Ferrous Chloride (FeCl2) solution is used to etching Copper from Copper Clad to make the PCB. Ferrous Chloride (FeCI2) which is corrosive and one should avoid skin and eye contact. Use of glasses, gloves and protective overalls are strongly recommended. If you do get any on your skin then wash it off immediately with water and soap. Seek medical attention in abnormal situations.