Hair toners are often used on coloured hair in order to create shades that may be difficult to achieve by using regular hair dye alone. Hair toners are less damaging to the hair than bleaches or lighteners and are used to lighten hair past the pale yellow stage. Pale yellow is the lightest shade that hair can be bleached to without sustaining significant damage.
Toners are available in permanent, semi-permanent, and demi-permanent varieties. The most commonly used hair toners are the permanent type, which are often applied to bleached or lightened hair to create very pale shades of blonde or white. The only way to achieve white hair without significantly damaging the hair is through the use of a toner. Toners can also be used on darker shades of hair to remove unwanted red pigments.
Toners work by neutralising an unwanted pigment present in the hair. This is done by introducing a toner that is the opposite the offending pigment on the colour wheel. For example, an unwanted yellow pigment can be neutralised by a purple toner, while orange pigments can be removed with blue toner. By using toners, a hairdresser can fine-tune your hair colour in order to achieve the perfect shade without causing excessive damage.
Coloured hair needs to be rinsed thoroughly to remove dye before toner is applied. The hair should be towelled dry so that it is damp, not sopping wet, during application. Toner is mixed with developer in a 1:1 ratio and then applied to the hair starting at the roots in the same way hair colour is applied. Once the toner mixture has been applied, the colour should be checked every five minutes. Leaving the toner on too long could cause the hair to absorb the colour of the toner instead of just neutralising unwanted shades.
Toner can be applied occasionally to coloured hair in order to maintain the correct shade. White hair can sometimes become yellow over time and applying toner can remove the yellow tint and brighten the hair.
Before toner application, it is important to perform an allergy test. This is done by mixing a small amount of toner with developer and applying it to the inside of the elbow. Allow the toner to remain on the skin for 24 hours and then check for any signs of irritation or a rash. If the skin is irritated then the toner should not be applied to hair as it could cause a serious allergic reaction on the scalp.