Lasting up to one to three washes, the BLEACH LONDON Boxed Semi Permanent Dye lets you try something new without the commitment. Developed by an international fashion colourist, Alex Brownsell, the collection temporarily transforms the appearance of blonde or lighter hair types. One box is suitable for short hair or colouring freshly bleached and toned roots. For shoulder-length hair, you will need two bottles. For long hair that is below your shoulders, you will need three to four bottles. If your hair is very thick, it is recommended to add an extra bottle.