Fibre Care Reference
Every fibre the Wash Temperature Guide, Shrinkage Calculator, Drying Time Estimator, and Stain Removal Guide cover, in one table — safe wash temperature, expected shrinkage, recommended drying method, bleach tolerance, and how a protein stain should be treated.
Fibre, wash temperature, shrinkage, drying, bleach, and stains
| Fibre | Safe wash temp | Cycle | Shrinkage (first wash) | Recommended drying | Bleach tolerance | Protein-stain rinse |
|---|---|---|---|---|---|---|
| Cotton (pre-shrunk) | 30–40°C 86–104°F | normal | 3.9% | Tumble — medium heat ~2.3h for a 3kg load | Chlorine bleach is fine on whites and holds up to regular use. Use an oxygen (color-safe) bleach on anything dyed — chlorine strips color. | cold |
| Cotton (not pre-shrunk) | 30–40°C 86–104°F | normal | 7.8% | Tumble — medium heat ~2.3h for a 3kg load | Same tolerance as pre-shrunk cotton — chlorine bleach on whites, oxygen bleach on colors. Whether cotton has been pre-shrunk affects how much it shrinks, not how it responds to bleach. | cold |
| Linen | 30–40°C 86–104°F | normal | 5.2% | Tumble — medium heat ~2h for a 3kg load | Tolerates occasional chlorine bleach on white linen, but repeated use weakens the fiber faster than it does cotton. Oxygen bleach is the better routine choice. | cold |
| Wool | 20–30°C 68–86°F | hand-wash cold | 6.5% | Air-dry ~11.7h for a 3kg load | Never use chlorine bleach on wool. It's an animal protein fiber, and chlorine dissolves and yellows protein the same way it damages hair. Oxygen bleach only if the care label allows it, well diluted, and only after testing a hidden seam. | cold |
| Silk | 20–30°C 68–86°F | hand-wash cold | 5.2% | Air-dry ~6.3h for a 3kg load | Never use chlorine bleach on silk. Like wool, it's a protein fiber that chlorine yellows and degrades. Oxygen bleach only if the label explicitly allows it, heavily diluted. | cold |
| Polyester | 30–40°C 86–104°F | delicate | 1.3% | Tumble — low heat ~2.1h for a 3kg load | Chlorine bleach is generally safe on plain white polyester but rarely needed. Oxygen bleach avoids the faint yellow-gray tinge chlorine can leave on some synthetic finishes. | cold |
| Nylon | 30–40°C 86–104°F | delicate | 1.3% | Tumble — low heat ~2.1h for a 3kg load | Chlorine bleach tends to yellow white nylon rather than whiten it. Oxygen bleach is the safer default. | cold |
| Acrylic | 20–30°C 68–86°F | delicate | Not modeled | Tumble — low heat ~2.1h for a 3kg load | Oxygen bleach only — chlorine bleach can yellow and weaken acrylic fibers. | cold |
| Spandex / Elastane Blend | 20–30°C 68–86°F | delicate | Not modeled | Tumble — low heat ~2.1h for a 3kg load | Avoid chlorine bleach entirely — it breaks down elastane's stretch with repeated exposure. Oxygen bleach at the dose on the product label is safe. | cold |
Wash temperature, shrinkage, and drying figures are computed by the same calculator logic used on the Wash Temperature Guide, Shrinkage Calculator, and Drying Time Estimator — shrinkage is shown for a medium-heat tumble dry, and drying time for a typical 3kg load. Silk borrows the drying-time calculator’s “synthetic” bucket, the closest match for a thin, low-absorbency fibre it doesn’t model separately. Bleach tolerance is written directly — no calculator here touches bleach.
Never mix bleach with ammonia or an acid
The single most important safety note on this page has nothing to do with any specific fibre: never combine chlorine bleach with ammonia, and never combine it with vinegar or any other acid-based cleaner. Mixing bleach with ammonia releases chloramine gas; mixing it with vinegar or another acid releases chlorine gas. Both reactions happen at completely ordinary household concentrations, and both are genuinely dangerous in the small, often poorly ventilated space of a laundry room or bathroom. If you ever smell a strong chemical odor after combining cleaning products, leave the room, ventilate it, and don’t go back in until it’s cleared — and seek medical advice if anyone is coughing, short of breath, or has burning eyes.
