Alongside its other natural performance properties, wool provides excellent protection from the sun’s UV rays. Even when completely untreated, wool absorbs radiation from across the entire UV spectrum, much more effectively than many other materials.
When categorised in Ultraviolet Protection Factor (UPF) terms, woollen garments typically have a significantly higher rating than, for example, the average of UPF of 10 for a cotton t-shirt. Depending on the density of the fabric and how it has been treated and/or dyed, woollen apparel usually has a UPF of between 20 and 50.
It is worth noting that UPF does decrease a lot when any fabric is wet.
Manufacturers of performance garments often use a treatment to enhance the UV protection that already exists in wool. When purchasing woollen clothing, it is always worth verifying whether any UPF rating has been boosted with a treatment, as that may reduce over time. However, the public can have peace of mind that all wool does naturally provide a degree of permanent UV protection.