Eric Doehne

Scripps College · Art Conservation

In this paper we propose a reliable surface imaging method for the non-invasive detection of morphological changes in paintings. Usually, the evaluation and quantification of changes and defects results mostly from an optical and subjective assessment, through the comparison of the previous and subsequent state of conservation and by means of condi...

There is a growing realization for a means to assess stony surfaces for microbial growth before it is obvious and visible. The current state-of-the-art technique requires the taking a swab of the structure, and transporting it to the laboratory, and running biochemical or genetic based tests for identifi cation of genus/species. This is a labor-int...

Petra, Angkor, Copan, Venice, Lascaux, Easter Island—all are examples of irreplaceable cultural heritage built in stone and now slowly disappearing. In 1996 the Getty Conservation Institute published Stone Conservation: An Overview of Current Research as a tool for conservators and conservation scientists to guide policy, practice, and research in...

Magnesium sulfate salts have been linked to the decay of stone in the field and in laboratory experiments, but the mechanism of damage is still poorly understood. Thermomechanical analysis shows that expansion of stone contaminated with magnesium sulfate salts occurs during drying, followed by relaxation of the stress during dehydration of the prec...

Micro- and macroscale experiments which document the dynamics of salt damage to porous stone have yielded data which expose weaknesses in earlier interpretations. Previously unexplained differences are found in crystal morphology, crystallization patterns, kinetics and substrate damage when comparing the growth of mirabilite (Na2SO4. 10H2O) and the...

We propose quantifying color in crowd-sourced images from mobile phones to monitor built heritage over time. Time-lapse color movies in CIE color space can provide information on a large range of deterioration mechanisms, including soiling, biofilm growth, weathering and vandalism. Citizen science can create large-scale geographical coverage of sit...

Starting in the 1890s the artist Paul Gauguin (1848-1903) created a series of prints and transfer drawings using techniques that are not entirely understood. To better understand the artist’s production methods, photometric stereo was used to assess the surface shape of a number of these graphic works that are now in the collection of the Art Insti...

In the last decade, imaging has become an increasingly significant player in the analysis, preservation and dissemination of cultural heritage, especially in archeology, art, and conservation programs. As new imaging methods have been developed, they have routinely been applied to cultural heritage. Reflectance transformation imaging (RTI) has been...

Sites and objects of cultural heritage – from art to ancient inscriptions to ruins – are under constant attack by time and the environment. While much is known about how material components change from laboratory-based artificial aging, very little is known about the process or rates of change of actual objects and sites in situ. Reflectance Transf...

Sites and objects of cultural heritage – from modern art to ancient ruins – are under constant attack by time and the environment. They are subject to fading, color loss, material loss, bio-deterioration, soiling and a wide range of other processes. While laboratory-based studies have taught us much about how the material components change, very li...

Sodium sulfates are widely regarded as the most destructive salts for porous stone, concrete and brick. Thenardite (Na2SO4), mirabilite (Na2SO4, 10H2O) and heptahydrate (Na2SO4, 7H2O) are the common phases that occur under surface conditions. The heptahydrate phase has been largely neglected in most modern work about salt weathering. However, sever...

The use of a solar-powered, field time-lapse camera and environmental monitoring system enabled measurements of the pattern and rate of loss of stone from the surface of Howden Minster, an abandoned monastery in Yorkshire dating to 1380 AD. Acquiring a photograph every 1-3 hours allowed the stone damage to be correlated with local environmental cond...

Sodium sulfate is widely regarded as the most damaging salt for porous building materials. To understand this complex and incompletely understood phenomena, it is important to predict which phases will crystallize under a range of environmental conditions and which phase transitions will cause damage. In this study we present data on the crystalliz...

Measuring Change in Art An expert meeting sponsored by the Institute for Advanced Studies, University of Cergy Pontoise, organized by Eric Doehne and hosted by Beatriz Menendez of the GEC, UCP. May 3-5, 2012 Port Cergy, France. Goal: The goal of the meeting is to focus attention on the need for good measurements of how fast works of art are changin...

