Twist the wool and then tie it into a loose knot. Wash and rinse the wool using the soap flakes. Mix the alum, cream of tartar and just enough water for the alum and cream of tartar to dissolve in it.
Pour the remaining water into a saucepan. Add in the mixture of tartar and alum that you made. Place the newly washed wool into the water-filled saucepan and boil the wool in the water for an hour on low heat. Stir it intermittently while boiling.
Take the wool out without squeezing out the water and store it inside a plastic bag until you have prepared the dye bath.
Prepare the dye bath. To do this, you will need to crush the lichen and add it to the saucepan filled with water.
Take the wool out of the plastic bag and put it into the saucepan with the water and lichen.
Simmer the lichen and wool until the wool turns the color that you want it to be. Lichen can produce a range of colors varying from green to light orange.
Use the tongs to remove the skein of wool from the dye bath. Place the wool on a clothesline so that it can dry.