Well here’s what’s goin on... she had her hair bleached all over from a different stylist and it is super brassy. She wants to be more ashy and is considering partial balayage as well. I would need to tone the brass, balayage and tone again. I just thought it wouldn’t matter if I tone and bleach at the same time. I’ve see. Stylists do shadow root the same time as the bleach application.
Id be inclined to do a full head scattering of highlights, while these are processing, apply a demi/quasi in between to bring the base down to at least a 6. Then once this is processed, rinse, shodow the root with a 5 again depending on how dark your client really wants to go, and then apply a toner over the mid lengths and ends, that is going to clean up the highlights, blending the two together.
You defiantly don’t need to tone before bleach as you need to lift the hair first to at least a level 9 for the toner if you want the ends a nice ash or beige blonde. I agree with Ronray with this technique sounds like a good service to go with x