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.