I just did this project a few months ago at one of the schools I work at. The 5th and 6th graders are studying the early explorers thru the 1800's for history this year so I have been looking for projects relating to that time period. My husband had the great idea to use tea for paint and do a drawing of the actual Boston Tea Party. I handed out copies of a drawing and they used that as a guide for their own painting.
extra fine line Sharpie
The first step to this project was creating the tea "paint". I made the tea in a pan with two cups of water and about 6 tea bags and cooked it down to about a 1 cup concentrate. I used cranberry raspberry herb tea (which brews red, but turns grey on the paper), and english breakfast black tea (which brews a dark brown, but turns tan on the paper). You could try any tea and see what you come up with. I was looking for two distinct different colors so these teas did the trick.
After they practiced sketching the scene, they went over all the lines with a Sharpie, then "painted" it in with the tea. They only had the two color choices, so they had to make some decisions on how to make the picture look the most interesting. If they did more than one layer they could darken the color, so I told them to just experiement with it. I love the old world look it gave the paintings, which seemed fitting for the subject matter.
This was kind of a quick painting project so I had them do either a two or three teacup drawing as well to use the tea on. Those turned out great too!