Sooo if I stop dyeing my hair with permanents will it get thicker or is it just bleach that does this?
A semi is better over long term. If you always use permanents you'll probably end up damaging your hair anyway because a majority of them have peroxide in, which is basically bleach. If you check some packs you'll see that even some black dyes contain peroxide, just to help it adhere to your hair.
Roxy, that's a great idea. Something I hadn't thought of.