer (thinner) filament. Standard modal fibre is typically 1.3–1.8 dtex per filament. Micromodal fibre is spun at sub-1 dtex per filament — Lenzing MicroModal, the primary commercial product, typically produces filaments at approximately 0.9 dtex. This difference seems small but has significant structural consequences. Producing a finer filament requires extruding the cellulose solution through a smaller spinneret hole and then drawing (stretching) the freshly extruded filament at a higher draw ratio before it fully solidifies. The drawing step aligns the cellulose polymer chains along the fibre axis — the higher the draw ratio, the more aligned (crystalline) the polymer chains become. Higher crystallinity produces two effects: higher tensile strength (aligned chains distribute stress more evenly) and better wet tensile strength (crystalline regions are less accessible to water molecules, so the fibre swells less and maintains structural integrity better when wet). This is the wet-strength hierarchy for regenerated cellulose fibres: standard viscose loses approximately 40–50% of its dry tensile strength when wet — the amorphous, randomly oriented polymer chains in viscose absorb water readily, swell, and the fibre becomes vulnerable to mechanical damage. Modal (higher draw ratio, higher crystallinity than viscose) retains much better wet strength — manufacturers quote values 50–80% better than viscose. Micromodal (even higher draw ratio, even higher crystallinity) retains wet strength better still. This is not to say micromodal is strong when wet — it is not as strong as cotton or linen — but it is genuinely machine washable at gentle cycle settings, whereas viscose is not. The softer hand feel of micromodal relative to standard modal is a direct consequence of the finer filament. A finer filament means more individual filaments occupy the same cross-sectional area in a yarn. More filaments per yarn cross-section means a smoother, more continuous surface at the microscopic level — fewer protrusions and valleys — which translates to a softer, smoother feel against skin. This is why micromodal is preferred for underwear and intimate apparel where skin contact is constant, while standard modal is used for loungewear, T-shirts, and bedding. Lenzing MicroModal is produced exclusively from beechwood cellulose — specifically from European beech forests (predominantly Austria and Germany) that are managed under certified sustainable forestry programmes. The production uses a modified viscose process (similar chemistry to standard modal) but with the finer spinnerets and higher draw ratios described above. A care note specific to regenerated cellulose fibres including micromodal: enzyme (biological) detergents containing cellulase can over time hydrolyse cellulose chains on the fibre surface. Cellulase is included in some bio detergents to brighten cotton fabrics and remove surface fuzz — on regenerated cellulose, repeated cellulase exposure gradually degrades the surface, reduces the fibre diameter, and accelerates fibre breakage. Non-biological (enzyme-free) detergent avoids this. For occasional washing this is a minor concern; for frequent laundering of micromodal garments, non-bio detergent is better long-term care.
Step-by-step
- 1
Machine wash at 30–40°C on a gentle cycle — micromodal is genuinely machine washable
Micromodal's higher draw-ratio crystallinity gives it significantly better wet tensile strength than standard modal or viscose. It can withstand a gentle machine cycle at 30–40°C without the structural damage that washing would cause in viscose. Use the delicates or gentle cycle to limit agitation, but a short normal cycle at 30°C is also acceptable. Do not hand wash only — micromodal does not require the same extreme care as viscose or silk.
- 2
Use non-biological (enzyme-free) detergent — cellulase enzyme in bio detergent degrades cellulose over time
Biological detergents contain enzymes including cellulase, which is included to remove surface fuzz and brighten cotton fabrics. Cellulase hydrolyses cellulose polymer chains on the fibre surface. For occasional washing, this effect is negligible. For garments washed frequently (underwear, activewear), repeated cellulase exposure gradually reduces fibre surface integrity and accelerates wear. Use a non-bio or mild liquid detergent. Avoid bleach — chlorine bleach oxidises and degrades cellulose fibres.
- 3
Cold rinse and low spin — reduce mechanical stress during the extraction phase
Even with its better-than-modal wet strength, micromodal is still a regenerated cellulose fibre that is weaker when wet than when dry. The spin cycle subjects the wet fabric to centrifugal force and brief high mechanical loading. A moderate spin speed (600–800 rpm) is sufficient to extract the majority of water without excessive stress. High-speed spin (1200–1400 rpm) on very wet fabric applies significantly higher force — avoid on micromodal, particularly for delicate underwear and fine-knit garments.
- 4
Air dry flat or low tumble dry — micromodal is dimensionally stable when handled gently
Micromodal has excellent shape retention compared to viscose. It can be tumble dried on a low heat setting without significant shrinkage or distortion, though air drying flat or hanging is the safest approach for fine garments. Avoid hanging heavy micromodal items (thick knit tops) while wet — the weight of water stretches the fabric under gravity. Light garments (underwear, T-shirts) can be hung without issue. Never tumble dry on high heat — while micromodal is not as heat-sensitive as polyester, unnecessary heat accelerates fibre degradation over repeated cycles.
