1. Fill your bathtub half full with lukewarm to cool water, adding a quarter of a cup of liquid detergent to the water. Lower the curtain into the water until it is fully submersed.
2. Push the curtain down into the water with your hands along different areas to force the detergent suds into the curtain evenly while providing light agitation. Five minutes of gentle pushing should be sufficient.
3. Drain the soapy water and refill the tub with clean lukewarm to cool water. Rinse the material using the same pushing method as you did for washing. Drain the rinse water. Squeeze the fabric to remove excess water, but do not wring or twist.
4. Hang the curtain along a clothesline outdoors or in your home to drip dry until it is mostly damp.
5. Spread the damp curtain with the front side of the fabric facing down over your ironing board. Place a thin towel over one area at a time and iron over the towel with a moderately warm iron. Move the towel and continue to press the curtain until it is fully dried.