I used manic panic.. although I must say in red.. but I used it in the shower.. grabbed a strand colored it with my hands(gloved of course.. it was red.. hehe).. let it sit while I soaped.. like less than 5.. hehe and rinsed.. voilá vibrant red hair... and my hair is very light.. just as porous as grey hair.. so it should work.. AND you can add a few to your regular shampoo for "retouching".. could it be more simple.. just gotaa see if there´s a color ok for you..