- 5
Iron on low heat if needed — micromodal does not need high temperatures
Micromodal is a smooth cellulose fibre that does not wrinkle as severely as linen or cotton. If ironing is needed, use a low heat setting (synthetic or silk setting, 110–130°C) with steam or a slightly damp pressing cloth. The fine filament structure is susceptible to surface sheen (glazing) from direct high-heat contact — iron on the reverse side or through a pressing cloth. Most micromodal underwear and activewear does not require ironing.
- 6
Wash colours inside out and separately on first wash — micromodal dyed with reactive dyes can bleed
Micromodal is typically dyed with reactive dyes that form covalent bonds with the cellulose hydroxyl groups — the same dye chemistry as cotton. Reactive dyes on micromodal are generally well-fixed, but dark colours (black, navy, deep red) may bleed slightly on the first wash as unfixed dye residue washes out. First wash dark micromodal items separately or with similar colours inside-out. After the first wash, colour bleeding is usually not a concern under normal wash temperatures.
Micromodal washing guide by type
| Type | Wash | Dry | Iron | Notes |
|---|---|---|---|---|
| Micromodal underwear (Lenzing MicroModal) | 30°C gentle cycle; non-bio detergent | Air dry or tumble dry low | Not usually needed; low heat if required | Non-bio detergent especially important for frequently washed items |
| Micromodal T-shirts and tops | 30–40°C gentle cycle | Air dry or low tumble dry | Low heat; reverse side or pressing cloth | Less fibrillation risk than viscose or standard modal |
| Micromodal-cotton blend | 30–40°C machine wash; any mild detergent | Tumble dry low or air dry | Low-medium cotton setting | Cotton component adds durability and reduces cellulase sensitivity |
| Micromodal activewear | Cold 30°C; sport or non-bio detergent | Air dry preferred | No iron needed | Check blend — elastane common in activewear; no heat above 40°C for elastane |
| Micromodal lounge / sleepwear | Cold–30°C gentle cycle | Air dry flat or low tumble | Low heat only | Most micromodal sleepwear is micromodal-cotton blend; check label |
| Micromodal vs standard modal (comparison) | Both: 30–40°C gentle; non-bio preferred | Both: low tumble or air dry | Both: low heat | Micromodal: finer filament, softer, better wet strength; modal: slightly coarser but similar care |
Frequently asked questions
What is the difference between micromodal and modal?
Both are regenerated cellulose fibres made from beechwood pulp. The difference is filament fineness and draw ratio during production. Standard modal is typically 1.3–1.8 dtex per filament. Micromodal is spun at sub-1 dtex per filament (Lenzing MicroModal is approximately 0.9 dtex). The finer filament is produced by extruding through a smaller spinneret hole and drawing at a higher ratio, which aligns cellulose polymer chains more — resulting in higher crystallinity, better wet tensile strength, and a softer, smoother surface feel. Micromodal is preferred for underwear and skin-contact garments; modal is used for loungewear and bedding. Care requirements are essentially identical: both are machine washable at 30–40°C on a gentle cycle.
Can micromodal be machine washed?
Yes. Micromodal is genuinely machine washable, which is a key difference from standard viscose (rayon). The higher draw-ratio crystallinity of micromodal gives it significantly better wet tensile strength than viscose, which loses 40–50% of its strength when wet. Micromodal can withstand a gentle cycle at 30–40°C. Use the delicates or gentle cycle setting to limit agitation, and a moderate spin speed (600–800 rpm rather than 1200+ rpm) to reduce mechanical stress on the wet fibre. Non-biological detergent is preferred for frequently washed items.
Does micromodal shrink?
Micromodal has good dimensional stability compared to viscose, but like all regenerated cellulose fibres it can shrink modestly on first washing as fibres relax from spinning and weaving tension. Good-quality micromodal garments are pre-washed (or pre-shrunk during finishing) before cutting and sewing, so first-wash shrinkage is minimal. Washing at 30–40°C rather than higher temperatures reduces any subsequent shrinkage. Avoid high-heat tumble drying — while micromodal is more thermally stable than viscose, unnecessary heat over repeated cycles accelerates fibre relaxation and dimensional change.
Is micromodal the same as viscose?
No — micromodal and viscose are both regenerated cellulose fibres but have significantly different properties due to their production differences. Viscose uses a lower draw ratio, producing an amorphous, less crystalline fibre that loses 40–50% tensile strength when wet and is not safe to machine wash. Modal and micromodal both use higher draw ratios and a modified production process that produces much higher crystallinity and genuinely better wet strength. The chain of wet strength from worst to best: viscose (rayon) < standard modal < micromodal. The care consequence: viscose requires cold hand wash only; modal and micromodal can both be machine washed gently.