Though Soaps are coloured , the foams are always colourless!

We use different kinds of  soap , different colour soaps. Yet whenever we wash, we get only colourless foams or lather. Why is that the lather is not coloured?

when soap is mixed with water and lathered, it mixes air and forms bubbles. This we call foam.  These bubbles have more air inside  than the  soap material. Also colour of natural light is white. This reflection of light in soap produces white foams instead of coloured foams. If we use coloured light and see these foams , the foams may appear coloured since they reflect coloured light.
Thus a thin film of bubble has lots of air and because of low surface tension this thin film forms many small  bubbles - large surface area! When light strikes these innumerable bubbles it gets scattered.
So all foams are white in colour.

Which soap is good ? Which soap has highest TFM?

Cleaning action of soap

Soap’s molecules-consist of a hydrophilic (water loving) and a hydrophobic (water fearing) part.

The water molecules alone are unable to pass through a greasy stain, since oil and water do not mix.

Soap molecules, through their hydrophobic side, pass through the dirt, surround it and disrupt it, while their hydrophilic side helps to dissolve it.

Soap attracts the dirt and water washes away the dirty soap.

Which soap is good for bathing?

Soap which has high TFM is good.

TFM is total fatty matter.

i made a short survey of some of the soaps existing in market.

quite interesting!

Several soaps have good TFM value. Greater the TFM, greater is the ability to remove dirt.

Greater the TFM greater is the cleaning ability of soap

Soap                                   TFM value

Mysore sandal                         78%

cinthol                                   79%

fair glow                                   76%

Godrej no.1                             76%

park avenue                             76%

lux creamy white                       72%

dettol skincare                           71%

margo                                        71%

rexona                                        70%

hamam                                        65%

Himalaya soaps                           76%

Yardley                                        78%

Fiama di wils, Dove, pears oil clear,medimix sandal- bathing bars

lifebuoy -45% TFM