Handwash (recommended) or machine-wash your merino wool fabrics on a cool gentle/wool cycle using a wool detergent.
Do not bleach. Avoid fabric softeners.
Simply lay flat in shade to dry.
Kim's personal 5-minute handwashing tip:
Soak for 5 minutes - in a basin filled with cold or lukewarm water + your wool detergent or mild shampoo (wool is hair after all). Agitate water as needed.
Do not scrub.
Rinse. Do not wring tight.
Then lay flat in shade to dry.