Restoration and conservation of the archaeological Islamic sandstone tombstones applied on a tombstone from the second Abbasid era in Egypt

The stone Islamic tombstones are one of the most important sources of dating, with their inscriptions in various Arabic calligraphies. This research aims to study Islamic sandstone tombstones with an application to a tombstone from the second Abbasid era in the Islamic history which is dated through the inscriptions on its surface and written in simple Kufic calligraphy, where this tombstone dates back to 272 AH and bears the name of its owner Ibrahim bin Suhaib. Sandstone samples from the tombstone were studied and examined by stereomicroscope, scanning electron microscope (SEM) and analyzed by X-ray diffraction (XRD) and elemental analysis by the EDX unit, It was found through examination by microscopes that there is a weakness in the sandstone, it was noted through the analysis by X-ray diffraction that the main compound is silicon dioxide (SiO₂), and the presence of iron compounds was not clearly shown. As for the elemental analysis by EDX, it showed the presence of iron oxides within the sandstone components, which are highly susceptible to the presence of moisture and may have a partial dissolution. The restoration works were carried out for the tombstone, which bears No. 117 in the museumstore's register (Seven rooms museumstore – Al Fustat) , where the mechanical cleaning of the thick layers of dirt was carried out, as well as the chemical cleaning processes with a solution of ethyl alcohol and water to remove the mud stains ,consolidation processes were also carried out for the deteriorated sandstone by Wacker (OH) 100 at a concentration of 3%, and the final isolation was done by the same material, but with a concentration of 10%, with the aim of restoring and preserving it.