pH indicating soap bubbles (Ben Krasnow - new channel name!)

I thought it would be cool to have a colored soap bubble that responded to changes in pH. I concentrated some phenol red (pH indicator), and mixed it with commercial bubble solution. Unfortunately, it was not dense enough to actually show its color. While investigating this, I noticed that normal soap bubbles lose their color as they become thinner (due to evaporation) and eventually burst. I tried to get footage of this color loss, but the bubble will not stay in the same place! I started to develop a method to partially fill the bubble with helium to make it neutrally buoyant.