Conservation in Malta

villa bologna

INTRODUCTION

METHOD STATEMENT

VILLA BOLOGNA SITE CONTEXT & HISTORY

BENCH AT SUNKEN POND

1. SITE CONTEXT

2. CONDITIONS ASSESSMENT

3. CONSERVATION TREATMENT

WALL AT MAIN NYMPHAEUM

1. SITE CONTEXT



CONTENTS

sunken pond

TITLE

5TITLE OF SECTION

INTRODUCTIONThis document is prepared by the students of the Boston Architectural College. Their findings and recommendations are based on their Malta Intensive Week Projects for the Architectural Materials Conservation: Philosophy, Methods, and Practice course.

Participants and contributors to this report:

Jacquelyn Connard

Danielle Encela

Julie Galluzzo

Janet Gilmartin

Joni Lane

Beth Paret

Elizabeth Rival

Ivan Santos-Diaz

Comprehensive Conservation Plan | Villa Bologna Method Statement

villa bologna & gardens

In late June and early July 2013, Robert Ogle, Director of Historic Preservation at Boston Architectural College, conservator and course instructor Mike Riegert, art conservator, Maria Borja, and a diverse group of BAC

students traveled to the historically significant Baroque period estate of Villa Bologna, in the city of Attard, in the Republic of Malta to document and execute conservation interventions on two separate sites within the estates

fortified walls. The goal was to conserve and repair two endangered structures, a Baroque period limestone bench overlooking the “Sunken Pond” and a wall abutting a fountain known as “the Main Nymphauem.”

These two particular structures were identified by Jasper de Trafford, steward and owner of the Villa, for their intrinsic value, architectural significance, and importance as a part of the future of the villa.

The course instructor, Mike Riegert, along with owner Jasper de Trafford, have followed the guiding philosophy of minimal intervention for all conservation treatment designs for these site

projects. In addition to prioritizing the stability of these project sites, minimal intervention seeks to maximize the compatibility of materials used in treatment, maximize the authenticity of the treatment outcome, ensure reversibility of treatment, all with the aim of doing no harm.

METHOD STATEMENT

SITE CONTEXTVILLA BOLOGNAATTARD, MALTA MT

Villa Bologna is an eighteenth century walled compound set in the beautiful, historic village of Attard, a small municipality dating back to the Classical period, which is currently home to about 10,000 people. Attard is located in the center of Malta, an island south of Sicily, surrounded by the Mediterranean Sea.

Comprehensive Conservation Plan | Villa Bologna Site Context

OVERALL

9OVERALL SITE CONTEXT


LOCATIONVILLA BOLOGNA

Situated on Trig St. Anton (St. Anton Street), Villa Bologna is one of the most prominent properties in what many consider the finest residential area of the island.

Villa Bologna is only steps from San Anton Palace, the residence of the Maltese President (figure 1) and its official botanical gardens, the American Ambassador’s residence and St. Catherine’s nursing home. The neighborhood surrounding Villa Bologna boasts a combination of converted farmhouses and stately homes. Many of the latter were former residences of the Knights of St. John.

During the 1980’s, a substantial amount of development occurred in the area surrounding the center of the village. Modern apartment buildings are now unfortunately visible, as shown in figure 2 from the Villa gardens. On the other sides of the Villa, The Ambassador’s residence and Palace have not been affected.

Figure 1

Figure 2



HISTORY & SIGNIFICANCEVILLA BOLOGNA

In 1745, the eight acre estate was built by Fabrizio Grech as a dowry for his daughter, Maria Teresa, who married Nicolas Paerdicomati Bologna, the second Count della Catena. The main house, baroque fountains, mediterranean gardens and original orange groves for which the villa is best known, all date from this period. The villa has served as a residence for generations of his descendants ever since.

“Fabrizio Grech, a noted lawyer and legal advisor to the Knights of St. John, Grandmaster Pinto, gave this fabulous villa as a wedding present to his daughter. Henceforth it came to be known as Villa Bologna. Almost 200 years later it became the private residence of Lord Gerald Strickland, Count della Catena, who became Prime Minister of Malta in 1927.


The family associated with the villa has a long history with Noble links and links to Maltese and British political history, since it was the former residence of Sir Gerald Strickland (also known by the title of Lord Strickland) and his prominent family.

Sir Gerald was born in Malta in May 1861 and was educated in Malta, Great Britain (including Cambridge) and Italy. He took and active part in politics, both in the U.K and Malta, serving as a Member of Parliament in England and becoming involved in Maltese politics at an early age.

Sir Gerald returned to Malta in 1921 and founded the Anglo-Maltese Party, which merged with the Maltese Constitutional Party shortly thereafter. He became “head of Ministry” and served as the Fourth Prime Minister of Malta from 1927 to 1939. He was knighted a Companion of the Order of St. Michael and St. John for his efforts.

The Villa was bequeathed to Lord Strickland in the 1930’s. After the death of his wife, he remarried to Lady Mabel. She enriched the landscape of Villa Bologna by designing a new garden behind the villa, complete with a sunken pond, surrounded by perennial gardens, fig trees, two baroque limestone benches, pergolas, garden ornaments, and orchards containing a variety of citrus trees.

Now used as a gathering spot for weddings, artists, schoolchildren, concerts, and walking tours, the villa also has a community supported garden, ceramic pottery shop, and a store front in which to sell its wares. They focus their gardening efforts on sustainable organic farming practices for the wholesale market. Future planned uses include: corporate meeting space and an on-site café.

Our preservation efforts focused on two distinct structures on-site: a bench at the Sunken Pond and a wall adjacent to the Nymphaeum.

Sir Generald Strickland

Mabel Strickland stands in the hole made by a World War II bomb that caused part of the damage now being repaired. Photo provided by the De Trafford family.

GEOGRAPHY, TOPOGRAPHY AND WEATHER CONDITIONS


VILLA BOLOGNA

Latitude: 35o 89’50” N

Longitude: 14o 44’36” E

Height above sea level: ≈ 100m

Area: ≈ 8 acres

Topographical features: gardens, agricultural fields, underground reservoir

Climate: Sub-tropical MediterraneanRelative humidity: 40%Avg. annual rainfall: 24 inAnnual mean temp: 64o

Winds:A cool NW wind is the most common. SE winds bring humidity. NE winds are dry.

Avg. length of sunlight (in hrs.):Winter 5-6Spring 7-9Autumn 6-9 Summer 11-12


Comprehensive Conservation Plan | BENCH AT SUNKEN POND

BENCHAT SUNKEN POND

17BENCH AT SUNKEN POND

1. SITE CONTEXT



SITE CONTEXTBENCH AT SUNKEN POND

Aspect:

South East

Environment:

Situated atop limestone pavers

Partially shaded by a tree

Abutting a man-made pond

Situated diagonally from a birdhouse

Adjacent to agricultural garden beds

Across from identical bench on the opposite side of the pond

History:

Initially used as part of the private residence, now used by outside groups in conjunction with weddings & receptions, tours, film & TV series backdrops, etc.

Anthropogenic changes are likely to accelerate with increased usage.

Materials:

Globigerina limestone

Past restoration:

Complete replacement of one end section with new limestone

Application of cement mortar


19SITE CONTEXT

CONDITIONS ASSESSMENTCURRENT STATE

Crack and Deformation

Large fissures were observed on the ridge line in the center/posterior section of the bench, resulting in deep depressions. The degree of material loss might be attributable to the quality of stone used in this section.

Cracks were also noted on the ridge of the anterior (original) portion of the bench. It is possible that these large cracks were once smaller, individual micro-fissures that merged together over time. Where the bench is situated atop soil, it’s also possible that capillary action introduced some of the moisture and salts into the bench’s fabric, which contributed to the material loss.

Past repointing efforts using cement were clearly visible on certain sections of the bench, particularly on the finials shown above. Cement is known to cause cracking of the surrounding substrate as its hard, low-porosity nature encourages salts to migrate around it since they are unable to penetrate it.

Detachment

Extreme friability was observed on the posterior of the bench as a result of scaling. In this process, “scales,” so named because of their similarity in appearance to fish scales, are shed from the stone’s surface.

The shedding does not occur in a uniform manner, thus leaving an irregular surface in its wake. Scales are normally quite thin, ranging from millimeters to centimeters. However, the resulting depressions invite further deterioration as they create niches for salt crystals to accumulate in, which crack under pressure and create even larger areas of damage.


Detachment & alveolization

21CONDITIONS ASSESSMENT

Features Induced by Material Loss

Alveolization of the stone surface is present in each section of the bench save for the reconstructed portion. This has rendered the surrounding fabric extremely friable in areas.

Exposure to the elements (weathering) results in wet/dry cycles on the stone surface. Salts are introduced into the pores of the fabric, which expand and crack over time. The larger pores created by this action thus invite larger salt deposits, causing an acceleration of the decay.

Large alveoli are commonly formed in arid climates, such as in Attard.

Differential erosion is also present on the structure; the various surfaces are not deteriorating at the same rate or in the same fashion. According to the ICOMOS Illustrated Glossary on Stone Deterioration Patterns, this phenomenon is generally found on sedimentary stones, like limestone. Additionally, limestone contains calcite, which is vulnerable to lichen attack, which could further accelerate the erosion. (p. 34)

Discoloration and Deposit

Exogenic deposits identified on-site as originating from local wildlife were noted on several horizontal planes. There is a bird house in close proximity to the bench, which is likely a contributing factor to the deposits. Such deposits are not normally strongly adherent to the substrate.

The darkened areas on the stone do not qualify as deposits, as they are in actuality biological colonization.

Biological Colonization

Algae are visible over a large percentage of the bench, presenting as a black discoloration. In the dry season (when these photographs were taken), algae turn this darker color, which can cause it to be confused with black gypsum crust. Algae can be removed by cleaning, as shown to the right.

Elsewhere on the bench a polychromatic bio-film of algae can be observed.

Vegetation had also infiltrated the bench; roots from the sheltering tree were found running beneath the limestone pavers directly beneath the structure, threatening it s fabric.

PLANFRONT ELEVATION

BACK ELEVATION ARM REST ELEVATION PARTIAL ELEVATION

RESTORATION AND MAINTENANCE WORKS OF STRUCTURES IN THE GARDEN OF VILLA BOLOGNA

STONE BENCH @ SUNKEN POND - EXISTING CONDITIONS

VILLA BOLOGNA, SAN ANTON STREET, ATTARD 1282 MALTA SL7105 - ARCH. MATERIALS CONSERVATION: PHILOSOPHY, METHODS & PRACTICE

24/07/2013

D.ENCELA

D.ENCELA

M.RIEGERT

A020

PLANFRONT ELEVATION



STONE BENCH @ SUNKEN POND - EXISTING CONDITIONS


24/07/2013

D.ENCELA

D.ENCELA

M.RIEGERT

A020

PLANFRONT ELEVATION


CRACK & DEFORMATION

FRAGMENTATION

DISCOLORATION & DEPOSIT

LEGEND

MISSING PART

BIOLOGICAL COLONIZATION

MECHANICAL DAMAGE

ALGA

ALVEOLIZATION

DETACHMENT


STONE BENCH @ SUNKEN POND - CONDITIONS ASSESSTMENT


24/07/2013

D.ENCELA

D.ENCELA

M.RIEGERT

A120

E

PLANFRONT ELEVATION


CRACK & DEFORMATION

FRAGMENTATION

DISCOLORATION & DEPOSIT

LEGEND

MISSING PART


MECHANICAL DAMAGE

ALGA

ALVEOLIZATION

DETACHMENT


STONE BENCH @ SUNKEN POND - CONDITIONS ASSESSTMENT


24/07/2013

D.ENCELA

D.ENCELA

M.RIEGERT

A120

CONSERVATION TREATMENTCONSERVATION METHODOLOGY

1. Removal of Vegetation

2. Cleaning

3. Plastic Repairs

4. Natural Hydraulic Lime Injections

PREPARATION FOR REPAIR

Removal of Vegetation

Using hand pruners and small saws, encroaching roots and branches of a fig tree that had subverted the bench and surrounding pavers were removed. Special care was taken to not damage the stone with the metal tools during the removal process.

Recording Dimensions and Profiles

After the removal of all obstructions and buildup on or around the bench, measurements were taken in order to precisely document the existing stonework.

