[editor-surveyor]

Yes, but serious washing requires a strong enough base to break water’s surface tension, and most wood ash is a bit weak in that area.

Anyway, for the wise, preparation.

[JRandomFreeper]

You have never used homemade lye soap if you think it can't break water surface tension.

The wood ash is used to make lye. The lye and the fat are used to make soap.

/johnny