This matters most exactly where the bleach-tolerance column above says chlorine bleach is fine: a whites-only cotton wash is also where a well-meaning “stronger stain fighter” mix of bleach and a second product is most tempting. Keep bleach on its own — one product, one step, rinsed and finished before anything else touches the fabric.
Why protein fibres and cellulose fibres take bleach so differently
Cotton and linen are cellulose fibres — plant-based carbohydrate structures that chlorine bleach can whiten without dissolving, which is why a white cotton sheet can take an occasional hot wash with chlorine bleach for years without falling apart. Wool and silk are protein fibres, built from the same kind of amino-acid chains as hair and skin, and chlorine doesn’t just whiten protein — it breaks it down, leaving wool brittle and yellowed and silk weakened and dull. That's a structural difference, not a matter of degree, which is why the guidance for wool and silk above isn’t "use less bleach" but "don’t use chlorine bleach at all."
Oxygen bleach (the active ingredient in most "color-safe" or "all-fabric" bleaches) works by a different chemistry — releasing hydrogen peroxide rather than chlorine — and is gentle enough for most fibres including wool and silk in small, diluted amounts, though it’s also meaningfully weaker at actually whitening than chlorine bleach is. The two aren’t interchangeable substitutes for the same job; they're different tools with different limits, and picking the wrong one is either ineffective (oxygen bleach on a set-in stain that really needs chlorine) or damaging (chlorine bleach on a protein fibre that can’t tolerate it).
Frequently Asked Questions
Where do the numbers in this table actually come from?
The wash-temperature range and cycle, the shrinkage percentage, and the drying time are all computed live by calling the same functions behind the Wash Temperature Guide, Shrinkage Calculator, and Drying Time Estimator — nothing here is a separately typed-out number that could drift out of sync with those tools. Only the bleach-tolerance column is written directly, because none of this site's calculators model bleach at all.
Why do acrylic and spandex/elastane blends show no shrinkage percentage?
The Shrinkage Calculator simply doesn't have an entry for those two fibres — it covers cotton (pre-shrunk and not), linen, wool, silk, polyester, and nylon. Rather than borrow polyester's number and imply it's an acrylic-specific measurement, this table shows "not modeled" honestly. In practice, both fibres are heat-sensitive synthetics that hold their shape well at the wash and dry temperatures recommended here, but neither has a published first-wash shrink figure behind this particular tool.
Is it ever safe to mix chlorine bleach with ammonia or vinegar to make a stain treatment stronger?
No — never combine chlorine bleach with ammonia (it releases toxic chloramine gas) or with vinegar or any other acid-based cleaner (it releases chlorine gas). Both reactions can happen at ordinary household concentrations and in a poorly ventilated laundry room or bathroom that's genuinely dangerous. If a stain routine calls for bleach and a second product, treat them as separate steps on separate days, never combined in the same container, spray bottle, or wash load.
Why does this table only show the stain approach for protein stains?
Protein stains — blood, sweat, egg, dairy — are the most time- and heat-sensitive of the six stain categories the Stain Removal Guide covers, so they're the clearest single example of "what actually changes by fibre." The guide covers oil-based, tannin, dye/ink, wax/gum, and mud/dirt stains too, each with its own first move.
My garment's care label disagrees with a number in this table — which do I follow?
Always the care label. It reflects testing done on that specific fabric, dye, trim, and construction. This table gives sensible defaults for a fibre in general, which is exactly what you need when a label is missing, faded, or cut out — not a reason to override an explicit instruction that's still readable.
General guidance only. Ordinary washing cleans fabric — it doesn’t sterilise it — and this page makes no medical or disinfection claims. Always follow the garment’s own care label first; it reflects testing this general reference can’t see.
Use it with
- Wash Temperature & Care Guide — get a full range, cycle, and spin speed for any fibre, adjusted for soil level and color.
- Fabric Shrinkage Calculator— predict a specific garment’s finished size, or work backward from a target measurement.
- Drying Time Estimator — get a time estimate for your actual load weight rather than the 3kg reference load shown here.
- Stain Removal Guide — the full method for all six stain categories, not just the protein example shown above.