Dry plate glass negatives are important part of the cultural, historical and visual heritage in history of Iran. Structural changes due to factors affected them over time, can cause deterioration in the image. Identifying deteriorations in dry plate glass negatives can help to provide better solutions in preserving them. The investigation of sample by Fourier transform infrared spectroscopy (FTIR) and x-ray microprobe analyzer (XPMA) indicated that the technique of sample is gelatin and silver halide on glass, and the chemical damages are fading and silver mirroring. Improper washing after fixing and residual of hypo on the surface of image is the main cause of fading. The formation of the silver mirroring is due to the oxidation of silver ions in the emulsion layer and migrate to the surface of the negative.
Wood is an organic material which has been used for manufacturing of different historic relics. There are many historic wooden relics in open air spaces under effect of environmental factors. Weathering and its photochemical decay is one of the most important degradation factors of these relics in dry and semi dry climates. Therefore, it is necessary to study different procedures for conservation of these relics. Nano Zinc Oxide characteristics were studied as a conservation treatment for wood against photochemical weathering. Samples were prepared from White Poplar (Populus alba L.) as a widely used wood in historic relics of Iran. Specimens were treated with Nano Zinc Oxide suspension in isopropanol by surface treatment. Specimens were artificially weathered regarding to ASTM 2565-99 in 300, 800 and 2000 hours as three time levels. Samples were analyzed by evaluation of mass loss, pH measurement, Colorimeter, and ATR-FTIR spectroscopy. Results showed that the treatment does not prevent aesthetical change of wood appearance in weathering process although the alteration was not severe. The treatment reduces weathering effects but does not prevent its structural degradation. During the time and under effect of weathering, Zinc Oxide nanoparticles will lose their function as ultraviolet absorbent due to chemical reactions with wood structures and first degradation products. Therefore, its efficiency won’t be enough in long term period.
