Updated: Sep 24, 2018
Silver toners can be put on bleached hair to give a lovely silver. However, sustainability can be an issue. A tip I suggest you try is purchasing a silver shampoo that is heavily pigmented blue and leaving the shampoo on your hair for 5 minutes the first time to see how you get on. If this isn't visible enough for you then you should try leave the shampoo on for 10 minutes next time. The maximum recommended time I would leave the shampoo on the hair is 20 minutes.
For people who have highlighted hair, it will stop the colour from going brassy. The colour will remain a cool, clean blonde.
For people who want silver/white hair either as a fashion colour or natural white/grey hair, it will brighten the colour and prevent any yellowing.
Fewer toners will be required to keep the colour if you use this shampoo - leaving it on for 5-20 minutes.