Basic color theory will show that a blue base is needed to make a purple shade, the blue undertone in any purple shade is the last to fade out. This kind of color needs to be topped up every couple of weeks to stop the fade. Make sure you aren’t using a hair care routine that strips out your color, see more information here. If the issue is the color blue staying in the hair when you want it removed you should use a sachet of Crazy Color® Back to Base Remover. This will remove any unwanted color and take the hair back to shade it was pre-lightened to. If the issue is the color blue staying in the hair when you want it removed you should use a clarifying shampoo with warm water this will fade it to a pastel blue quickly. You should then let the color fade naturally or consult a hair stylist to remove it. You can also at this stage add a pink or red Crazy Color® over the pale blue to neutralize the tone leaving you with a whole new color!