There is a hand cleaner that is used instead of soap by some people. The bottle has a liquid substance in it and when one presses on top of the bottle a bubble foaming substance comes out. The bubbles kind of evaporate over time if left untouched. People then clean their hands with this mass of bubbles by rubbing there hands together until the bubbles disapears. On Shabbos: Is there a problem that the liquid turns into a mass of bubbles when pressing on the top of the bottles spout? Is there any problem of rubbing the bubbles together on the hands on shabbos for cleanliness? thank you for your help
Although Rav Moshe Feinstein zt”l was stringent with this, most authorities allow using this soap on Shabbos, because foam such as this which dissipates after a short time cannot be considered to have been “created” on Shabbos, and there is no problem of Memareiach because it is considered a liquid.