* Artificial Red Undertones: Many brown hair dyes, especially permanent ones, contain red and orange undertones to give the brown color depth and warmth.
* UV Ray Degradation: The sun's UV rays break down the artificial color pigments in the dye. Brown dye pigments are larger than red/orange dye pigments. This means that the brown and black tones are more likely to fade, leaving the smaller red/orange pigments behind.
* Natural Pigment Exposure: If you have natural warm undertones in your hair, the sun might also lighten the dyed hair enough to reveal those undertones.
* Hair Porosity: Hair that's more porous (damaged, dry) tends to lose color faster, making it more susceptible to the effects of the sun.
How to prevent it:
* Use color-safe products: Shampoo, conditioner, and styling products designed for color-treated hair can help protect the dye.
* UV protection: Apply hair products with UV filters or wear a hat/scarf when spending prolonged periods in the sun.
* Avoid excessive washing: Washing your hair too frequently can strip the dye.
* Cool water rinses: Washing hair with cool/cold water can help to seal the hair cuticles and lock in color.
* Gloss or Toner: Use a gloss or toner to neutralise any brassy tones
* Professional advice: Consult with your stylist for specific product recommendations and color maintenance tips.