Methods for Tan Lines

Hi guys! I have a client that has tan lines on her chest. The un-tanned skin isn't really super pale, but the lines are noticeable enough when she wear a strapless dress and she has a special even coming up. I'm not able to alter the spray size on my gun, so from doing some research and talking with the people at Sjolie it was suggested to me to apply the solution first with a cotton ball to the tan lines, let dry, then spray everything as normal. I just tried this with my client (this is the 2nd trial tan) and am a little nervous since I've never used this method before. I didn't think the bronzer would blend after I applied the solution, but the areas where the tan lines were covered are a lot darker.

I was wondering if anyone else evens out tan lines this way and how it's turned out for them. Or if there are any other techniques out there that you guys are having success with? Thanks!