Cotton should be treated with care and here are some care instructions.
Use luke warm water containing a white or clear, high grade dish soap. Wet, carefully and then massage the soap into the cotton rope gently using your hand.(Important: If you rub or scrub a cotton it will pull the cotton fibers out) Rinse in clean cool water. Repeat if necessary until cotton is clean. Rinse again to remove all the soap. Then leave out to dry.
If some stains remain then Carefully dab with a mild bleach solution and rinse immediately!
Only store your cotton once it is completely dry and store it in a “cool and dry” location. Ensure any covering you use to store the cotton can breath to avoid possible mildew. Do not store in plastic for any length of time.