Cleaning

In order to effectively prepare the stone surface for conservation treatments/interventions, as well as to remove encroaching vegetation, the following methods were used. Care was taken to ensure that the cleaning process did not damage friable areas of stone.

Dry Brushing by Hand

Beginning with soft nylon bristled brushes, the bench was gently cleaned of all loose dirt and debris. Stiffer brushes were then used to remove stubborn dirt and stains.

Wet Brushing by Hand

In areas with a buildup of lichens and algae, a soft bristled brush soaked in clean water was used to remove the biological colonization. First, the area to be cleaned must be pre-wetted as well as the area beneath the biological colonization. The pre-wetting prevents streaking and staining from runoff produced during the cleaning process.

Raking out Joints

Scalpels and small metal dental tools were used to remove deteriorated mortar from the joints of the bench.


27CONSERVATION TREATMENT

Dry brushing by hand before and after (above & left) and wet brushing (right).

CONSERVATION TREATMENTS

Plastic Repair

Delamination, splitting, alveolarization, erosion, of areas on the bench were addressed through plastic repair. Ensuring that the stone was kept moist for proper adherence, plastic repairs were performed on degraded areas using a sand and lime mix repaired onsite. A 1:3 mixture of sand and Natural Hydraulic lime (NHL) with additional pigment added to match the stone was tested to ensure proper match in texture and color, then used on the affected areas. This sand and natural hydraulic lime mix was used to fill in the large cracks and alveolar present on the surface of the stone. The filling of these friable areas prevent the further infiltration of water into the affected areas, slowing the decay caused by salt crystallization from the wet/dry cycle.

Special care was taken to preserve the original form and profile of areas with ornamental decoration while executing plastic repair.

Micro-crack Injections

The administration of a lime and sand injection to the small cracks, fissures, and hollow areas of the bench added stability to areas unreachable by normal plastic repairs.

Pointing

Repointing with a lime and sand mixture was applied along the seams between the bench sections and where the seat meets the bench back to prevent water infiltration


Top: 1:3 mixture for plastic repair Middle: Plastic Repair

Bottom: Pointing

29CONSERVATION TREATMENT

Micro-crack Injections

WALLAT MAIN NYMPHAEUM

35WALL AT MAIN NYMPHAEUM

1. SITE CONTEXT



SITE CONTEXTWALL AT MAIN NYMPHAEUM

Aspect:

South West

Environment:

Un-shaded environment

Adjacent to the large water fountain ‘Nymphaeum’

Adjacent to a large citrus grove

Proximal to the main residence, significant foot traffic

Shares a corner with an exterior staircase wall

History:

Initially used as part of the private residence, now used by outside groups in conjunction with receptions, tours, etc. Anthropogenic changes are likely to accelerate with increased usage.

Materials:

Globigerina limestone

Past restoration:

Partial reconstruction after WWII due to bomb/artillery damage

Repointing of mortar including the use of organic filler material (wood shards, etc.)

Evidence of past restoration of refurbishing attempts as efident in repairs, veneer-style stone changes, renders and portland based cement mortars.

Comprehensive Conservation Plan | WALL AT MAIN NYMPHAEUM

37WALL SITE CONTEXT

CONDITIONS ASSESSMENT

CURRENT STATE

Crack and DeformationSome splitting was noted on individual stones. Oriented vertically, these cracks normally indicate an area buckling under a weight load. The loss of material due to weathering has weakened the substrate, thus negatively affecting its ability to support the higher stone courses.

Detachment

Granular disintegration and crumbling are notable across the wall’s surface. Deposits present in some areas at the foot of the wall, indicate the material had fallen from above once it detached. Powdering (associated with granular disintegration) was also present; a sweep of the hand across the surface left behind a powdery residue.

All of these various damages were caused by the mechanics of soluble salt infiltration and the wet/dry cycle that creates the deposits which eventually rupture the building fabric.


39WALL CONDITIONS ASSESSMENT

Features Induced by Material Loss

Deep alveolization of the stone surface is unilaterally present. As with the bench, soluble salt crystallization is the main culprit.

The absence of mortar in many of the wall’s joints has allowed for the migration of salts to the limestone substrate.

