HELP: Removing brasses on brown hair : 7.11 or 7.81??

I think dying an ashy, cool color over the brassiness would make it a weird, muddy color. I wonder if a purple/violet based toner would help out with the brassiness. As to how long you would need to wait, I would say at least a month to be on the safe side to not damage your hair. Between that time you could use a purple shampoo to help with the brassiness.

Your hair is very dark naturally, it's hard to tell from the photos but I'd say a level 3 maximum. With 30vol, you could get up to a level 6 result (3 levels lift) but 30 vol will always bring out a lot of brassiness, so if you want cool tones you need to add a cool mix tone which would darken your hair by another level (ash is always dark), giving you a level 5 result. I don't know the number/letter system for CDC, but initially it would have been better to use a level 6 with a blue base and with 4g of their blue mix tone per tube of dye used. A higher level doesn't have enough pigment to work well on the darker hair.

I wouldn't use the 7.11 (.1 is ash) because ash won't be enough to cancel out the orange tones, you need blue. Blue in wella is /8, they also call it pearl. In Illumina you should use the 5/81. If you think it might be too dark you might be able to get away with a mixture of 5/81 and 7/81. You should use the Color Touch 1.9% developer with it as you don't need lift.

On this forum we do recommend waiting a month between peroxide processes as double processing is very damaging on compromised hair since it takes around a month for damage to show so you might not realise you pushed it too far.

Personally, I do a double process when I'm taking my hair to natural shades of blonde using permanent colour with 1.9% developer straight after bleaching. Semis don't have the same shiny, multitonal, slightly translucent result that I want. It's not for everyone though, it depends on your hair condition and how much you've processed it in the past. If you've only used the 30vol once and nothing else on your hair before it might be alright to go in with the Illumina and 1.9% straight away but I can't recommend it as I don't know your hair condition.

Thank you Kababra and Miss_Bluey for these explanations, it helps a lot!

I wouldn't use the 7.11 (.1 is ash) because ash won't be enough to cancel out the orange tones, you need blue. Blue in wella is /8, they also call it pearl. In Illumina you should use the 5/81. If you think it might be too dark you might be able to get away with a mixture of 5/81 and 7/81. You should use the Color Touch 1.9% developer with it as you don't need lift.

I only mentionned 7.11 because it's Koleston and they say that it covers much more than Illumina. But based on your opinions, I'm going to use a mix of 7.81 and 5.81 with a 1.9% developer, I'll wait a month before that, nourishing my hair and applying masks to reduce the damages! Since I double processed my hair (a second application immediately after the accident, repeating this time only a 7.1 with 30volumes...), actually I might have pushed it too far...

I still have a question: for this second application, should I start with my roots first? I'm okay with having an ombré (tie and dye) effect, that's even what I'm planning for to avoid colouring my hair too often.

Thank you a lot again.