At the end of 2007, we were asked, by the Social Fund, to restore the mosque of Al Ashrafiya in Ta’izz erected in the fifteenth century AD.
The paintings basis was realizzed with a lime and various kind of aggregates plaster, applied on a brick masonry and mortar support with mortar. The stratigraphic sequences of the plaster is not possible to distinguish because of the local traditional technique of mural painting called qadad.
This technique involves the application of a layer of plaster with a particle size of coarse aggregates, repeatedly beaten with a stone cutting. The subsequent drafting of the plaster, compose by a more thin aggregate, is constantly beat. This process causes the penetration of the plaster’s components, so the it is presented as a single layer extremely hard and solid, further refined and smoothed with a flat stone to polish the surface.
Preservation status
The degradation causes can be attributed to a number of factors. The combined action of these following phenomenon had greatly exacerbated it:
I.I seismic movements
II. Geological instability
III. The rainwater from the roof associated to physical, but mostly chemical, damages
IV. anthropogenic degradation
After a carefull observation of the conservation status of the mosque, was initiated a work of restoration, wich includes the consolidation of the walls, and the restoration of the wall paintings.
Intervention
The first operation performed was the consolidation of the plaster and its readhesion to the wall structure. To recreate the cohesion failed with the degradation of the material, we have made injections of a specific desalinated fluid mortar filling the voids and anchoring the plaster layer to the support.
The chemical cleaning method to remove superficial dirt requested specific measurment. Were therefore used solutions of ammonium carbonate in demineralized water in some cases adding EDTA. Where the methods mentioned above have not given satisfactory results, the cleaning was taken up in a selective way with AB57, ion exchange resins and mechanical action with steel scalpel and / or glass fiber pens.
The pictural retouchs was preceded by a series of preliminary tests aimed at defining the technical and the mix best suited to fill the cracks and restore it into surface continuity.
Then, began the reintegration of the pictural parts and Koranic inscriptions. The water-colors used are of the highest quality and perfectly reversible.
The reintegration of the many gaps of the gypsum ornaments was a very delicate stage of work and required specialized Yemeni craftsmen skills.