Anatomy of a Shot: Soap Bubbles, Pebble and a Square

This is the anatomy of the process of creating an image for Utata's Iron Photographer 91 project. The elements to be included were:
1 - soap
2 - stone(s)
3 - square format
I tried to challenge myself to create something that would be outside the realm of obvious compositions - e.g. using pebbles and round bars of soap in some visually appealing composition with soft light. I first decided to get away with the soap bar entirely - and instead to use soap bubbles. No particular reason other than the fact that I had one of those soap bubble producing gizmos around my house. Still fits the theme and it allows me to do something weightless. From weightless, the concept evolved to suspended - I'm going to suspend a pebble (also laying around my house from a previous trip to the beach)- kind of like a stony fish in an aetherial square of bubbles.
Having the concept nailed, I started thinking about the execution. First - I needed the appropriate background. Black was the obvious choice - I wanted the pebble to stand out. So I set up my black muslin background, lit the suspended pebble from both sides with SB-28s and produced a few test shots. The strobes were snooted to prevent spill on the background and lens flare. The pebble had a nice translucence to it - so I wanted the expose it to make that visible. With my D700 on a tripod and outfitted with a cable release, I started blowing the bubbles. The first few shots revealed a disturbing fact: while the pebble was properly exposed, the bubbles were just not showing very well against the black background. They were just catching the reflections from the two strobes - and they looked like eyes of creatures lurking in the dark.
To solve the bubbles problem - I needed some white to be reflected off their edges for definition. So I needed some white just outside the frame - easily accomplished by changing the background muslin from black to white. I still needed the background for the shot to be black, so I placed a sliver of black fabric on top of the white, just for the portion visible through the viewfinder. With the new background arrangement in place, I also needed to change the lighting scheme. To get even edge illumination - I decided to place one of the strobes behind the background - to create that wraparound effect often used to illuminate wine glasses and the like.
After some fine-tuning, the remaining work was to fire enough frames to get a composition I was happy with. I could not control the flight path of the bubbles - although after enough trials I became quite proficient at shooting most of them in focus and close to the pebble.
The post production involved just minor retouching (sharpening, increasing contrast) and of course, the square crop.