Mosaic Conservation and Restoration

Mosaics constitute a shared cultural inheritance from the Roman and Byzantine world throughout the Mediterranean region. Due to the vast number of mosaics presently at risk, there is an urgency to determine common problems,  to promote efforts to better conserve these important historic documents and artistic creations of the past.Mosaic conservation is a practice as old as the making of mosaics themselves. Today one can still find ancient mosaics with patches that were made as part of maintenance when the floors were still in use. In more recent centuries, restoration has been widely practiced on objects of antiquity, including mosaics. And from the first decades of the twentieth century, we have fine examples of restorations. The use of lime-based mortars has allowed the development of in situ (on-site) reinforcement consolidation and has furthered the practice of maintenance in situ when possible.With almost 20 years’ experience, Enzo is highly specialized in the conservation, renovation and restoration of antique mosaics.

The most common procedures concern: consultation, cleaning, conservation, consolidation and restoration, backfilling, lifting and transfer to a museum, lifting and re-laying in situ, and consolidation in situ.

Through the use of a special technique, it possible to relieve the mosaic of 70% of its original weight. The procedure involves injecting special mortars into the mosaic using syringes in situ, consolidating the piece, lifting and removing it from its original back and relocating the mosaic to a new, lighter surface.

Most of the old mosaics restored in the last century were mounted on weighty concrete and iron structures, very heavy and difficult to transport, which made it extremely difficult to move them. In fact, the mosaic and its back can weigh up to 650 pounds (300 kg) per square meter.Enzo removes the heavy back and reinstalls the mosaic onto a light, inflexible surface of aluminum honeycomb. This process eliminates roughly 70% of the total weight of the piece, with obvious benefits in terms of transportation and ease of delivery.

When an old mosaic is found in an archeological site, or when a client wants to remove a mosaic from his floor or wall and the he wants to reinstall it in a new location, Enzo uses specific swords to extract it  from its original location and then relocates it to the new destination site.

All antique Roman, Byzantine and micromosaics can be restored. Enzo is also highly accomplished at reconstructing ‘lost’ areas of mosaic, using the same kind of tiles to rebuild the damaged areas

Enzo Aiello  is highly specialized  in Restoration,Consolidation, Conservation,Detaching and Re-installation of ancient mosaics, including  Ancient Roman Mosaics from II century b.C. to IV century a.D,Ancient Byzantine Mosaics from IV century a.D. to VII century a.D, Middle Age Mosaics,Old Mosaics from VIII century a.D on up to contemporary mosaics.

Before to restore  “Ancient Roman Mosaics” from II century b.C. to IV century a.D. it is fundamental to know its stratigraphy.The following stratigraphy is adapted from ancient literary sources. It is to be used only as a general reference in this document. In practice, all ancient mosaics do not necessarily display this stratigraphy. A mosaic can be built on natural ground made of soil or rock, or on top of a previous pavement. The mosaic itself is composed of a variety of foundation or preparatory layers and a layer of tesserae. Usually the ancient Roman Mosaics from II century b.C. to IV century a.D  show the following stratigraphy:

1 – Statumen 

First preparatory layer which is made of large stones laid on the ground, previously leveled and rammed. This layer only exists if the mosaic has been constructed on a natural soil.

2 – Rudus –

Second preparatory layer which is spread over the statumen. This layer is made of a lime mortar with large aggregates.

3 – Nucleus –

Third preparatory layer which is spread over the rudus in a thinner layer. The nucleus is made of a mortar with fine aggregates.

4 – Supra Nucleus – (Bedding layer)

Fourth preparatory layer of mortar which is very rich in lime, and thinly applied in small sections over the nucleus. Tesserae are inserted in this layer before the mortar sets.

5 – Tessellatum –

Layer which consitutes the mosaic surface and is composed of tesserae and mortar filling the interstices between them.



Collection of background information and documentation on the mosaic,taking  detailed pictures of the actual conditions of the mosaic, information of the history of the site, documentation on previous restoration ,all the documents raised offer a better evaluation on the proper technology of restoration to use


Application of a material (natural or synthetic product) to restore cohesion to preparatory layers.


Application of material (natural or synthetic product) to restore cohesion to individual tesserae.


Application of a mortar along the edges of a mosaic.

5)      FACING

Application of gauze or similar material on the mosaic surface with an adhesive for its temporary protection during treatment

6)      GROUTING

Introduction of a fluid binder aggregate mixture into a void between preparatory layers

7)      FILLING

Application for stability of mosaic of a mortar and/or other materials in an area of loss of the mosaic surface.


Application of a mortar in the interstices between the tesserae.


Replacement of detached tesserae in their original position using an adhesive mortar.Removal of the old mortar, cleaning the cavity , setting new mortar and  filling new stones in the gaps where ancient stones are missing, according to the original design of mosaic


Reduction or removal of microbiological organisms by mechanical or chemical means.


Removal of extraneous substances from the mosaic surface, with or without water, and with tools such as sponges, brushes, scalpels, wooden tools, dental instruments, etc.


If  cohesion of TESSERAE in the weaker areas are ok, the preliminary operations for the complete facing of the mosaic can be carried out. Superficial deposits (earth, remains of mortar from previous interventions, loose incrustations) must be cleaned, to allow good adhesion between the tesserae and the layers of facing, and loose residues in the interstitial spaces between the tesserae are extracted with a vacuum cleaner. If there are areas of detached tesserae they must be temporarily reinforced with a very thin mortar which will be  packed into the spaces between the tesserae using palette knives, scalpels, and fingers

Sticking a gauze over the mosaic with soluble glue , Excavate a trench to have access to the bedding layers of the mosaic .  This trench will be excavated with appropriate archaeological techniques inserting specific  flexible iron“swords”in the “Rudus” to detach the mosaic from the floor


Once the mosaic is detached,removal of the mortar left on the back of the mosaics with wood chisels of various sizes, small saws, rasps, stainless steel brushes, natural and synthetic hard-fiber brushes,  scalpels and bisturi ,vibroincisors or electric saws like Makita power cutters . The aim is to remove all residual material of the mortar layers down to the thin stratum of the setting-bed as delicately and gradually as possible.Manual tools, which allow greater control over the depth of the work to avoid damaging the underside of the tesserae (particularly the very fragile glass tesserae), are therefore preferred.


Removal of residual concrete with a needle from the interstices in between the “tesserae”stones.After using abrasive and cutting tools to remove the disintegrated mortars of the preparatory layers, cleaning of the back of the mosaic continues using more precise tools. This operation is traditionally called the spillatura because it is carried out using spilli, small metal awls, although these are now supplemented with precision electrical instruments. The aim of this operation is to free the interstitial spaces of the tesserae ofresidues from the disintegrated setting-bed and of all traces of organic matter and earth accumulated between the tesserae during burial, which might interfere with adhesion between the mosaic and its new support. The residues from the cleaning operations will be removed using a vacuum cleaner.If necessary , the back of the mosaic will be disinfected using a biocide


of the mosaic with new mortar,thinset or binding resin in a new destination,(floor,wall,etc.) or on specific panels of Aereolam,aluminum honeycomb