Hydrofluoric acid is an uncommon chemical, and with reason. But it is used in the semiconductor industry, for etching glass, in alpha spectroscopy sample preparation, and other cases.

Even dilute solutions of HF can cause serious chemical burns. Local effects include tissue destruction and necrosis, as with any acid, but free fluorine ions cause bone destruction, hyperkalemia, hypocalcemia, hypomagnesemia, and sudden death. Deaths have been reported from concentrated acid burns to as little as 2.5% of body surface area.

Dilute solutions may not cause any symptoms for some time, until they have diffused through the body and been absorbed. This makes the effects essentially impossible to treat. The fluorine ions also stimulate pain nerves and the sensation is said to be excruciating

Damage to bones and nails is likely to be permanent, and permanent nervous system damage may also occur (presuming you live long enough for this to matter, which may be unlikely).

Immediate treatment with calcium gluconate gel will substantially improve the prognosis. It is vitally important that all facilities handling HF keep adequate supplies on hand.