Building lather start-to-finish on the soap tends to make for a more soap-rich lather. This is all well and good, if that's what you're after, but there are two points to remember:

  • some soaps need relatively more water than others to lather well, which can be tough if you're scrubbing off more and more soap while you're adding water;


  • allergies/sensitivities that you might not otherwise encounter can crop up if the lather is very soap-rich.