Potassium fluoride,anhydrous
           Potassium fluoride,extra pure
           Potassium fluoride,Granular
           Silicon Dioxide
           Hydrofluoric acid
           Synthetic Cryolite
           Potassium Fluoaluminate
           Ammonium bifluoride
           Potassium Bifluoride
           Aluminium fluoride
           Sodium fluoride
           Potassium Fluorosilicate
           Fluorosilicic Acid
           Sodium silicofluoride
           Potassium Hydroxide Flakes
           Magnesium Fluoride
           Magnesium fluorosilicate
           Barium Fluoride
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What color will be when the skin stained with hydrofluoric acid ?  

Of early skin flushing, and gradually turn dark red, dry, pale wound, necrosis, following to a black or purple black, the formation of blisters containing coffee colored liquid.  

Why my skin is not pain after stained with hydrofluoric acid, but after a long time to pain?  

There is an incubation period of skin of Hydrofluoric acid. The longer of incubation period of injury, as determined and related to the degree of local damage, systemic manifestations and hydrofluoric acid concentration and action time and patient tolerance and other factors.

Reports indicate that death due to hydrofluoric acid exposure is usually the result of inhalation of vapor causing pulmonary edema and fluoride poisoning. Absorption via the skin route of fluoride ion sufficient to cause serious systemic problems and even death has rarely been reported. A fatality resulting from a severe facial burn, which produced acute systemic fluoride poisoning with profound hypocalcemia and hypomagnesemia, is presented. The importance of proper personal protective equipment as well as the immediate initiation of first aid and appropriate medical measures, including the monitoring and replacement of serum calcium and magnesium, are emphasized.

Here is a reviewof  hydrofluoric acid burns: Hydrofluoric acid (HF) is a highly dangerous substance with a wide range of industrial as well as domestic applications. It is unique in both the severity of the cutaneous burns it may produce, and its potential for systemic and occasionally lethal toxicity. The literature on the treatment of HF injuries is extensive, though occasionally confusing and often contradictory, with no coherent management policy emerging. In this paper we present a comprehensive account of the evolution of therapy, drawing on clinical reports and experimental studies.