Rhubarb leaves contain oxalic acid, a poisonous substance, but it can be used as a mordant. Difficulty Level: Average Time Required: 4 hours

Here's How: Wear rubber gloves and protective clothing. Cut rhubarb leaves into small pieces and place in a large dyepot filled with water. Simmer for 2 hours, covered. Avoid vapor inhalation. Strain the mordant liquid, removing the leaves. Place clean, wet wool into the rhubarb mordant liquid and simmer 1 - 2 hours. Allow the mordant to cool before removing the wool.

Tips: Rhubarb leaves contain oxalic acid which is toxic. Store covered and keep away from small children or pets. Rhubarb roots can produce shades of orange and reds. Rhubarb stalks make wonderful pies.