Study on the restoration of glass slides dating back to the 1940s

The Museum of Sun Yat-sen University houses a collection of antique glass slides dating back to the 1940s. These historical artifacts not only serve as a record of the past but also bring history to life. During extended storage, the emulsion layer on glass slides may harden and become brittle, leading to cracking and buckling. This study suggests a method to enhance the physical property of the emulsion layer by using a combination of nonionic surfactant isomeric alcohol ethoxylates eight (TO-8) and waterborne epoxy resin (WER). We investigated the microscopic action mechanism of the two on the emulsion layer of glass slides using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), water contact angles, and other techniques. Our study revealed that TO-8 can significantly eliminate the spherulitic crystal structure of the emulsion layer, as well as improve its softness and hydrophilicity. The addition of the WER ensures that the cracking and warping of the emulsion layer film is fully corrected, resulting in a flat surface. Additionally, the size of the emulsion layer film remains stable even after wetting. The WER has minimal impact on the image information of glass slides. The emulsion layer of the glass slides, restored using the softening protection solutions developed in this study, showed almost full recovery of image information. This research holds significant theoretical and practical value for repairing cracked and warped emulsion layers on glass slides.