Conservation around the Millennium (Hungarian National Museum, 2001)
Pages - 138
procedure was carried out for two hours while testing equipment was taking samples continuously 10 cm far from the book being worked on from equal distances from the door and ventilation opening. With the first sample method (without the extractor fan and ventilation) the worst circumstances were modelled as if the restorer was working in a small, not ventilated room. DEMONSTRATING ETHYLENE OXIDE CONTENT AND MEASURING ITS CONCENTRATION Air samples were absorbed in 40% sulphuric acid. Sulphuric acid turned the absorbed ethylene oxide into ethylene glycol, which is oxidised into aldehyde with iodate. The aldehyde group added to a chromotropic acid has a colour reaction. Measuring the colour intensity with a spectrophotometric method the results will be in proportion to the ethylene oxide concentration. Results of the Examinations Examined Work Procedure Ethylene Oxide Concentration (mg/mJ) Dry cleaning 1. (dusting off the sheets) Without fan 0.21 With fan 0.08 Wet cleaning (washing the sheets in lukewarm water) Without fan 0.05 With fan 0.07 Drying, ironing (subjecting the sheets to heat) Without fan 0.05 With fan 0.08 Dry cleaning 2. Without fan 0.14 Samples taken outside the cabin 0.08 When evaluating the results of examination on ethylene-oxide, as a carcinogenic matter it is neither the average concentration nor the top concentration which are used, but rather the value of maximum concentration (MC) has to be regarded, which according to the 1988 Hungarian standards is 1 k (mg/m3). “K” means the carcinogenic effect of the element. As in the case of such matters the value limit may not be exceeded for even a short time period there is no point in calculating an average concentration over an 8-hour work period. So in this case the results gained from processing the samples taken during the 2-hour period were compared with the value limits. Results showed that in case of the samples taken in extremely bad circumstances (small chemist cabin, without ventilation while dusting continuously) the measured concentration, not even taking background contamination into consideration, was way under the allowed limit. In case of the first book the value was one fifth of the value limit and in case of the third book ethylene oxide concentration was one seventh of the allowed value. Ethylene oxide concentration in the air samples taken during the other work procedures was around the value of background contamination (it did not exceed that value). 138
