It is one of the most common mistakes, and one of the most costly for the lifespan of linen: overdosing detergent. A seemingly harmless gesture, which costs the linen several years of use.
Why dosage matters so much
A detergent works through cleaning agents and surfactants. Its role: to lift soiling and hold it in suspension in the water so it is carried away at the rinse.
When you dose too much, the excess surfactants stay on the fibre. They form an invisible film that greys the white, dulls the colours and tires the textile.
The golden rule: 50 ml per standard machine
For a 6 to 8 kg machine, loaded normally: 50 ml of liquid detergent (around half a cap). That is the baseline.
The 4 factors that change the dose
- Volume of linen: half load → 25 ml, large load → 70 ml.
- Soiling: lightly soiled linen → -20 %, very soiled linen → +20 to +30 %.
- Water hardness: hard water → +10 to +25 %.
- Temperature: at low temperature, +10 % for moderately soiled linen.
Special cases
Hand washing: 20 ml in 10 L of lukewarm water. Soak 10-15 min, rub, rinse thoroughly.
New-generation washing machines (10+ kg): follow the manufacturer's guidance, often 20-30 % less detergent.
And the fabric softener?
25 ml per machine in the softener compartment. A third of a cap. There is no need to increase the dose for a stronger scent, the olfactive signature settles through repetition, not concentration.
This is what we calibrated for MÉMOIRE, our signature softener.
A tip from hotel laundries
Rather than dosing by the cap (and going over, because it is easier), mark the level with a pen on your cap at the standard dose. Or use a graduated 50 ml syringe.