17 year old boy going for silver / white

What toners you need will depend on the shade you actually get when its bleached. I'm sure you know this, but it'll hopefully be a pale yellow, inside of a banana colour.

However, a great investment is bonacure silver shampoo 🙂

UPDATE
Hair bleached. Retaining a very light plat blonde

My hairdresser put a toner in which made it go the exact colour I wanted but after about an hour or two it reverted back to this colour and I also have a shampoo that makes it into a perfect white but only for 10-15 minutes

Hmm. Well that's a new one on me. I have no idea how that would happen.

Unless it's changing lights? My hair is close to white at the moment (my hair will never go proper white unless it's highly damaged) and in some lights it's greyish and some it's yellowish.

Found out the problem, roots need one more bleaching, any way around this anyone know?

It would help if you can show us a picture. You probably just need to leave the shampoo on longer. Which shampoo are you using?

Still, it working for 10-15 minutes still doesn't really make sense to me...

Yeah sorry here's a picture right after the shampoo

Schwarzkopf Bonacure Color save silver thank you for the help 🙂

Probably worth mentioning it's in my hair for less than a minute as the application reads ' blonde hair massage into wet hair and rinse out immediately grey hair: leave in for 2-3 minutes then rinse ' although I can't tell if it means FOR that colour or TO GET that colour

You might be unable to get fully white hair like me, it just never happens as getting the exactly the right base colour doesn't ever happen. Unless it's pretty much fried.

However, try leaving it in for longer. I don't leave it on for longer than a few minutes as it goes too grey, or lilac, but others swear by leaving it in for anywhere from 4 - 30 minutes.

I left it for an hour to get a really silvery white.