1. Fill the bathtub with warm water.
2. Pour in neutral detergent.
3. Soak the cushion in the water and gently rub it.
4. Remove and rinse thoroughly with hot water.
5. Squeeze out the water with a large towel.
6. Reshape the cushion to its original shape.
7. Dry it in direct sunlight on a sunny day.
8. Comb the fabric again to smooth it out.
