Here is the still-wet result of underwear dying using tea. The underwear (and a dress) sat overnight. They are a bit tan-ish, rather than brown. You can also see the 100 black tea bags that did the dying.
And here is the dried underwear. It’s a very light tan.
This was a good $1.82 experiment. That was the cost of the tea. I’ve now purchased some actual brown dye. More to come.