Wow, ALot of great info hear..While I think eventuall making my own soap as another step towards independent living might be a great skill to learn I was interested in finding out if you could use wood ash and water to effectively perform moderate dish cleaning and hygenic duties while in the field.
Riley?
Try it at home.
First soap I made came from Draino-type drain cleaner product (read label to make sure it is a lye formulation) and saved, rendered bacon fat, wooden spoon, and water. Tedious, but neat to have done.
You can add fragrances, but it is not necessary. I'd also be careful about using it, it is NOT the commercial soap you wash your lovely complexion with each night.

Your formulation can make a difference. Test before using near sensitive areas.
Used lamb fat a neighbor gave me once. I was better and the soap turned out well, but took a while to reduce the lamb fat to oil. Had a (duh) lamb-meat scent.
STILL have some saved venison fat
(it has been years now...jeez, I gotta do something about that stuff
) I know I used it once, but don't remember the final product differences. Venison fat coagulates much quicker than beef, pork, or lamb fat, and seems much denser than the others...to me, at least.
Read cautionary elements of instructions, please. Think aluminum pots are out. KNOW that you add the lye, rather than adding TO the lye, because of splattering potential of caustic solution. Simple stuff, but important.
Not that difficult, somewhat tedious, kinda neat to make your own.
Be safe, have fun.
Kis
enjoy every sandwich