How do you wash a white hat without ruining it?

Question:I got a dirt and stains on my white hat and i was wondering how you would be able to wash it without putting it in the washing machine and would hot/warm water work better or cold water for washing. Its polyester too thanks

Answers:
First soak your hat in cold water, Remove from the water. Now rub with Natural Soap. Leave the soap on and free from water for 1/2 hr. This lets the soap do it´s work. Now back to the water, give a little rub, rinse well. Now hang your hat outside in the sun. The sun will do the rest of the work for you , by bleaching out any remaining stains, the natural way. Your hat will then be whiter than white