Bethesda Terrace : conditions assessment and evaluation of previous stone conservation treatments

378 Pages·1998·5.8 MB·English

by  Gembinski, Christopher John

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BETHESDA TERRACE:
CONDITIONS ASSESSMENT AND EVALUATION OF PREVIOUS STONE
CONSERVATION TREATMENTS
CHRISTOPHER JOHN GEMBINSKI
A THESIS
In
Historic Preservation
Presented to the Faculties of the University of Pennsylvania in
Partial Fulfillment of the Requirements for the Degree of
MASTER OF SCIENCE
1998
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Su^rvnspr Supervisor
Frank-GrMatero A. E. Charola
Chair and Associate Professor of Lecturer in Historic Preservation
Architecture
Graduate Group Chair
Frank G. Matero
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Table of Contents
TableOFContents
'
ListOF Figures "v
ListOFTables v
Acknowledgements vi
INTRODUCTION 1
Objectives 4
PHASE CONDITIONS SURVEY AND PRELIMINARY RESEARCH
I:
CHAPTER PROJECT METHODOLOGY 6
1:
Documentation 7
CHAPTER CONDITIONS SURVEY 11
2:
Objective ''''
DesignOFtheTerrace 12
Sandstone ConditionsATTHETerrace 15
Research FORConditions Survey Development 17
AreasSELECTEDforconditionssurvey 19
PhotographyAND DrawingsFORthe Survey 21
GlossaryOF ConditionsCategories 22
PreviousLong-termLoss OFStoneMaterial 23
Discoloration/Deposit 25
RecentActiveDeterioration 27
FissuresandDeformation 29
Replacement 30
FormattingtheSURVEY 32
Descriptive SymptomaticConditionsTerminology 35
46
Digitization
PHASE ANALYSIS AND ASSESSMENT OF DECAY MECHANISMS AND PREVIOUS
II:
TREATMENTS
CHAPTER COMPARATIVE ANALYSIS 48
3:
Previoustreatments 48
Structuralmoisture penetration 50
Environment 52
Rate OFalterationANDdeterioration 54
CHAPTER FACTORS AFFECTING THE CONDITIONS OBSERVED 56
4:
Location 59
ConstructionANDDESIGN 60
Surface finishingOFthe stone 63
StoneTYPEANDCOMPOSITION 66
PastINTERVENTIONS 75

CHAPTER 5: CORRELATION AMONG CONDITIONS 76
Previous LONG-TERM Loss 77
DifferentialErosion, RougheningandRounding 77
Breakage 79
Previous LONG-TERMLOSSANDSALTS 79
Previous LONG-TERM LOSSAND moisture PENETRATION 80
RecentActive Deterioration 82
Granulardisintegration 82
Delamination, flakingandcrusts 83
Active deteriorationANDSALTS 84
Overallactivedeterioration 85
CHAPTER 6: CHARACTERIZATION AND ANALYSIS OF UNTREATED AND TREATED
STONE 87
PreliminaryOBSERVATIONS 91
TheArcade 91
RelativemoistureBYProtimeter™ readings 92
TheTerrace 95
ANALYSISOFTHE Sandstone 97
CapillaryAction 97
WaterPIPEABSORPTION 100
WaterAbsorptionBY Total Immersion 104
MeasurementOFTHEDryingIndex 107
Water Vapor Tfiansmission 109
ScanningElectronMicroscopy Ill
PowderX-RAYdiffraction 112
IdentificationOFSoluble Salts 114
CHAPTER 7: EVALUATION OF PREVIOUS TREATMENTS 120
HONING 120
Consolidation 123
Compensation 124
CompositePatching 125
ReplacementINKind 135
CONCLUSIONS
137
RECOMMENDATIONS
140
AppendixA: Interviews 144
APPENDIXB: AutoCAD DRAWINGSOFTHEconditionssurveyOFTHEarcade 147
PREVIOUS LONG-TERM LOSS
Drawing 1-CA Centralarcade 148
Drawing 1-EL Eastloggia 149
Drawing 1-NS North andsouth arcades 150
Drawing 1-WL Westloggia 151
III