A pack of Ferric Chloride Fe Cl 3 crystals for etching copper clad boards. Packet contains sufficient crystals to make one pint of solution. Dissolve in 250ml of warm water. Store & etch in plastic or glass vessels. With regular stirring etching will take about 20 minutes or longer depending on how many times solution has been used before. One pint will etch about 2260sq.cm. 350sq.in..