Hello, I have a request for an expert or someone who understands this topic. I have to highlight 2 ladies .... the first one has a hair color ashen blond-hair is thinner, weaker in cross section and the length is shoulder length, the second lady has hair dyed every month to a darker brown color (Schwarzkopf from a market) -hair is also thinner , of weaker cross - section, but the length of the hair is about below the shoulder blades. Both want a classic highlights in foil, each with only about 6 "packages". My point is how long I should leave a mixture of peroxide and highlight powder on this hair so that the hair does not "fly". peroxide: http://www.vlasy-kosmetika.cz/lovien-essential-oxig-6-peroxid-k-barvam-a-meliru-na-vlasy-lovien-1000ml-6843.html meling powder: http: // www.drogerie2.cz/fotky137/fotos/_vyr_3678Melir_v_sacku.JPG I would also like to ask if it does not matter that I use these 2 products even if there are other brands. Thank you in advance for any answer.