Ash stains on an outdoor sofa can be stubborn, but with the right approach, they can be removed effectively. Start by brushing off loose ash with a soft-bristle brush to avoid spreading the stain. Mix a solution of mild dish soap and warm water, then gently scrub the stained area using a sponge or soft cloth. For tougher stains, a paste of baking soda and water can be applied, left for 10-15 minutes, and then rinsed off. Avoid harsh chemicals that may damage the fabric or material. Regular maintenance, such as covering the sofa when not in use, can prevent future stains. Always test any cleaning solution on a small, hidden area first to ensure it doesn’t cause discoloration.