Evaluating the condition of weathered stone surfaces on a monument, building or sculpture requires information on how those surfaces have evolved. In a number of cases, the documentation related to a site or object is either not readily available or has been lost (due to war, fire, etc.). Exploring the use of geotagged photographs to supplement the...

Dynamic studies allow the observation of microscopical changes of materials over time as various factors alter an object. Using this methodology, processes important in art conservation and archaeology such as the wetting and drying of consolidated and unconsolidated building materials or the corrosion of metals from air pollutants can be studied i...

From Angkor to Zanzibar and Venice to New Orleans, soluble salts are responsible for causing significant damage to porous building materials. But how does salt weathering take place, and what level of salts are harmful? Are certain salts more damaging than others? Should they be removed and if so, how? The use of poultice treatments is well establi...

Report: Poultice Desalination Conclusions--Poultice detachment is a critical parameter and one that is strongly influenced by poultice shrinking and RH The desalination at Madame John’s appears successful (90-98% removal) The commercial poultice tested performed well but had too strong adhesion to weak materials (an new version is now on the market...

Evaluating stone weathering rates and their relationship to environmental fluctuations is an important challenge in understanding the critical zone and also in efforts to prevent the loss of important cultural heritage in stone, such as monuments, sculpture and archaeological sites. Repeat photography has been widely used to evaluate geological pro...

Samples of red and black gloss from Greek Attic pottery of the late sixth to fifth centuries bc were examined using scanning electron microscopy (SEM and FIB/STEM). The focus of the study was the chemical and microstructural characterization of the red gloss that was first produced during this period. Two groupings of red gloss were revealed. One r...

Since its abandonment 185 years ago, the XII century Santa Maria de Bonaval Monastery located in Guadalajara (Spain) has suffered significant deterioration: first the roof was lost, followed by partial collapse of the walls, moisture infiltration and extensive loss of stone surfaces due to salt weathering. This case study is a clear example of the...

Ceramics were the “high technology” material of Ancient Greece, used to produce popular drinking vessels and exotic works of art. This work seeks to characterize these understudied materials using methods such as FIB/STEM, which show promise for the nanoscale sampling and investigation of works of art. Preliminary chemical analyses of samples from...

The rapid deterioration of magnesian limestone buildings in the north of England has been a serious problem for more than one hundred years. While air quality in England has improved during this period, the rate of stone loss in these carved stone structures has not slowed. Thus far, conventional stone conservation treatments have not been successf...

Magnesium sulfate salts often result from the combination of incompatible construction materials that, when combined with a source of moisture, react to form soluble salts often leading to significant damage by flaking of the stone. Several laboratory experiments were performed to reproduce surface flaking on limestone and to evaluate the effects o...

Within the framework of the EU project “Desalination”, Madame John’s Legacy in the French Quarter of New Orleans was selected as a field site to evaluate the effectiveness of four desalination poultices under warm and humid environmental conditions. The poultices were applied to salt-laden brick walls in a sheltered exterior environment and in an a...

Within the framework of the EU project "Desalination", Madame John's Legacy in the French Quarter of New Orleans was selected as a field site to evaluate the effectiveness of four desalination poultices under warm and humid environmental conditions. The poultices were applied to salt-laden brick walls in a sheltered exterior environment and in an a...

The City of Adelaide suffers from rapid damage to historic building materials due to salts, rising damp, and damp-proof course failures. Adelaide City Council has partially funded repairs to over 400 buildings in the past 15years. To begin to examine the scope of this problem and the effectiveness of various treatments, 24 historic buildings in Ade...

Magnesium sulfate salts often result from the combination of incompatible construction materials, such as stone or mortar with high magnesium content and sulfates from adjacent mortars or polluted air. When combined with a source of moisture, these materials react to form soluble salts, often leading to significant damage by flaking of the stone, a...

The ancient Maya combined skills in organic chemistry and mineralogy to create an important technology - the first permanent organic pigment. The unique color and stability of Maya Blue can be explained by a new model where indigo dye fills the grooves present at the surface of palygorskite clay, forming a hydrogen bonded organic/inorganic complex....

