Home Home Decor Tub Cleaner: Vinegar And Dish Soap, No Scrubbing. Heat 1/2 Cups White Vinegar In Microwave For 90 Seconds, Pour Into Spray Bottle. Add 1/2 Cups Blue Dawn Dish Soap. Shake Gently To Mix. Spray On Surface, Let It Sit 1-2 Hours. Just Wipe It Away, Then Rinse With Water. Should Also Take Soap Scum Off Shower Doors.