Sail Cleaning

My sails are getting a bit dingy and need to be cleaned. What is the best product for this? Can I use a scrub brush, or would that damage the sails?

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Dave

Mine was also looking a bit grubby, just laid it out on the grass, wet it down with a hose and used a fairly soft scrubbing brush with a mild household dishwashing detergent. Hands and knees scrub until clean, flip over and repeat, hose off, dry and put away.