On 8/3/2017 12:29 PM, Doug Miller wrote:
Muggles wrote in newslvhi0$iam$1
@wxy247t1uve70-5cv.eternal-september.org:

I know there's some sort of process going on when soap foams and bubbles
up whether or not it's bath soap or dish soap, and I always thought the
foam in the soap is what broke down the dirt and oils.


Nope. It's the soap in the water that breaks down oils and helps dissolve or suspend dirt.

http://www.explainthatstuff.com/detergents.html

Foam forms when soapy water is agitated because the surface tension of soapy water is
much lower than that of pure water, that's all.

If it were the foam doing the cleaning, how would a clothes washer ever get your clothing
clean? The foam is all on top of the water, and the clothing is under the water.

OK Thanks for the link!

The one thing I haven't seen a specific answer to is why does bath oil
prevent soap from foaming up?

For example, when I put the liquid bath soap onto a bath puff, it
usually will foam up when I add water to it.

If add some bath oil to the water first, and then try to use water with
bath oil in it to foam up the soap filled bath puff, it's like the bath
soap doesn't do anything - doesn't foam up, and is useless to wash with.

I understand what has been mentioned thus far in the explanations about
the molecules and emulsions.

Does oil prevent soap from foaming up because the reaction between the
two is instantaneous and soap becomes an emulsion on contact with oil,
therefore, no longer actually being soap?


Detergents like
Dawn seem to be able to still foam up even when oils are present,
though. Maybe, it's more than just soap like what bath soaps are that
don't foam up if oil is in the water?

I wonder how they can make bath soap products foam up when they say they
contain oils to moisturize the skin? I've noticed after using bath oil
on my skin that subsequent baths that I take the foaming bath soap still
doesn't want to lather up because of the oil/moisturizer that is still
in my skin.

Anyway, I'm more curious about the chemical process going on, and if
there were a way to keep the foaming bath soap foaming even if bath oil
were present.




--
Maggie