染 nine deeps into a liquid from a tree, it contain a 九, it is a gradual process.
染 related to liquid, 熏 related to smoke. Water and fire are the medium. These would not meet Mao's taste, who needs 烧, faster, nine thousands years are too long, a fire is a day's job.
染 there we were from two different dye, red and black. They are not simply banana.