Egg oil birthday

How long does it take for Sun-In to ware off? - welling ware stainless

My friend has light brown hair, and I want a little lighter or maybe a little light shows are another natural coloring. We found the product of Sun-In, which is a spray on hair product, the light is the SO. What we want to know is if the sun really works well? Also, how long does it take to eat? It is very important that the return to its natural color in a month or two, or when school starts again.Thanks!