Korozní monitoring v rukách restaurátorů a konzervátorů / Corrosion monitoring in the hands of restorers and conservators

A technique for continuous monitoring of atmospheric corrosivitywas developed. An electronic unit measures and recordschanges in the electrical resistance of a thin metal trackapplied on an insulating substrate. If the metal corrodes, theeffective cross-sectional area of the track decreases and theelectrical resistance increases. Sensors made of silver, copper,iron / steel, zinc, lead, tin, bronze and brass at thicknesses from50 nm to 250 μm were tailored for environments with differentcorrosivity. The developed technology proved to provide subÅngström(<10-10 m) sensitivity allowing for real-time corrosionmonitoring even in low-corrosive indoor cultural heritagefacilities. Laboratory tests showed good reproducibility of thetechnique with standard deviation of parallel measurements upto ±20% for metals corroding in a given environment mostlyuniformly. Since the technique measures the maximal depth ofcorrosion attack, the response is somewhat higher comparedto methods measuring the average corrosion depth. Severalexamples from a wide testing programme in partner museums,archives, libraries and other institutions were selected to showsuccessful applications of the technique for qualifi cation andcomparison of air quality control in indoor premises, assessmentof new buildings and storage facilities, air quality controlduring transport and temporary exhibitions and fundamentalstudies of optimal conservation and storage procedures. A fi rstoutline of a classifi cation system for lead, which is particularlysensitive to presence of carboxylic acids, is given. The techniquehas a large potential as an independent method of airquality monitoring in facilities displaying and storing valuableobjects of cultural heritage.