Hydroflouric acid is used in it's 30% state mixed with concentrated sulphuric acid for the polishing of lead crystal after cutting.
The cut crystal is literally rubbed by hand in baths of the above with heavy duty rubber gloves the only protection.
Operators are invariably splashed but I know of none who have suffered losing limbs or de-calcified bones.
Hydroflouric acid is also used mixed with ferric chloride as a pickle for heat treated stainless steel again operators get splashed , this is inevitable in an industrial enviroment but again I know of no-one who has suffered what we are lead to believe can happen from burning a small amount of PTFE.
I use Viton o'rings in my steam engines , they carry no hazard , I am unlikely to set fire to them and savour the smoke.
I machine PTFE and again there is no hazard, use very sharp tools and the "swarf" will be in one long piece , very easy to place in your dustbin , it does not get hot during machining.
Don't be frightened by such claims and warnings , by the very nature of what we do workbenches and hands will inevitably be contaminated , do the obvious and you will come to no harm.
It is not good to smoke - period , it is less good to smoke whilst working !
If making dust wear a mask , wear eye protection where applicable and wash hands before eating or smoking.
When it comes to machining alloys containing Beryllium or Cadmium well that's a different story.
