As in body soap, shampoo, dish soap, leather seats foam, toothpaste, car wash, …
All are different surface with different “dirt” and yet the foam is constant.
Is their any chemistry related reason that bonds cleaning any surface with something happening during foaming?
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It’s just what people expect. Real soap (fat and lye), used for so long before detergents came about, produced foam. So people associate the foam with cleaning.
However, detergents for dishwashers and washing machines for cloths are formulated to keep foaming to a minimum. With the great amount of agitation in those machines, a detergent that foams will likely fill the whole machine full of foam, and then the foam will overflow out of the machine.
Soap is whats called a surfactant, the issue with water is its only able to wash off whats water soluble (hydrophilic), there are things like oils that are not water soluble (hydrophobic). Surfactants are chemicals that have a side that is water soluble and another that isn’t, the side that isn’t water soluble is able to stick better to non water soluble chemicals like oils, and wraps them in usually small bubbles to which lets water carry them away. [Heres a diagram showing this.](https://media.beckman.com/-/media/stock-images/resource-center/images/micelles_liposomes-2021-11.jpg).
They also really like to kinda build themselves like legos on a microscopic scale, the hydrophilic heads are attracted to each other and attracted to water, the hydrophobic tails are attracted to each other as well to a lesser degree, so they arrange themselves sideways, can curve a little to make these small shells, bubbles in other words.
These bubbles on a smaller scale work also on a larger scale, which makes the foam we know. Bubbles are a mix of this and some water that gets attracted to the heads and also helps pull the different soap molecules together.
This isn’t always desirable though, for example dishwashers don’t particularly like foam cause it interferes with the spraying water that really washes the food, they mix some soap into the dishwasher soap but its a special non foaming one (we can make special surfactants that can make these bubbles on a smaller scale but can’t on a larger scale).
Soaps are long chains of fats that have a polar and a nonpolar end. The polar end is attracted to water and the non polar end is not.
This let’s them grab fats and other non polar substances on your skin and drag them away with the flow of water. And also it means that when you agitate them they naturally form layers where the polar ends are out and the nonpolar ends are facing each other. When they form these around some air that is a bubble. And since agitating them always introduces air you’re going to produce some bubbles.
There are two things to note here. The visible foam you see is a product of the chemical structure of soap (surfactant) that others have described. The important “foam” is microscopic, and these “bubbles” called micelles, like u/yalloc describes in their comment. The reason this is so important is that oily dirt does not dissolve in water that well. But these micelles encircle the dirt and bond to it very well, and the outer side dissolves in water very well, making it easier to rinse it away. These microscopic micelles do tend to group together making some visible foam, but not all foam is made up of micelles. Regular old bubbles from foaming agents do make it easier for the liquid to cling to the washing surface a little better, and seep into it, instead of dripping away. That’s why you see foaming cleaners for bath tiles and other surfaces.
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