Some wild pictures here, depicting a veritable sea of foam. These airplanes will definitely be clean after that, but will they work? For example, this page describes how to wash smaller planes, but is that how they wash the larger ones?..
Of course, there is another way, too:
"Aircraft assigned to the 403rd Wings of America's Air Force now have a new purpose-built wash system, which blasts 2,000 gallons of water per minute, emitting 150 pounds of pressure from each of its 40 nozzles" (image credit: 403 Wing)
Here is a cool turret method (here shown de-icing the plane):