Colouring backgrounds by firing a gelled-flash at them has been a lighting trick I’ve been using for a while. These days my preference is to use a paper grey background as the ‘base’ background. This shot used a thin white sheet with a gelled flash behind it. My goal was to have the coloured light wrapping around the model as you can start to see on the inside of her arms. The problem with this shot was that I didn’t get enough separation between the foreground and background, so the flash hitting Kari started to interfere with the light hitting the background sheet. It’s not too bad in this image but you can see a difference between the colouring on the top left and top right.