"George Patterson" wrote in message news:Qib_h.6492$2V1.4453@trnddc08...
Pszemol wrote:

Advice your mom to use muriatic acid (HCl) to wash of this white residue

I see the smilie. Are you serious?

It will react with calcium in this white residue and chemical reaction
will form calcium chloride, which is water-soluble and it will be easy
to wash it from the wall with a garden hose...
Use small quantities and wear protection clothes and safety glasses.