Hydroflouric acid sprays (HF) are also used in many touchless car washes in varying concentrations across the USA. HF does a great job during the pre-soak phase for cleaning painted surface and especially wheels & glass, but it's every bit as dangerous as already mentioned. It's concentration and dwell times are what makes it more or less friendly, but definitely take precautions if you're going to use it no matter how much you dilute it.
If your skin comes into contact with HF, you won't initially feel any pain or burning sensations because of the fluorine's numbing effect, but it's going through your skin and searching for calcium (i.e. your bones). Several hours after coming in contact with HF, you'll notice that the soft tissues and bones in those areas (typically your hands) are being eaten away from this. It only takes a burn from HF that covers about 2% of your body to kill you and you may not know it's a problem until its too late. Breathe in just a small amount of a 50/50 HF/H2O solution and you could die....seriously!
At full strength this stuff will etch glass and it also loves to eat concrete in addition to your bones, soft tissues, etc. At the right dilutions, it can remove acid rain etchings from glass and leaves it perfectly streak free., but I'd rather spend the extra time polishing glass with a slurry of cerium oxide than further risk my health from using HF. It has its place in the industry, but this is one product I'd advise staying away from for the sake of your health if you don't have any training and or equipment to safely use it.
