I love this stuff and use it on my white / grey tails. It washes out in 6-7 washes You only need 4-5 drops in a bucket of water after you wash and condition your tail pop it in for about 10 seconds allow to drip dry. I have before and after shots of a white that goes silver white. I also use this on my dogs placing in a bucket a few drops and pouring over can be used the same way on horses 🐴 I make my own blue shampoo by placing a few drops 8-12 in a shampoo of my choice that is clear or white to make highlight / toner shampoo ☺ One bottle of 15 ml goes a long way and can save on cost in keeping your horse that white you like.