Practical Uses for Ash (preferably in the ancient world)

been doing some research in what uses there are for wood and volcanic ash and so far have found it's been used as fertilizer, insect repellent, soap, part of a cement mixture and for treating iced over roads. Does anyone else know of any other uses for ash?

Ok, not ancient but in medieval times wood ash was used for producing forest glas as well.

It was also used in tanning and dyeing processes.