Toners are pastel colours used to neutralise unwanted tones in lightened hair e.g. a lilac (often called white) toner can be used to lift yellow tones from bleached hair & blue based toner can be used to lift orange tones. A guide to which toner to use can be seen using the colour wheel - opposite colours neutralise each other e.g. lilac and yellow are opposite each other on the colour wheel below so generally a lilac based toner should neutralise yellow tones in hair). There are other toners like green based ones for lifting out red tones, but your hair perhaps was not bleached enough or is resistant to the bleaching if you still have red tones left in it and therefore the results of your next hair dye may not be as good as you would like. If a toner is left on the hair too long it can take on that shade e.g. bleached hair that was lemon yellow can start to turn pale lilac if the lilac/white toner is left on too long.

Toners can also be used to 'dilute' vegetable based hair dyes such as Manic Panic and Special Effects - this mixing can give more pastel customised shades of hair dye.