m. mohammadi achachluei

Decorating Iran's historical monuments often involves painting on wood, an area relatively underexplored in research. Examining the color palette utilized by artists in these works can offer valuable insights into the era's commercial, cultural, and economic milieu, while also aiding in identifying deterioration processes and proposing conservation strategies. This study seeks to determine the pigments employed in the paintings on wooden panels of the Shahsavaran House, a structure dating back to the Qajar period in Isfahan city. Utilizing micro-Raman spectroscopy and micro-XRF spectroscopy, the pigment composition of white, green, blue, yellow, and red hues was analyzed. The findings revealed a preliminary layer of white lead applied to the wood surface, followed by the painting execution. Examination of the pigments unveiled the presence of white lead, red lead, chrome yellow, and ultramarine blue. Notably, the green pigment was identified as conichalcite, a pigment not commonly utilized, likely arising from the degradation of emerald green. Furthermore, the presence of massicot alongside white lead in white areas suggests the degradation of white lead in an outdoor environment. The identified pigments in this artwork include lead white, lead red, and ultramarine blue, which are traditional and commonly used pigments in Iranian art-historical works. However, through the identification of chrome yellow and the potential use of emerald green, it is estimated that the paintings can be dated from the mid-19th to the mid-20th century.

Paper turns yellow over time. Bleaching with oxidizing agents is one of the most common methods, which creates a colorless result by breaking down the light-absorbing chromophores. In this research, the changes in the properties of paper by applying oxidizing agents are studied. The paper samples were characterized by colorimetric, infrared spectroscopy, tensile, acidity, and SEM microscopes. Four oxidizing solutions were deployed for whitening the samples of Whatman paper using the Immersion method, including Hydrogen Peroxide (2 % V/V), Sodium Peroxide (2 % W/V), Potassium Periodate (2 % W/V), and Potassium Persulphate (2 % W/V) all solved in distilled water. The samples were treated within 48 hours, and characterizing tests were deployed. The results show that hydrogen peroxide with the highest tensile strength (17.75 Nm/g) and the lowest color difference (∆E= 1.48) after accelerated aging has the best performance among other samples. Also, hydrogen peroxide can be improved tensile strength, increase brightness, reduce yellowing, cause fibers stability, and keep the paper at an almost neutral acidity.

Various destructive factors gradually degrade paper due to its structural properties. For this reason, it is necessary to apply consolidation treatments for strengthening the degraded papers. In this study, cellulose nanofibers with a concentrate of 1% by weight were prepared as a suspension with water to consolidate the paper, then used to treat the samples. The samples were exposed to dry-heat and moist-heat aging to evaluate the treatment effects. pH measuring, colorimetric, and tensile strength tests were performed before and after aging. The results showed that the pH of the cellulose nanofibers treated samples increased. After dry-heat and moist-heat aging, the pH of the samples decreased slightly. Cellulose nanofiber treatment increased the tensile strength of the samples. However, after two stages of aging, the tensile strength of the samples has reduced compared to the previous stage. The application of cellulose nanofiber treatment made the color of the samples brighter, but after aging, the brightness of the samples decreased.