What's the point of hair colour strand tests?

I was just wondering...my step-mom went to dye her hair again, but there was a piece of paper mentioning "hair strand tests," I didn't have a chance to take it away and read it, so I thought that I would ask.

Thanks!

What's the point of hair colour strand tests?

its to see how the dye reacts to your own hair, to see how long you need to keep it on to get the color you want. i think its also to make sure youre not allergice to the dye. its important to time the dye to make sure your hair doenst turn out orange!

What's the point of hair colour strand tests?

it is so you can see if you are going to react with the dye and also you can see what color it will be

What's the point of hair colour strand tests?

It's to see how long you need to leave the dye on because everyone's hair is different depending on how many times they've colored it before. It's also to see what color the dye will turn out on your hair before you actually do your whole head.

The arm test is to make sure you're not allergic to it. You should always do this because I've heard horror stories and seen some nasty pictures of swollen faces.