Question: How did you make that massive bubble!?

Grant Campbell answered on 12 Mar 2013:

I had a massive bubble wand! I also created the bubble slowly, and humidified the atmosphere first (by squirting water into the atmosphere) – dry air is an enemy of bubbles, as it makes them dry out and pop. And I used a good bubble solution, which has a good balance between viscosity and surface activity (a complicated concept that I can’t explain easily here, but it’s what allows dishwashing liquid to clean and also to create bubbles). Basically, molecules that are surface active have one part that likes to be in water, and another part that likes to be in something very different from water (something “non-polar”) such as fat or air. Such molecules, called surfactants or detergents or emulsifiers, help water to clean fat, and help bubbles to form. You can’t blow bubbles with pure water – you need some surfactant in there.

By the way, what I’m doing in that picture is stabbing the bubble with a knife! If the knife is dry, that makes it pop, but if the knife is dipped in the bubble solution first, you can stab the bubble and it doesn’t pop. I was using this to demonstrate a possible way of making wholemal bread nicer! Bran particles in wholemeal bread damage the bubbles in the bread, by behaving like the knife and popping them. Coating the bran particles with surfactant could prevent this and make wholemeal bread lighter and nicer!

Thanks for your question.