I've never used hydrofluoric acid.
I used to make the one which is sulphuric and nitric acids mixed together. (can't remember the name of it now - orange stuff - I want to call it "royal jelly" - think it had some sort of regal name!).
I made it very carefully, in a fume cupboard, wearing the appropriate protective gear.
(sue, ex-pharmacological research worker)
I'm not going to try throwing matchsticks into any concentrated acids just to find out!