Space.com with VideoFromSpace account on YouTube, has videos featuring various things related to the activities of the astronauts in outer space. Space.com also provides a special question and answer session if people are curious about the activities of the astronauts in outer space.
In a video about question and answer to the Commander Chris Hadfield of the International Space Station was a little boy asking health-related questions, how to wash their hands when the astronauts were in space. It is actually quite trivial but be interesting and intriguing, perhaps not only for this kid but also many people who want to know how the astronauts wash their hands when there is no gravity inside the ship.
Commander Hadfield also shows a plastic bag labeled No Rinse Body Bath is used for washing and cleaning the body while in the ISS spacecraft. The bag turned out to contain water of different temperatures in the ratio of 2 ounces cold water and hot water 6 ounces. Water mixture resulted in slightly soapy water solution in the bag which can then form a bulb when squeezed out comes water for washing hand.
In the video it appears that the water does not spill out, even forming a gel-like clump together so easily captured and brought to hand to clean. Sparks coming out of water also form granules that hovered around the room. Apparently, the astronauts should not carelessly use the bag as hand washing could splash water float will be attached to the equipment and can interfere with the performance of these tools.
Why just needed a tiny bit of soap? Because in space the water will be quite valuable and limited so you cannot clean your hands with enough water to rinse the soap. For that after using the liquid soap, you can simply wipe your hands with a towel that has been provided.
Want to check the video? Here it is: