Probota Monastery: The Mural Paintings

A mural is a general term for a painting applied directly to a wall. The original 16^th century paintings at Probota were executed a fresco. Upon a prepared wall, the artist painted directly on the wet rendering, a special type of plaster. But the artist only plastered an amount of wall space which could be painted in a day. A trained eye can see these daily patches, called giornate, in the frescoes today.

The rendering upon the wall, which serves as the plaster canvas, has at least two layers. The first layer is the arriccio layer, composed principally of slaked lime, sand and/or brick dust and organic matter, such as chopped straw. Atop this goes the intonaco layer, a much finer layer intended for painting. Restorers found that Probota has no arriccio layer, but double a intonaco layer.

The fresco mural technique is extremely durable. When the lime-based rendering dries, it carbonizes and binds the colors of the paints. Given good conditions, frescoes can last indefinitely. For nearly half a millenium, the paintings of Probota have endured weather, earthquakes, neglect and modern encroachments like pollution.

Between 1844 and 1848, the interior of the church was over-painted. These "restorers" used a different painting technique called a secco. This technique relied on a binder, commonly egg whites, to make pigments stick to the walls. The different techniques complicated the restoration proceeding today.

After the over-painting in the 1840's, the mural paintings at Probota were not subject to other important interventions. However, untrained persons attempted several cleanings to various paintings which worsened the situation.

In 1992, with the help of the Archbishopric of Radauti and Suceava, a wooden scaffolding was erected inside the church. A group of Romanian restorers consolidated the areas with lacunae - gaps in the frescoes - and spots where the rendering had detached from the masonry.

The following year an emergency operation focusing on the exterior of the church was initiated by the Director of Historical Monuments. Outside, exposed to the elements, the rendering layers not only detached from the masonry, but from one another. To consolidate the rendering, liquid mortar was injected between layers.

A comprehensive conservation effort for the outside murals began in June 1997 on the northern façade. Work began with stratigraphical, chemical and biological analyses. These preliminary tests identified the type of masonry, the different rendering layers and the composition of the paint layer itself.

Almost 90% of the northern façade was affected by biological attack. High humidity encouraged the rapid growth of lichens, fungi, mosses and algae. Lichens of various colours covered all surfaces except for the highest part of the façade under the eaves. Curiously lichens, which metabolize stone and minerals, avoided blue and green pigments.

The moisture also caused salt efflorescence which appeared in the form of a greyish caking. The humidity produced by rain had also eroded the rendering layers down to the painted brick beneath. Around buttresses, windows, as well as the upper part of the cornice and the niches, the detachment of rendering was pronounced. Another consequence of the humidity was chromatic alteration. Blue pigments turned green.

To control and prevent further growth of lichens and other biological agents, restorers applied a biocide. Once the lichens dried, their fruiting bodies were removed by hand with scalpels. Areas with visible traces of paint were first treated with a fixative. This helped to prevent the inadvertent removal of any paint layers or limewash.

After the biocide treatment, the broken edges of rendering were hemstitched. Hemstiching improves the adherence of rendering to other stratas. This procedure is especially important at the margins of the paint layer and weak joints, such as the seam between the plaster and the stone frames of windows.

Detachments were identified with an acoustic examination. Most frequently detachments occured between plaster and masonry or between two types of plaster. Sometimes, the lime wash layer detached itself together with the paint layer which necessitated pre-consolidation. The first lime wash layers were mechanically removed, while the following very thin ones were dissolved chemically.

The consolidation of the paint layer was carried out using barium hydroxide and ammonium carbonate. Consolidation of the brick and stone masonry, as well as of the intonaco layer, was also necessary. This was done with injections, brushing or spraying of consolidating solutions. Deep lacunae of the masonry were filled with a coarse mortar. New bricks replacing old ones were used to fill lacunae at the level of the niches.

The lacunae of the intonaco layer were reconstructed slightly below the original level. The first layer of filling was lightly coloured to represent the original decorations of brick motif, and the second one was white. Where the original brick motif layer was preserved no other intonaco was added. The lacunae in the paint layer were filled with mortar.

The restorers encountered various problems indoors as well. Salt efflorescence threatened the murals. These begin with moisture being drawn into porous walls. Through the capillary effect, water rises as does a liquid in a straw. Minerals dissolve in this water. When it evaporates, salt efflorescence forms as crusty deposits.

Inside the church, the presence of salts was detected up to a height of 2.5 to 3 metres. The less soluble salts gathered lower down the walls. More soluble salts rose and evaporated higher up. The rain, coming through a leaky roof, left efflorescence on the upper reaches of the church walls. On the northern wall of the pronaos the salts were mainly potassium; on the southern wall, sodium. The eastern part of the pronaos had sustained more damage than the western one.

Generally speaking, salts do not grow if the relative humidity is kept below 65%. The relative humidity, air temperature and surface temperature of the masonry were recorded with a thermohygrometer. Keeping the room temperature and relative humidity values constant is the best way of keeping salts under control. Water infiltration through the roof was corrected simply by repairing the roof.

Salts and damp had facilitated the adherence of dust and spores, which cultivated micro-organisms. Analysis showed that these micro-organisms were different species of bacteria, actinomyces and fungi. Lichens mottled murals in reds, grey-greens and browns.

After analysis, the first stage of restoring and conserving the murals began with cleaning them. Dust and the soot from candles coated the paintings. These layers were not too thick given the over-painting done in 1840's. But the over-painting caused other problems.

The burial chamber, the naos and the chancel were repainted in 1844. On this occasion the original composition was followed, but the style and chromatism, or colouring, changed. Also the differences in painterly techniques -- a fresco vs. a secco -- complicated restoration. When the interior was overpainted the artist used the secco technique with a protein binder. This caused the layer to become rigid and scale, which has made the cleaning of the portraits especially difficult.

Superficial gaps, powdering and scaling typified the other kinds of degradation affecting the paint layer of the murals. Restorers classify these as adherence problems. The background of the murals has resisted them well. The painters used azurite for the sky and malachite for the earth and applied them in a proper fresco form. Consequently, the blues and greens were better carbonised and conserved.

The details, such as flesh tones, were made with clay pigments. Clay has only average resistance so powdering had occurred. The portraits and the hands made with clay pigments, especially ochre red, mixed with lime, were the most sensitive areas and were scaling and swelling.

The over- painting was removed with compresses of ammonium carbonate, or where more delicate, with an ion-exchange resin applied through Japanese paper. The compresses with long action time proved to be efficient against salts, and also pre-fixed the colour. The blue azurite pigments were cleaned with a solution of water and ethyl alcohol

Cleaning with ion-exchange resin

Cleaning of the azurite layer with a compress

The traces of lime drops and mortars were removed mechanically, with scalpels, wooden blades and glass fibre brushes. Some very hard salt encrustations had to be removed by a special drill from the lower parts of the drapery.

Removing of lime drops with a glass fibre brush

Consolidation of the paint layer was mostly carried out during cleaning. Deep detachments of the supporting layers were grouted with injections of liquid mortar, while the more superficial ones were stabilized with a fixative.

Consolidation of layers with mortar

The old and inappropriate fillings of lacunae – missing pieces of fresco – were removed, and the edges were hemstitched. The new fillings were done 2 mm lower than the original level to show the difference between original and new. Using watercolour glazes the mortar has been tonally matched to the surrounding colours so not to distract the viewer’s eye. This method is called acqua sporca.

Retouching using the method of acqua sporca

Burial chamber: Southern wall before conservation

Burial chamber: Southern wall after conservation

Fragments detached form the lower part of the frescoes were consolidated and placed in their original position. Graffiti scratched on most walls dates from the late 16th century until 1996. These were left in place, but toned down in colour.


Burial chamber: Northern wall, Pious St. Hariton, before conservation	Burial chamber: Northern wall, Pious St. Hariton, after conservation
Using watercolour glazes the new mortar has been coloured slightly brownish grey to match the natural patina. This method is called acqua sporca and it is used to emphasize the difference between the original and the new.


Burial chamber: Northern wall, St. Hierarch Gregory, before conservation	Burial chamber: Northern wall, St. Hierarch Gregory, after conservation
For liturgical reasons some places, as the Christ Pantocrator of the naos vault, have been integrated with matching colours with the tratteggio method. This means that the lacunae are filled with tiny lines and slashes to show from near the difference between old and new.