Copper Sulfate Crystals, 1 lb. 3 oz. Bottle, by Tinker & Rasor

Copper sulfate crystals are used to recharge portable, copper-copper sulfate reference electrodes used in the cathodic protection testing.  Simply mix the copper sulfate crystals with distilled water to recharge the electrode.  At the same time, it is a good time to clean the internal copper rod with an abrasive product such as sand paper or a scouring pad but do not use emery cloth as this introduces metal onto the copper rod. 
 

Active Ingredients