I have used a product called "Magic Batik" for hot dye baths...so it would
work for hot tea, too. This product comes in convenient squeeze bottles. It
goes on as a liquid and stiffens up in the hot dye. After you are finished
dying the cloth, the Magic Batik washes out with cold water. I am planning
to use it for "mud cloth" like designs (I hope it is still available?)