Machine wash, very hot
An ISO 3758 washtub showing 90 °C (or four dots), the hottest standard domestic wash temperature, indicating a maximum of 90 °C.
What it means
The figure 90, or four dots, permits a near-boil wash. It is found almost exclusively on robust white cottons and linens designed to tolerate aggressive cleaning and high heat without distortion.
What to do
Use 90 °C only for heavily soiled, colourfast white cotton or linen that explicitly carries this symbol. It is unnecessary for routine laundry and will damage most modern blends, so check the label before selecting it.
How to use this term
Use this washing symbol before choosing water temperature, cycle intensity or whether the item should go in the machine at all.
- Read machine wash, very hot with the other symbols on the same care label; the strictest symbol wins.
- Match the instruction to the garment's most fragile part, including trims, lining, prints and finishes.
- If the label, fabric behaviour and stain method disagree, test a hidden area or choose the lower-risk route.
Common mistake
Treating the hottest setting as a stronger hygiene wash and using it on anything not explicitly rated for the heat. Few everyday fabrics tolerate near-boiling water — it can fade dyes, shrink cotton, and break down the elastane in stretchy blends — and 90 °C is rarely needed over a 60 °C wash, which already handles most hygiene.
For the broader method, use the Whiten yellowed whites and then return to this term when the label changes the safe option.
Related terms
Sources
- ISO 3758:2012 Textiles — Care labelling code using symbols — International Organization for Standardization