The Chapter House at Howden Minster is a small octagonal 14th century magnesian limestone building. The architectural decoration on the interior walls is among the finest of its period in England. The building has been a ruin since the 18 th century, and its elaborate interior stone carving has suffered from ongoing erosion. The deterioration of th...

Constructed entirely of magnesian limestone, the Chapter House at Howden Minster, East Yorkshire, dates from 1380 and has been in the care of English Heritage since 1971. For two hundred and fifty years, it was a roofless ruin; the elaborately carved stone interior subject to significant on-going decay. The acute stone degradation on this site prom...

Time-lapse imaging has been used to provide a record of damage to stone as it is occurring in the field. The site of Howden Minster, UK, where rapid flaking of magnesian limestone has been observed, was used to begin to evaluate the pattern and rate of stone loss, in addition to correlating stone damage with local environmental conditions. Prelimin...

Samples of red and black slips from Greek Attic pottery of the late 6th through 5th centuries B.C. were analyzed by electron microprobe and scanning electron microscopes (SEM and TEM). The focus of the study was the chemical characterization of the red slips that were first produced during this period. By comparing the composition and microstructur...

The application of ESEM technology to the conservation of cultural heritage and other fields is reviewed. Several applications are presented with a focus on reaction kinetics and micro to nano-scale material behaviours, including time-lapse studies of reaction kinetics for NaCl and NaNO3; verification of the stone decay mechanism at the site of Cop...

The behavior and development of thenardite (anhydrous sodium sulfate) from mirabilite (sodium sulfate decahydrate) under the Environmental Scanning Electron Microscope (ESEM) during humidity clycling (50%-100%) was observed. After 7 cycles a microcrystalline porous structure of thenardite was formed with an increased surface area and volume compare...

PDF of Presentation Slides. Supplement to the article: Lopez-Arce, Paula & Doehne, Eric 2006, Kinetics of sodium sulphate efflorescence as observed by humidity cycling with ESEM. Proceedings of the Heritage, Weathering & Conservation Conference, Madrid, Spain, June 2006, HWC. 220-230.

Presentation - PDF of 15 slides.-- Communication presented in: Heritage, Weathering & Conservation Conference (Madrid, June 21-24, 2006). [Background] Fluctuations of atmospheric conditions cause dehydration and hydration of hygroscopic salts, leading to expansion and contraction that results in fatigue stress of the porous material (Overmiller, 19...

Spurious x-ray signals, which previously prevented high-resoln. energy-dispersive x-ray anal. (EDS) in the environmental scanning electron microscope (ESEM), can be cor. using a simple method presented here. As the primary electron beam travels through the gas in the ESEM chamber, a significant fraction of the primary electrons is scattered during...

The SALTeXPERT workshop was structured to include a series of background lectures ranging from a general introduction into the topic of salt weathering, analytical issues, over questions of modeling and mitigation, to the options of direct restorative intervention such as desalination and treatment of salt-laden materials. More than 50 participants...

An Environmental STEM detector was used in the Environmental Scanning Electron Microscope to study the morphology of two types of wet lime putty and to evaluate the fiber size of the ancient pigment known as Maya blue. Environmental Scanning Electron Microscopy (ESEM) is a technique capable of imaging non-conductive materials in their natural state...

Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005.

Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005.

The Hieroglyphic Stairway at Cop·n in northwest Honduras is the longest inscription known from the ancient Maya. As part of a larger conservation project of the Instituto HondureÒo de AntropologÌa e Historia (IHAH) and the Getty Conservation Institute (GCI), blocks of uncarved green and buff volcanic tuff as well as samples of flaking tuff from the...

The Hieroglyphic Stairway at Copan in Northwest Honduras is the longest inscription known from the Ancient Maya. As part of a larger conservation project of the Institute Hondureiio de Antropologia e Historia (IHAH) and the Getty Conservation Institute (GCI), blocks of uncarved green and buff volcanic tuff as well as samples of flaking tuff from th...

Having a controlled environmental chamber with in situ high resolution imaging (i.e. ESEM), has advanced our understanding of important dynamic processes such as corrosion and dissolu- tion/crystallization [1, 2]. However, in order to further advance into the important area of reaction kinetics it is important to begin to better quantify the enviro...

Natural purple pigments are extremely rare. Between 479 BC and 220 AD, a new pigment known as Han Purple was manufactured in China [1]. To aid in the reproduction of this ancient technology, quantitative phase analysis of an octagonal Han Purple color stick was carried out using the electron microprobe. The purple in Han Purple is a Barium Copper S...

In order to better understand stone degradation due to salt weathering, a series of laboratory experiments were performed with NaCl, one of the most common salts in the field. Data from ESEM and optical microscopy experiments show that deliquescence and crystallization of NaCl are strongly influenced by the rate and magnitude of the humidity change...

Salze spielen als Schadensfaktor bei der Zerstörung von Kulturgütern wie Baudenkmälern und Wandmalereien eine große Rolle. In den letzten Jahren wurde mit großem Aufwand versucht, das Kristallisieren der Salze im Porenraum sichtbar zu machen, um die Schadens-Mechanismen aufzuklären. Viele Fragen sind jedoch noch immer unbeantwortet. Ziel der hier g...

Incorporating the results of a meeting held in London in December 2000, sponsored by English Heritage and The Getty Conservation Institute, this article reviews both consolidants and protective treatments for the conservation o f deteriorated limestone and lime plaster. Carbonate deposition (including both inorganic solutions and bio-mineralization...

The effects of [Fe(CN)6]4− ions on the crystallization of NaCl in aqueous solution has been studied, particularly in the situation where the saline fluid percolates through and evaporates from a saturated porous body (i.e., an ornamental porous limestone). In concentrations ranging from 2.48×10−4 up to 2.85 10−3 M the additive was able to increase...

Crystallization modifiers can significantly affect the capillary passage of dilute and concentrated solutions of sodium chloride and sodium sulfate through columns of limestone. In the absence of modifiers, sodium chloride passage through Monks Park limestone gave predominantly subflorescence with mild edge erosion while sodium sulfate mainly efflo...

Why is sodium sulfate so damaging to porous building materials? This question has remained unanswered for at least 170 years, since sodium sulfate began to be used to test the relative durability of different stones (de Thury 1828; Luquer 1895). Two important areas of recent research on this topic are 1) the non-equilibrium crystallization of thena...

The past decade has seen a growing scientific interest in the still poorly understood subject of salt weathering, a phenomenon with significant cultural and economic consequences. This interest has led to an increase in research results and growing clarification of the roles salts play in weathering and decay. The development of improved mitigation...

"In time, and with water, everything changes." ---Leonardo da Vinci The crystallization of soluble salts in porous building materials is a widespread weathering process that re- sults in damage to important monuments and archaeo- logical sites [1]. Salt weathering by thenardite (sodium sulfate) and mirabilite (sodium sulfate decahydrate) is especia...

Introduction : “In time, and with water, everything changes.” —Leonardo da Vinci The crystallization of soluble salts in porous building materials is a widespread weathering process that results in damage to important monuments and archaeological sites. Salt weathering by thenardite (sodium sulfate) and mirabilite (sodium sulfate decahydrate) is es...

Charge contrast imaging (CCI) is a useful new method for imaging sub-micron features in crystalline materials using the unique gas/ion/electron imaging system of the environmental scanning electron microscope (Griffin, 1997; Doehne, 1998). Crystal growth zoning, microfractures, solution boundaries, and areas of chemical alteration or recrystallizat...

The fundamental behavior of sodium sulfate crystallization and induced decay in concrete and other building materials is still poorly understood, resulting in some misinterpretation and controversy. We experimentally show that under real world conditions, both thenardite (Na2SO4) and mirabilite (Na2SO4·10H2O) precipitate directly from a saturated s...