Because leaf pounding is a dyeing process, you need fabric that has been prepared for dyeing. You can use PFD fabric (prepared for dyeing), which is already treated and ready to pound on, or you can treat it yourself. If your fabric has not been prepared for dyeing, the colors will quickly fade.

Use 100-percent cotton in white or any light color. The ingredients used in treating the fabric for dyeing are alum and washing soda. Alum (aluminum sulfate) can be purchased in small quantities in the baking aisle of the grocery store. It can be purchased in larger quantities from an artist's supply store (not a craft store) or ordered directly from the pharmacist.

Washing soda can be purchased in the laundry detergent aisle of any grocery store. Arm & Hammer makes one brand, packaged in a yellow box.

Treating the fabric:

1. Wash fabric in hot water using regular laundry detergent and two tablespoons of washing soda. Run the rinse cycle three to four times to make sure all the washing soda is removed.

2. Remove the fabric from the washing machine and place it in a bucket or large container. Add two cups of hot water and 1/4 cup of alum for each yard of fabric. If needed, add more hot water, but do not add more alum. Stir until alum dissolves. Allow the water to cool. This could take several hours.

3. In a separate cup or bowl, dissolve washing soda (one teaspoon for each yard of muslin) in a small amount of hot water--about 1/2 cup. Add this mixture to the container holding the fabric. At this point it MIGHT fizz.

3. Soak this overnight or for at least eight hours. RINSE. Wring out and line dry. Iron while it is still damp to remove all the wrinkles easily.

---source, HGTV