I have some peachy cotton interlock for dolls, but I'd like a darker color. Can I overdye it with tea? If so, how? Or, is there something else I should use instead of tea?

not sure if tea is permanent...does it fade over time?

a weak solution of "Dark Brown" RIT dye would work well. I use tan, peach, or dk brown...either alone or mixed in various concentrations to dye doll skin since I can get a better price on white interlock and more variety of skin tones that way.

If you do dye with rit know that it will look much darker when wet...and will fade some when washed after dyeing. I always wash after to remove any residue.