首页|The chemistry behind the first Portuguese postage stamps(1853-1894).A non-destructive analytical and chemometric analysis of pigments,fillers and binders
The chemistry behind the first Portuguese postage stamps(1853-1894).A non-destructive analytical and chemometric analysis of pigments,fillers and binders
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NSTL
The analysis of 28 specimens of some of the first Portuguese postage stamps,dated from 1853 to 1894,undertaken with non-destructive techniques:X-Ray fluorescence(XRF),Attenuated Total Reflection Fou Transform Infrared(ATR-FTIR)and Ultraviolet-Visible Reflectance Spectroscopy(UV-Vis).Ink,paper cancellation of the postage stamps were analysed,and the pigments,binders and fillers identified.Prussian 1 was found present in all blue and also in green and brown specimens.Chrome and zinc yellow,lead sulphate mars red were also found in other of the investigated postage stamps.Binders consist mostly of protein g Fillers such as calcite and kaolinite were found dominant.The presence of the latter served as an indicator distinguishing between genuine and forged samples.UV-Vis spectra also proved useful for the same purpose,the above information was processed and organized using chemometric techniques.These include mainly erarchical Cluster Analysis(HCA),for clustering stamps of similar composition,and Principal Compor Analysis(PCA)for mapping the samples and identifying the more relevant variables.The latter are,in the pa content of calcium,potassium,sulphur and silicon and,in the dye pigment area,of iron,zinc and lead cont The study introduces an approach in which,by combination of non-destructive multi analytical techniques v chemometric analysis,extensive information on different aspects of the composition of the studied post stamps is provided,including that of paper and dyes.
NSTL
