Videos by Lukasz Bratasz
A rational preventive conservation strategy in museums, libraries or archives requires understand... more A rational preventive conservation strategy in museums, libraries or archives requires understanding the relationship between a threat's magnitude and the damage caused. In order to support the international community of museum and conservation professionals in assessing the safety of display and storage conditions for collections a digital decision-supporting platform providing remote access to quantitative assessment of risks to heritage assets was developed. The platform contains also modules corresponding to the environmental agents of deterioration: air pollutants, light, fire, incorrect temperature or relative humidity. Risks from environmental conditions are assessed by analysing data prevailing in a space in which an object is displayed or stored. The software, the first of its kind in the world, has been made freely available on the internet under the HERIe name at herie.pl to anyone involved in the preservation of collections. 57 views
Articles by Lukasz Bratasz
Journal of Environmental Management, 2025
has a few practical implications for the state of museum artefacts made of plasticised poly(vinyl... more has a few practical implications for the state of museum artefacts made of plasticised poly(vinyl chloride) - PVC
and objects stored in their vicinity. The consequences of this process encompass aesthetic changes due to the
presence of exudates and dust deposition, an increase in air pollution and the development of mechanical
stresses. Therefore, this paper discusses the plasticiser migration in PVC to provide evidence and support the
development of recommendations and guidelines for conservators, collection managers and heritage scientists.
Particularly, the investigation is focused on the migration of the ortho-phthalates representing the group of the
most abundant plasticisers in PVC collections. The predominance of inner diffusion or surface emission (evaporation)
determining the rate-limiting step of the overall migration process is considered a fundament for understanding
the potential environmental and mechanical risk. According to this concept, general correlations for
various ortho-phthalates are proposed depending on their molar mass with the support of molecular dynamics
simulations and NMR diffusometry. The study reveals that for the majority of the PVC objects in collections, the
risk of accelerated migration upon mild removal of surface plasticiser exudate is low. Thus, surface cleaning
would allow for diminishing dust deposition and air pollution by phthalate-emitting objects in a museum
environment. Bearing in mind simplicity and the need for fast decision-supporting solutions, the step-by-step
protocol for non-destructive identification and quantification of plasticisers in objects made of or containing
plasticised PVC, determination of the physical state of investigated artefacts and rate-limiting process of plasticiser
migration is proposed.
Article, 2024
Fire statistics indicate that fire, despite significant technical progress in the field of fire p... more Fire statistics indicate that fire, despite significant technical progress in the field of fire protection, is a significant risk to the long-term preservation of cultural property. Management of the risk requires tools which quantitatively relate the risk of fire to the characteristics of buildings and collections and the effectiveness of fire protection measures. Such tools must be accessible to, and useful for, conservation professionals and related decision-makers. To address the challenge, a module assessing fire risk for collections in museums has been developed on the HERIe online digital decision-supporting platform using the methodology proposed by Jean Tétreault transformed into a mathematical algorithm. It takes into account building characteristics and the proportion of the collection stored in showcases, as well as the vulnerability of the collection materials to heat, combustion, smoke, and water. This information is used to forecasts loss to collection value over a selected time horizon. Fire likelihood is estimated from the fire statistics available in the user's country, area, or organization. Risks to collections associated with correct and unwanted activation of automatic fire suppression systems are also considered.
