You have invested in a good merino garment. Then it shrinks in the machine, or loses its shape after the first wash. It is one of the most common frustrations with wool clothing.
What actually damages wool: heat and mechanical stress
Wool fibres are covered with microscopic scales—almost like fish scales under a microscope. When these scales are exposed to heat and mechanical friction (such as in a washing machine), they lock together and shrink—a process called felting. It is irreversible.
This means that the two enemies of merino wool are: hot water and agitation. Remove these, and the wool will last for years.
How to wash merino wool correctly
- Machine wash: Use a wool cycle (gentle, low speed), maximum 30 degrees. The vast majority of modern merino garments can withstand this.
- Hand wash: Cold water, gentle movement. Do not wring or rub. Let the garment absorb the water, move it carefully, rinse.
- Detergent: Use wool-specific detergent. Regular detergent contains enzymes that break down wool proteins over time.
- Rinsing: Rinse at the same temperature as the wash. Temperature shock can trigger felting.
- Drying: Always dry flat. Never hang wool to dry—it stretches under its own weight. Never tumble dry.
You probably wash too often
Wool is naturally antibacterial. It does not smell after one or two wears under normal use. A wool garment worn for one day can usually be aired out (lay it flat, preferably outdoors in fresh air) and be ready for the next day.
The less often you wash, the longer the garment lasts. Aim to wash after 5–10 wears, not after every wear.