Has been used as a verb since the mid 1600's..."Ash" is now a verb? What the hell has happened to the English language?
ash, v.² meanings, etymology and more | Oxford English Dictionary
ash, v.² meanings, etymology, pronunciation and more in the Oxford English Dictionary
www.oed.com
The earliest known use of the verb ash is in the mid 1600s.
OED's earliest evidence for ash is from 1655, in the writing of James Howell, historian and political writer.
It is also recorded as a noun from the Old English period (pre-1150).