Woolmark describes AgResearch and SIFO research comparing how long base layers, mid-layers and socks could be worn before odour prompted laundering. The volunteer-based work found differences among Merino wool, cotton and polyester garments. It also estimated energy use associated with the resulting wash patterns.

Odour-Based Wear Trials Link Fibre Choice With Laundry Frequency

The result concerns the study's garments and odour-based decisions rather than one compulsory schedule for everyone. Stains, hygiene needs and garment instructions can require washing sooner. Its practical contribution is showing that in-use fabric properties can influence laundering demand, which is a separate factor from the original manufacturing process.