I took time out today to browse through the old shophouses near my place and to my surprise, found a pack of laundry blue. 50 years ago, dhobys' (Indian Laundry) used this to whiten clothes. It stains clothes a slight blue but drys out into a crisp white. Laundry blue is no longer sold to the masses as modern cleaning products have incorporated the same properties into their laundry soap. So I am going to try it out at home.