Why does a white cake of soap go dark?

  • 1 Replies
  • 2615 Views

0 Members and 1 Guest are viewing this topic.

*

Offline chris

  • Neilep Level Member
  • ******
  • 5424
  • The Naked Scientist
    • View Profile
    • The Naked Scientists
Why does a white cake of soap go dark?
« on: 14/08/2011 17:22:54 »
I've noticed that white cakes of soap often darken with age, developing grey patches / lines of discolouration.

My own feeling is that this is where water has penetrated inside the soap, disrupting the crystal structure and therefore making it less reflective, so parts look dark. What do people think?
I never forget a face, but in your case I'll make an exception - Groucho Marx

*

Offline Geezer

  • Neilep Level Member
  • ******
  • 8328
  • "Vive la rÚsistance!"
    • View Profile
Why does a white cake of soap go dark?
« Reply #1 on: 15/08/2011 07:25:50 »
I always thought those nasty black lines that form in the "crevasses" in the soap were some sort of alien lifeform that had emerged from all the muck on the soap, so I usually throw the bar of soap in the bin when that happens.

There ain'ta no sanity clause, and there ain'ta no centrifugal force Šther.