1) ink for election especially 2)violet color, turn to dark brown after tip on the finger 3)stain on fingers at least 72hour

1)indelible ink  for election especially 2)violet color ,when the ink tipped on the finger ,turn to brown color3)stain on finger al least 72 hours,it can't be washed by water ,and used for election ,the silver nitrate contending can be required by customer,

4) previous experences in elections for Iraq,Tanzania,Afghanistan ,Nigeria,Sudan