Box dye to cover greys?

[Zhougzhoug]

I have very dark brown hair and I really like its natural colour so I don't want to change it. It has some interesting undertones which I'd always liked.

Now I have a noticeable few grey hairs, but nowhere near the 10-15% grey my hairdresser said to get to before I started professionally colouring it. Probably 30-50 hairs, mostly in two or three clusters. If I did a box dye in a lighter colour, say mid-light-brown, would that cover the greys without changing my natural colour? Would it still fuck up my hair condition? I'm thinking Josh Wood or a decent brand like that.

I don’t know for sure but I used what I thought was a good match for my dark brown hair but it was actually a bit lighter. So my whole hair ended up lighter. Took ages to grow out.
I just target the greys with the root touch up now!

I have thick, dark brown, long hair and likely have far more grey than you. I've used Clairol casting colours for years. Its a semi and supposed to last 40 washes. I've never gone that long without reapplying one to know though. My issue with permanents is that when they grow out, you are left with a sharp line of colour which the semi doesn't leave.

With that brand, I always buy a much lighter colour than my hair though, because they come out darker than you'd expect. As said, my hair is dark brown, but I use light brown casting colour! Sometimes I use a chestnut colour for a bit of difference- but always a lighter colour than my natural hair colour.

Agree with @SM4713 that you generally need a lighter shade than you'd think. I'm naturally a mid-dark brown but with semi permanent I used lightest brown shades.

And yes, all permanent dye involves peroxide. Semi does too, just weaker.

Henna washes will simply give your natural brown a gloss, but colour your grey into a reddish highlight as will Holland & Barrett's Its pure.
You could try any of the semi-permanents without bleach and leave them on for less time.

My hairdresser just touches in my parting and the front of my hairline to match my natural colour.