Water Hardness and soap suds

[Cheesejawa]

I heard in science yesterday that when you wash your hair with harder water it makes more suds and take longer to rinse them out. Could this possibly be used insted of a test kit?

[davidb]

Wrong way around. It is harder to get soaps and detergents to bubble (forgotten the technical term) if the water is hard. it wouldn't be a very scientific way of testing the water hardness because of course it would be a qualitative verus a quantitative analysis and there will be other variables which can distor the result . easier just to buy a gh testkit methinks

[alanmin4304]

If you boil animal fat and caustic soda you get sodium stearate (soap) and glycerene. If you disolve soap in hard water the sodium goes into solution and the calcium links with the stearate and this is the insoluble scum on the bath. The soap will not lather until the calcium has been used up. The original test for water hardness was a titration of standard soap solution against the sample until the mixture formed bubbles (lather).

Detergents are not affected by water hardness as one end of the molecule is soluble in water and the other in fat. Detergents don't need to froth but they have surfactants added so they do otherwise mother will not buy them.

[Caper]

One of my sister's loves when she comes down this way because of all the suds when she showers...that's how I always remember that the water here is soft!

Caper