Clean and Pink has been using this tool, strategically for a decade. This tool has been around for over 75 years. Read about it, its abrasive and can only be used on certain things. Demo small areas before using and wear gloves. The pumice rock is abrasive. I use on toilets and rust areas in bathrooms. Experienced cleaning companies such as Clean and Pink has trained staff on how to use the rock and on what surfaces. An interesting source is Geology.com, see article by Dr. Hobart M. King, Dr.,RPG. Remember, if you live in Memphis, Clean and Pink will clean it for you.