There are tools that take a liquid product (e.g. soap) & spray it as a foam (some of these tools use a hand-pumping action, while others use a pressure washer, or even a stream of water.)
How do these products do this (turn the liquid into a foam)? I imagine it has something to do w/ pressure & maybe viscosity, since I don’t think water can be foamed?
If there’s a difference b/w the different versions (hand vs electric. etc), I’m okay with only explaining the hand version.
Also, possibly worth noting is that I don’t really know what the difference between foam and a liquid is, so perhaps this question is equivalent to “what is foam”.
My best guess, it must be some way that it takes air from the outside (when you press down on the handle) and forces the air as many little bubbles into the liquid. The handles probably consist of a double tube for this purpose.
How does this happen though? Putting air & a liquid in a bottle together doesn’t make them mix. Is it through increasing the pressure in the container (by adding more air?), or maybe they have a sieve or special valve or something.
