Testing of a new wax coating Poligen ES 91009® and corrosion inhibitor additives used for improving coatings for historic iron alloys

Abstract

Research into commercially available Poligen ES 91009® wax coating and corrosion inhibitor (CI) additives for improving protection coatings are tested using a systematic methodology on iron coupons. The testing involves accelerated aging of coated and uncoated coupons in a climatic chamber, electrochemical measurements using (polarization resistance (Rp) and electrochemical impedance spectroscopy (EIS)) in different electrolyte solutions, along with long-term aging of coupons at the Criminology Museum in Greece and the Palace Armoury collection in Malta. Both museums were selected for their uncontrolled environmental conditions and housing of historical iron collections. The electrochemical measurements found Poligen® to be a superior coating when compared to 15% (w/v) Paraloid® B-72 in acetone, but the addition of CI additives did not improve their protective properties. The accelerated aging of the coupons confirmed the electrochemical measurements, but for the long-term testing, after 3 to 7 months of exposure in the museums it is still too soon to rate the coatings.