Coving (concavity of the stones in certain areas) is present on the lower courses of the wall. (See lower photograph)

It is also possible that rising damp from the earth at the base of the wall (a process of leaching water through the capillary action of the stones) has contributed to the poor condition of the substrate at this level. Higher courses of stone do not display the same degree of deterioration.

Discoloration and Deposit

Efflorescence is displayed over a broad area of the wall. The white crust-like appearance on the stones’ surfaces are actually soluble salts formed within the limestone itself. They are not a deposit (left by external forces).

The reddish brown discoloration on the mid-to-upper courses of stone is likely an oxalate patina, commonly found on limestone structures in an outdoor environment.

Biological Colonization

The presence of vegetation growing amidst the limestone substrate both here and along the foot of the wall indicates the presence of moisture somewhere within the stones. The wall should be thoroughly examined to locate the water’s path in an effort to remediate it and prevent future plant growth.

Algae, often confused with black crust because of its dark appearance, are present across the wall’s surface. This type of colonization is common to outdoor areas like the wall, which is not protected from rains. The algae are not strongly bonded to the substrate, as a black crust would be.


41WALL CONDITIONS ASSESSMENT

SIDE ELEVATIONFRONT ELEVATION


WALL BY MAIN NYPHAEUM - EXISTING CONDITIONS


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D.ENCELA

D.ENCELA

M.RIEGERT

A010



WALL BY MAIN NYPHAEUM - EXISTING CONDITIONS


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D.ENCELA

D.ENCELA

M.RIEGERT

A010

DISCOLORATION

FRAGMENTATION


WALL BY MAIN NYPHAEUM - CONDITIONS ASSESSMENT


24/07/2013

LEGEND


D.ENCELA

D.ENCELA

M.RIEGERT

A110

EFFLORESCENCE


MECHANICAL DAMAGE

ALVEOLIZATION

DETACHMENT

DISCOLORATION

FRAGMENTATION


WALL BY MAIN NYPHAEUM - CONDITIONS ASSESSMENT


24/07/2013

LEGEND


D.ENCELA

D.ENCELA

M.RIEGERT

A110

EFFLORESCENCE


MECHANICAL DAMAGE

ALVEOLIZATION

DETACHMENT

CURRENT STATE OF DETERIORATION

Due to the presence of severe back weathering and erosion, exacerbated by the loss of much of its pointing, a section of the wall located directly north of the Large Nympheum was targeted for emergency repair.

Restoration Methodology

1. Cleaning

2. Repair

PREPARATION FOR REPAIR

Cleaning

In order to effectively prepare the stone surface for the repair work, the following methods were used. Care was taken to ensure that the cleaning process did not damage friable areas of stone.

Recording Dimensions and Profiles

Photos and measurements were taken in order to precisely document the existing stonework and areas of decay.

Dry Brushing by Hand

Using the softest available brushes, the wall was cleaned of all loose dirt and debris.

Raking out Joints

Deteriorated mortar was removed from the joints between the limestone blocks constructing the wall.

Monitoring

All cleaning of the wall was closely monitored to ensure no damage was done to the surface of the stone.


CONSERVATION TREATMENT

CONSERVATION TREATMENTS

Pointing

Repointing of the stone wall was conducted with a lime and sand mixture. Repointing these areas prevents further water infiltration which, if allowed to continue would accelerate the degradation of the masonry units.

Ensuring that the stone was kept moist for proper adherence, repointing was performed on areas of the wall where the existing pointing had failed or deteriorated. A sand and lime pointing mixture made up of 1 part Natural Hydraulic Lime (NHL) to 3 parts sand was used to repoint the affected areas. The NHL used in this project was rated 3.5, mid-strength, and produced by the Lafarge Company. This 1:3 proportion of NHL to sand was used to fill all deteriorated joints between the stones of the wall.

The pointing mixture was applied both by trowel, and by harling or “pitch method” in order to ensure proper coverage and adherence in the deeply eroded joints. Left - Students at work pointing

Above & below - Post-treatment completed wall

TREATMENTS

Maltese Limestone QuarryCover: Main Nymphaeum Fountain

Documents

Conservation in Malta