While vibrant, pop-art colours like scarlet, copper, and violet are indeed stunning, they lose their impact more quickly than colours that bring about a more subtly altered state. By all means, if you're okay with the increase in upkeep, go for it! And remember to give it a tint rinse, which will give your colour a fresh life and help maintain it healthy, even, and vivid, you'll extend the looks of any permanent hair colour. Choose a neutral hue that will add lustre and depth to your present colour without drastically altering it if you're seeking for little upkeep. Rainbow hair often needs the greatest upkeep since it ages more quickly than conventional hair colours.  If you don't lighten your hair beforehand, particularly if you have darker hair, a rainbow hue may not show up precisely how you want it to.