Teach Soap

I'm not a chemist, so I can't tell you much beyond what is at those links, but we may be looking at a few variables: dry lye vs diluted lye vs raw soap (diluted lye + oils at some point in the saponification process). You can also include rinsing with vinegar before rinsing with water and vice versa.

It may very well be that copious amounts of water is best for dry lye, but vinegar can work for diluted lye and raw soap. But even for those two things, variables (esp strength of the lye solution) come into play.

If I'm remembering my basic chemistry correctly, a weak acid neutralizes a weak base. In a soaper's case, the weak acid is vinegar and the weak base is the lye solution or raw soap. Although I'm pretty sure even a "standard" lye solution (roughly 6oz of water per pound of oils) will be stronger than the 5% acetic acid in vinegar.