What ingredient in handmade soaps tends to turn the water a light blue?

Question

I have been ordering different handmade soaps and some leave the bath water a light blue color even though the soap color isn't light blue.

Answer 1

Some handmade soaps have extra fat that is not chemically "tied-up" with other ingredients (particularly those advertised as moisturizers) and it is a chemical bonding with hard elements from the water, ie. calcium, magnesuim etc., to form "soap scum". Its dry form is what you see as spotting on glassware. If you use soft water, it will be reduced or distilled water and it will be eliminated.