Have been thinking of tea staining as well, for a similar old quilt repair problem that I have.
Though I haven't jumped into it as I have huge hesitations.
Does tea stained fabric hold it's colour? Or how do you stabilize it?
Or is it just for show, and you should not plan to wash the fabric, as you will wash the staining out?
How do you do your tea staining?
Likewise, if coffee staining, is it all the same re the process? as well as the permanency, or lack of?
THANKS!