Fill the sink or bucket with cool or lukewarm water. Do not use hot water or the chiffon may shrink.
Add a capful of mild hand-washing detergent to the water and use your hand to mix the detergent well.
Place the fabric into the water and allow it to soak for a few minutes.
Stir the fabric in the soapy water to clean it thoroughly. You may also scrub the garment against a washboard.
Empty the sink or bucket and refill with it with cold water.
Swirl the garment around in the water to remove the detergent. You may have to do this a few times to thoroughly remove all traces of the detergent.
Squeeze as much water from the garment as possible and arrange it on a flat dry surface. Allow the fabric to air dry.