An infrared and SEM study of the margins of some german hyperinflation postage stamps

Abstract

Infrared spectroscopy and scanning electron microscopy (SEM) studies were performed on the margins (the area without printed colors) of a set of German postage stamps dated 1923 and corresponding to the hyperinflationary period of economy. SEM results showed the presence of Al, Si, Zn and S in the samples, but in different combinations. Sulfur is considered to be a contaminant. The Al-Si combination is credited to kaolinite, Zn to ZnO and unaccompanied Al possibly to Al2O3. Several experimental IR bands of kaolinite agree with the suggestion of its existence in some stamps. In the case of Al and Zn alone we have supposed that, with the passing of time and with the help of moisture, AlOH and ZnOH were formed in a quantity allowing detecting some of the metal- OH bands by IR spectroscopy. On the basis of previous infrared experimental results on Al and Zn hydroxides we assigned some IR bands to the OH groups bonded to these metals. Our results indicate that it is highly probable that the paper used to print these postage stamps was originated in more than one paper mill.