How do you keep a tilley hat from yellowing?

To prevent a Tilley hat from yellowing, store it in a cool, dry place away from direct sunlight, which can cause fading and discoloration. Regularly clean the hat according to the manufacturer's instructions, using mild detergent and avoiding bleach. Additionally, avoid exposing the hat to sweat and oils from your skin by using a sweatband or washing it frequently. Finally, consider using a fabric protector spray to help resist stains and UV damage.