Not an hairdresser OP, but veteran of many a box dye mistake! 😂 I now order salon products online and do my hair myself… and mostly it comes out as i planned!
Exactly what this PP said. If you’re using something like a 7.3 it’s a level 7 so dark blonde but the .3 is golden tones, so will end up looking warm.
You might want to try something with .1 which is ash toned… but be aware that golden tones reflect the light, whereas the ash doesn’t in the same way and therefore looks darker to the eye. So a 7.1 would look darker than a 7.3 even tho the level is the same. If you want super ashy and for your hair to still look light, you’d probably have to bump up the level. There is a risk of completely ashy hair looking a bit flat, so some ranges have two decimal points eg 7.13 to try and mitigate that.
If you’re using permanent colour box dye the developer is likely to be higher (but you might have to look at the box and it might tell you the volume but not always). If the developer is higher, eg 20% it’ll lift the base colour/lighten it. But it can only do so much, so usually a permanent box dye can lift your level by 1-2 levels at a push… but it’s easier if the tone you want is warm because the underlying pigments in your hair as you lift are warm- yellow in v blonde hair and orangey in darker blonde/brown. So as an example about ten years ago I used to use an 8.34 box dye and it came out really well on my natural level 6/7 hair because the underlying tone was warm- think strawberry blonde. If I was aiming for an 8.1 I don’t think it would have been successful because of the warmth in my natural hair- it would have looked awfully brassy.
The Demi permanent colours have a lower volume, so won’t lighten as much… but personally I’ve found they can lift 0.5-1 level and then as it washes out it leaves a warm/orangey hue as the colour goes, leaving behind the underlying lifted pigment. Eg when I toned my highlights with loreal dia riche (slightly longer lasting Demi) overtime and repeated applications, it lifted my base colour and so when the tone had washed away my hair was slightly lighter/brassy hue. I knew it was a risk because it had a stronger developer/ I was trying to balance out strong enough to cover greys vs not ending up too brassy over repeated applications vs not having to redo it every 5 min!
I’ve now moved to shades eq as that has no lift, and therefore you don’t end up with the brassiness a few weeks later… but that means you cannot lighten the level at all, and it doesn’t last v long, 6w max. The NB range is good at covering grey. It does have a developer but it’s super weak so no lift.
Purple shampoo is to knock out yellow tones- they’re opposite on the colour wheel. To cancel out orange you need blue shampoo. I haven’t used any myself so can’t personally recommend any I’m afraid.