Chlorinated water, iron, and minerals from inside your water pipes can tint blonde hair to green.
What to use:
Use a showerhead attachment like Resc-Hue Water Purification System ($120 at sephora.com) to filter unwanted chemicals in the water, and deep treat once a week to keep blonde locks hydrated. TRY Marc Anthony Advanced Color Protect Anti-Aging Night Repair ($10 at Ulta)
Over time, brown hair dye oxidizes on your strands, resulting in an orangey, rust-colored tone.
What to use:
Wash hair with tepid water hot opens the cuticle and lets color seep out. Apply a nonpermanent dye in a cool tone on top of the color you have permanent color once a month to neutralize brassiness. Try GarnierbaShine Color Crème Medium Ash Brown ($8, at drugstore)
Red dye fades faster than other hue; the color particles are the largest and escape the hair shaft more easily.
What to use: