Stabilization And Treatment Of Corroded Glass Objects -Books Pdf


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delivered to the Conservation Department of the same University where they seemed to me a good example of objects of completely corroded glass. The aim of the present work was to operate a scientific technique for stabilizing the corrosion process and treating these corroded glasses with suitable mechanical and visual properties. Solving this ...

INTRODUCTION In the recent years several studies on
corroded glass are of chemical and
The mentioned glass objects were
treatment interests have been performed on
delegated from the Department of
which the present study based and the
Antiquities of Jordan Irbid Archaeological
following principles are established
Museum to the Museum of Jordanian
Heritage in Yarmouk University in 1988 1 In the past new conservation treatments
Since this date they are displayed together were applied directly to archaeological
in the ground floor of the later museum with material This is now considered
other metal stone and pottery objects in the inappropriate so a standardized testing
hall no 3 inside the case no 3 Based on the procedure must be established The
stylistic and technological considerations treatment must not damage the object
except the nursing glass no A00 that dated The treatment must be reversible The
to Roman Byzantine period in Mesopotamia long term effects are known Faltermeier
the other three objects were attributed and 1998
dated to the Roman period 1st 4th cent 2 The correct conservation treatment must
AD Archaeologists presume that they may be used to safely arrest the decay of the
be obtained from ruins of Tabaqat Fahl Pella object and minimize any risk of damage
the ancient Roman city in northern Jordan to the object in application of the
which was a part of the region of Decapolise conservation treatment Caple 2003
a union of the Roman cities in Jordan Abd 3 In the case of corroded glass it is
Alla 2006 In June 2006 they were important to understand that cleaning
delivered to the Conservation Department of means the removal of soil or deposits and
the same University where they seemed to encrustation but not removal of any
me a good example of objects of completely opaque weathering crust or a patina
corroded glass which has a protective action and
The aim of the present work was to archaeological feature this is destruction
operate a scientific technique for stabilizing for it is removing some of original artifact
the corrosion process and treating these Its removal means that the original
corroded glasses with suitable mechanical surface of the glass is destroyed and the
and visual properties Solving this task is thickness of the piece an important
the more important as there are many glass parameter technologically and for
objects in the museums in danger of being reconstruction is altered Removal will
lost through continuous corrosion and reveal a core of glass and unintentionally
aging remove evidence of the object s past
Cronyn 1990 and Abd Alla 2005
Museum Pervious Acquisition Source Description Photo
No A301 No J13669 Loan Department of Glass plate ring base
Antiquities of Jordan Irbid blue green color
Archaeological Museum Roman period
No A612 No 1599 Loan Department Glass vase
of Antiquities of oval body shape
Jordan Irbid concave base
Archaeological Museum polychrome color
Roman period
No A613 No 1717 Loan Department of Glass vase rounded
Antiquities of body high wide neck
Jordan Irbid concave base
Archaeological Museum polychrome color
Roman period
No A00 Loan Mr Lutfi Al Soumi A nursing bottle rounded
collection Syria body with a side hole
high wide neck concave
base polychrome color
Roman Byzantine period
Table 1 The registration data of the glass objects
Adapted from the Documentation Dept of the Museum of Jordanian Heritage
EXPERIMENTAL WORK the underlying glass core has become so
weakened through deterioration that pieces
Optical examination are falling away A trace of soil deposits and
The preliminary examination by the dirt were observed inside the hollow objects
critical eye and a magnifying hand lens no A612 A613 and A00 Furthermore
x10 indicate that these glasses are varied remains of weathering crusts which flaked
in their decay rate and corrosion nature It away from the interior surfaces also
seems likely that the weathering crusts observed and collected for chemical
found on the object no A301 and A612 are analyses microscopic examination and
an extreme form of the stone like experimenting the materials and methods
weathering extremely hard and flinty of treatment
Whereas the surfaces of the objects no
A613 and A00 are covered by a thick Microscopic examination
opaque blackened enamel like weathering Some invaluable corrosion crusts flaked
surface which in some areas has flaked away and separated from the glass surfaces
away to reveal an iridescent layer beneath a were collected and investigated by scanning
variegated coloration of the glass surface electron microscopy SEM model Quanta
The corroded surfaces had become very soft 200 in the Department of Earth Sciences
powdery and easy to destroy Furthermore Yarouk University in Jordan SEM was
Fig 1 A secondary electron image of a cross Fig 2 A backscattered electron image of fragile
section through corroded crusts from the glass crusts of glass bottle A612 showing large areas of
plate A301 showing deterioration proceeding the weathering crusts be destroyed and rich in
from the surface to the interior dissolution voids
Fig 3 A backscattered electron image of corroded Fig 4 A secondary electron image of a cross section
crusts of glass bottle A613 showing the through corroded crusts of the bottle A00 The
weathered layers be destroyed and losses its distinction between original glass leached layer
glassy nature and surface crust cannot easily be made
operated in both backscattered and planar and highly fractured forms Large
secondary electron modes to examine both areas of the weathering crusts were
the compositional phases and the surface destroyed and rich in dissolution voids and
structure of the glass material From SEM microcracks Addition to that other aspects
observation of the corroded glasses it can of sugar like surface flaking and highly
be seen that all the glass surfaces seem to be fissured nature of decayed crusts were also
inhomogeneous pitted curviplanar surface observed Figures 1 and 4 shows secondary
electron images of magnified sections to the inappropriate displaying in the
through corroded crusts from glass bottles museum There is an obvious change in the
no A301 and A00 showing deterioration compositions of the outer weathering crusts
proceeding from the surface to the interior in comparison with the interior glass cores
In all that cases no presence of crystals or underlying them i e sodium and potassium
devitrification was observed Abd Alla content decreases Na2O avg 2 59 and
2007 K2O avg 1 08 and Silica content
increases SiO2 avg 78 29
EDX analysis
An energy dispersive X ray instrument METHODS OF TREATMENT
model Philips XL30 with accelerating
voltage 30 K V attached with the
The glass surfaces of all the objects were
mentioned SEM system was used for
very brittle and easy to flake off and on the
determination of the chemical composition
surfaces were found several cracks In
of corroded glasses Analyses results given
addition no thick cores of original glass
in Table 2 indicate that these glasses
were found which excluded the use of
identified as potash lime silica K2O CaO
mechanical methods to remove soil deposit
SiO2 glass and characterized by high
and dirt As the water and moisture are the
potassium and magnesium content This
most important factors initiating and
composition indicates also that they made
sustaining forms of glass decomposition
with plant ash soda as a source of alkali
even damage caused by dehydration is
Furthermore it is in agreement with the
consequence of previous attack by water
results of recent studies of Al Ahmed and
Newton 1989 therefore wet cleaning
Al Muheisen 1995 Brill 1999 and
using water also excluded hence chemical
Abd Alla 2006 about the chemical
cleaning using organic solvents had to be
composition of the Roman and Byzantine
applied here Cotton swabs saturated with
glass in Jordan and Mesopotamia
acetone topically used for delicate cleaning
Chemically these glasses are completely
work Sease 1994 This cleaning method
decomposed due to attacking of the
has two advantages it does not damage the
intensive deterioration factors especially
glass surface and the visual appearance of
water for long time in the ground and due
surface iridescence not destroyed
Table 2 The chemical compositions of weathering crusts of glass objects obtained by EDX analysis
Stabilization this process was carried out of the four
According to the American Institute for glasses through the following tow
Conservation of Historic and Artistic Works procedures
AIC definitions of conservation
1 Chemical stabilization
terminology stabilization scientifically
The chemical stabilization were carried
means treatment procedures intended to
out of the four glasses through creating a
maintain the integrity of cultural property
chelation process using the chelating agent
and to minimize deterioration Caple
ethylendiaminetetraacetic acid EDTA
2000 mentioned that stabilization is the
HOOCCH2 2NCH2 According to several
act of preservation by causing the creation
successful experiments had previously been
or slowing to a minimum rate of the decay
carried out in similar cases it is generally
process This requires the identification of
accepted as the most effective chelating
the cause of decay and its mitigation which
agent recommended for cleaning
can be achieved through preventive or
encrustations on glass surface and acts
interventive conservation Any stabilization
chemically to inhibit or prevent further
treatment normally seeks to retain the
glass corrosion depending on its
object s present visual form Decay and
concentration and pH value It was more
stabilization processes occur in three
effective at neutral pH with low
categories biological chemical and
concentrations around 5 10 Paul
physical Stabilization processes can be
1978 Ernesberger 1978 Newton 1989
achieved through these categories as
Calt and Spare 2004 and Abd Alla 2005
follows biological immobilize organisms
A neutral solution of disodium salt of EDTA
by removing reaction agent O2 H2O heat
pH 7 at 5 concentration was applied for
light chemical remove reaction agents
all the glasses by brushing technique the
O2 H2O heat light catalysts and
use of soft paintbrush The aim of this
Physical eliminate reaction agents force
treatment was to arrest the continuity of
H2O consolidate protect or support
corrosion reactions and to prevent any
However the stabilization of the glass as of
expected devitrification to occur This
all materials falls into two main categories
treatment successfully carried out no
damage of weathering crusts was observed
a Active stabilization
and the visual appearance of iridescence not
This process means the treatment of
glass to arrest decay and to stabilize them
where possible There are several aims 2 Physical stabilization
involved in the active stabilization of As the glass objects are completely
weathered glass First water must be corroded or decomposed and their surfaces
removed without the crust shrinking are fragile and liable to crumble or flake
exfoliating crumbling second the crust upon drying or handling therefore
must be consolidated third it must be consolidation of these objects became
reaffixed to any glass core remaining and necessary to undertaken There are several
fourth where possible transparency must aims involved in the consolidation process
be reintroduced The last aim needs of these corroded glasses First to
qualifying where glass shows slight strengthen the underlying glass core
iridescence this type of crust is said to be a second consolidate the weathering crusts
patina giving beauty to the object However third reaffixed the flaked layers to any glass
core remaining beneath and fourth b Passive stabilization
reintroduce transparency to thin Passive stabilization means the control
weathering crusts where the glass shows of the surrounding environment to prevent
slight iridescence further decay The stabilization of the
Paraloid B 72 is an acrylic resin that is a environment is often outside the area of a
good all purpose consolidant It is a conservator s immediately responsibility
colorless durable stable resin with a Tg of He should however be consulted as to
40 C and a refractive index of 1 49 and suitable environment for antiquities and
when applied properly should not should thus be in position to advise upon
appreciably alter the appearance of the the correct conditions and methods of
material to which it has been applied storage and display The prevention of
Horie 1987 Newton 1989 Cronyn 1990 further damage and decay represents the
and Sease 1994 A diluted solution of minimum type of conservation especially if
paraloid B 72 3 dissolved in acetone has the reversible techniques are not available at
been applied by a fine spraying technique the time Prevention of decay may only
for each glass object spraying is a very save entail the remove of glass from an
technique and compatible for such fragile unsatisfactory environment Newton
glasses After 24 hours they were 1989
reconsolidated using a concentrated solution According to the research work
of paraloid B 72 5 to emphasis the performed by Al Ahmed and Khasawneh
process of consolidation and act as a 2006 to evaluate and study the
coating film on the glass surface to protect it environmental conditions in the museum of
from the effect of environmental conditions Jordanian heritage they claimed that these
especially the effect of moisture and relative conditions does not completely standard
humidity that raises constantly in the and should be more controlled Their
museum all year long Al Ahmed and measurements found that there are
Khasawneh 2006 constant frequentations in temperature and
5 A301 6 A612 7 A613 8 A00
Figs 5 8 The glass objects after treatment processes the weathered crusts are stabilized chemically and
physically and the visual appearance of iridescence not altered or destroyed
In the present work a scientific
approach for treating corroded glass objects
displayed in the museum of Jordanian
heritage was done This extensive work not
only describes the nature of conservation
process but also provides an ethical
framework to which the conservation of
glass objects as divers as old materials In
addition the implementation of conservation
comprises the technical investigation
stabilization and conservation of glass
objects To be successful it depends on the
conservator knowing what the object is
where it comes from the materials of which
the object is composed the decay
mechanism of those materials and a variety
of measures which could be implemented
to clean stabilize and preserve the object
However conservation of completely
corroded glass represents a complicated
problem many difficulties are facing glass
conservators especially during cleaning
Figs 9 and 10 Showing the current displaying of weathered crusts and treating iridescent
the glass objects in the Museum of Jordanian surfaces as well as stabilizing corrosion
Heritage after treatment reactions This problem was solved here by
carrying out the conservation process in a
balance of three activities investigation all
relative humidity RH throughout the the forms of analysis and examination
year However all weathered glass can be which uncover information about the
stabilized simply by keeping it in a RH of object s composition structure and damage
about 40 per cent above which the process state revelation cleaning and exposing the
of corrosion will be continue Tomson object to reveal its original form and
1987 On the other hand we recommended function and preservation the act of
that these glass objects and all glass seeking to maintain the object in its present
collection in the museum should be form without any further deterioration
displayed together in special displaying This typically involved a full range of
cases and separated from the non glass preventive practices and the stabilization
objects In such state the suitable processes of interventive conservation
environmental conditions required for In all treatment procedures of corroded
preserving this glass collection can be glass objects the visual appearance of
controlled and standardized weathered or iridescent surface a
protective layer or a patina must not be
altered Stabilization can sometimes alter
the visual form of an object e g darkening creating the approach of preventive
of a surface when consolidated or destroying conservation to improve the display system
the visual appearance of iridescence during and preserve the object in a stable and
the chemical treatments There is a balance appropriate conditions
to be struck between gaining a physically
stable robust glass object and the change in ACKNOWLEDGMENTS
visual appearance It can often be helpful to Thanks are due to Mr Wageeh
combine a number of different approaches Ebraheim from Department of Earth
to successfully stabilize corroded glass Sciences in Yarmouk University in Jordan
objects treating the glass object with for carrying out the SEM and EDX
chelating agent EDTA chemically to investigations The author is very grateful to
deactivate the corrosion process all the members of the Museum of
consolidation and coating of the decayed Jordanian Heritage in the same University
surface with acrylic resin Paraloid B 72 for their assistance during documenting and
physically to strengthen the fragile crusts conserving the glass collection
and protecting the weathered surface and
Paraloid B 72 Code 112390 Canada colors and chemicals 80 Scarsdale Road Don Milles Canda
EDTA Disodium ethylendiaminetetraacetic acid Na2 EDTA Sigma product No 4884 Swiss
Company for Chemicals 106 Nile Street Giza Egypt
Abd Alla R 2005 Evaluation of the impact of chelating agent EDTA on the treatment of weathered
glass T Akasheh ed proceeding of The fourth international conference on Science
Technology in Archaeology and Conservation 7 11 December The Hashemite
University El Zarqa Jordan
Abd Alla R 2006 The raw materials of ancient Roman glass in Egypt and Jordan a comparative and
analytical study Adumatu vol 14 23 31
Abd Alla R 2007 Devitrification behavior of corroded glass Four cases study Mediterranean
Archaeology and Archaeometry Vol 7 No 1 1 9
Al Ahmed Z and Al Muheisen Z 1995 A chemical and technological study of Roman glasses
excavated from Yasileh archaeological site Jordan Mu tah vol 11 No 2 5 28
Al Ahmed Z and Khasawneh T 2006 Museum environmental control as a tool for preventive
conservation museum of Jordanian heritage as a case study proceeding of the 13th
international conference for building and construction Inter Build 15 19 June Cairo
Brill RH 1999 Chemical analyses of early glasses 1 Corning museum of glass press New York
Calt S and Spare S 2000 Smear layer removal by EDTA Endodontology vol 26 459 61
Caple C 2003 Conservation skills judgment methods and decision making Rutledge London
Carmela C Donald I 1996 Conservation of glass recovered from shipwreck sites Trinnial
meeting 11th of ICCOM Edinburgh 1 6 September 819 825
Cronyon J 1990 The elements of Archaeological Conservation London
Ernesperger F M 1959 Attack of glass by chelating agents Journal of American Ceramic society vol
42 373 375
Faltermeier R 1998 A corrosion inhibitor test for copper based artifacts Studies in conservation vol
44 121 128
Horie C V 1987 Materials for conservation Butterworth London
Newton R and Davison S 1989 Conservation of glass Butterworth London
Paul A 1978 Influence of complexing agents and nature of the buffer solution on the chemical
durability of glass Part I Theoretical discussion Journal of Glass Technology vol 19
Paul A and Youssefi A 1978b Influence of complexing agents and nature of the buffer solution on
the chemical durability of glass Part 2 EDTA ethyl alcohol and sugar in the leach
solution Journal of Glass Technology vol 19 166 170
Sease C 1994 Conservation manual for the field Archaeologist 3rd edition California
Tomson G 1987 The museum Environment Butterworth London

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