Do not machine wash your black-out curtains

I am trying to be a better housekeeper and decided to take a white-colored black-out curtain in a Washer on a gentle cycle. After the washer stopped churning, my beautiful white curtain looked like this—-destroyed.  However gentle, after being churned, the curtains have to be thrown into a trash can. 

Remember: do not machine wash your black-out curtain. The layer that blocks light will be destroyed by the machine even in a gentle cycle.  How to wash it so it can be put back on and continues to protect your dreams?

• Handwash and use gentle detergent
• Spot clean.
• Hand vacuum dusts off the curtains.