Orange looking, brassy hair colours are a potential problem that comes from lightening a hair colour. When making a colour lighter, such as dying hair blonde, the brassiness occurs when the colour was too light, the wrong dye colour for the original hair colour, dye was not left on long enough or even the water has iron in it. Fortunately, there are methods of fixing the brassy tones and getting the colour out of the hair for a nice colour tone.
Use a purple or blue shampoo and conditioner on hair. These are often labelled as shampoo or conditioner for blonde hair and they are effective in neutralising the colours that cause brassiness.
Put an iron filter in the house water supply. Heavy iron in water can result in brassiness a few days after dying the hair as iron deposits on the hair during normal washing. According to Become Gorgeous, the only way to eliminate brassiness that comes from iron in the water is putting in an iron filter.
Dye the hair with an ash coloured dye such as ash-blonde. When a brassy colour comes out after dying, using an ash-blonde or ash coloured dye will help neutralise the brass appearance. Otherwise, dye the hair back to the original darker colour.
Apply a toner to the hair. Toners are semi-permanent dyes rather than permanent and work to hide the brassy colour for a short term period. They will require reapplying after a few weeks to keep the brassiness from showing later.
Avoid brassy hair in the first place by selecting appropriate dye colours. Stay away from red-toned blondes or colours that are more than three shades lighter than natural hair colour to avoid brassiness.