I this afternoon I bleached my hair to an even white-blonde. It was the same coloration as it always is after bleaching and I could not see any dark spots or differences in "yellowness".
So when I applied Crazy Color's Grey (#42) I was at a loss as to why most of my hair turned a purplish brown and the rest a greenish grey. (Also worth noting that the root area of the brownish hairs is a light honey-blonde color).
Review: 0 stars. Don't buy.

Questions:

Anybody know what caused this? How to cover it evenly? I'm thinking about a temp black but once that starts fading it will most likely look disgusting. :(

Photos below.

Even though this didnt work out for you - you should do this as a guide

It baffles me how a grey can turn brown...

Was it supposed to be used as a toner? I wonder if leaving it long like you would a dye is why it went funky colors - rather than just leaving it on a few minutes to tone it to a gray shade. Still not entirely sure why it would go brown though.