How do you whiten polyester white lace curtains?

Give them a vinegar soak with some baking soda tossed in. If you use bleach it might turn them either yellow or a yucky gray color.

You can also hang them outside in bright sunshine after washing them, and it might help whiten them up a bit as well.

Use hydrogen peroxide mixed with your laundry soap.

Try soaking/washing in Oxyclean.

hang in evening due / bought a crochet bedspread at yard sale / dog was using for blanket / washed it / spread it out on grass (back yard had fence) in evening due and it bleached it - my grandmother told me this trick

Soak it in denture cleaner!