Acrylic study using Vaseline. It's similar to negative painting, on which I screwed the pooch. Darker, background colors should have been covered as well as most of the already painted leaves, thus only allowing one color to cover the bottom. The flower petals also gave me a good pissing as I wanted to add a highlighted glaze which didn't work as it was still too thin. I used a hogs hair brush to brush the vaseline over the spots where I wanted it as well as a cheap pastry bag to pipe it in thin lines.
I can't really see this as applicable for anything other than abstract bullshit, but that's just my personal opinion on this trial and error experiment.