I am tanning a client this evening, she has previously had a Sienna 8.5% that I used on her 2 weeks ago which turned out perfect for her skin tone, I want to try the Nouvatan sample on her this evening I have the 8 and the 12 can any one who is familiar with the solution give me some advice on what to use, my instinct is to try the 8% but I am judging that by Sienna's 8%.....