I've used it for years. When I worked in a nursing home years ago, we had to wear all white. My supervisors cloths were always beautifully white and pressed. One day she came in and her pretty white just looked a little blue? So of course I had to ask because I'm not shy. And she told me about this blue stuff. But she also told me if your not careful and let your daughter do your laundry that you could end up blue! It works great.