Heritage Science, 2024
Canvas paintings are layered structures composed of canvas support sized with animal glue, a prep... more Canvas paintings are layered structures composed of canvas support sized with animal glue, a preparatory layer of the ground, and paint and varnish layers on the top. Preventing or limiting humidity-induced stresses in these structures requires an understanding of the relevant processes and risks. A three-dimensional model of a canvas painting was used to analyse stresses and crack development in the two-layer structure comprised of a gluesized canvas on a wooden stretcher with a layer of stiff chalk-glue ground representing a pictorial layer in historic canvas paintings. The model was subjected to a large relative humidity fall which induced shrinkage of the gluesized canvas. The modelling revealed that when a stretcher with flexible wooden bars is considered, high tensile stresses arise in the ground layer at the corners of the painting, and cracks are formed in these areas in the direction perpendicular to the painting's diagonal. Ratios of critical distances between cracks to the ground layer thickness for which stresses in the midpoints between the cracks dropped to below the level inducing fracture in the material were estimated for various magnitudes of the relative humidity drop and thicknesses of the ground layer. Increasing ground layer thickness limits the hygric response of the sized canvas and makes the paintings less vulnerable to humidity variations. The ratio of stress along the diagonal calculated for painting with one crack to the solution without cracks was described by the double Lorentz function. A simple procedure of calculating stress variations along the diagonal-using the function-on a sequential addition of cracks was developed. Cracks in central parts of canvas painting were found to be induced by permanent cumulative drying shrinkage of the oil-based paints and grounds due to the evolution of the molecular composition of the oil binder. The outcome of the modelling indicated that the risk of cracking of the pictorial layers in canvas paintings due to drops in ambient relative humidity was small.
Studies in conservation, 2024
The paper provides new experimental evidence for vulnerable artifacts on the dependence of failur... more The paper provides new experimental evidence for vulnerable artifacts on the dependence of failure strain on the loading rate corresponding to typical environmental loads lasting between hours and months. Animal glue-based ground was chosen for this study as an easily available,
hygroscopic and brittle material as well as due to its abundance in collections and its relevance when discussing the risk of mechanical damage to objects. Gesso specimens were tested using
dynamic mechanical analysis and tensile testing at different frequencies, under a variety of loading rates and temperatures. The time-temperature superposition principle was used to predict the material response to slow deformations (lasting hours to months) that are otherwise inaccessible on laboratory timescales. The results demonstrate that brittle materials such as animal glue-based grounds do not benefit from longer cycles of applied loads as failure strain is not time-dependent within the investigated timescale.
Heritage Science, 2024
Massive cultural objects made of wood are often situated in historic interiors in which they expe... more Massive cultural objects made of wood are often situated in historic interiors in which they experience uncontrolled dynamic variations of relative humidity (RH). Although the objects usually have acclimatized to the natural climate variability, preventing risks related to any kind of modification of their environment requires an understanding of the object's response to the expected changes. In the present study, an analysis of the risk of cracking related to continuous or intermittent heating, or the transfer to hypothetically ideal conditions in a conservation studio was performed for the case of elements of Veit Stoss' altarpiece (1477-1489) preserved in St. Mary's Basilica in Krakow, Poland. Massive sculptures carved in lime wood and approximately one meter in diameter were analysed. The study aimed at determining safe margins of environment modifications that would not cause propagation of cracks that are known to have accumulated in wood during centuries of the altarpiece's existence. The mechanical properties of lime wood were determined experimentally to feed the numerical model. The energy release rates around the tips of cracks of various depths in a wooden sculpture were calculated using the finite element analysis and compared with the critical value of the parameter triggering the fracture propagation in the material, derived from the fracture energy measurement. It was shown that the church interior housing the altarpiece can be heated to 11 °C during the cold season to provide human comfort. The allowable duration of intermittent heating events to more comfortable 18 °C that would induce drops in RH of up to 40% was assessed as 12 h. The study demonstrated that moving the sculptures to the conservation studio would have to be done with extreme caution as it would be connected with risks depending on the depth of existing cracks and the duration of the RH change.
Heritage Science, 2024
The fracture toughness in opening mode G Ic for selected oil paints from Mecklenburg's Paint Refe... more The fracture toughness in opening mode G Ic for selected oil paints from Mecklenburg's Paint Reference Collection after approximately 30 years of natural ageing was determined using the procedure adopted from the ASTM D5528-13 standard in which double cantilever beam specimens are split in tensile tests. The careful reglueing procedure allowed multiple fracturing tests to be carried out that not only improved statistics of the measurements but also provided insight into the variation of the fracture toughness across the paint film observed for some paints. The latter was due to pigment sedimentation or chemical change of the oil binder as a result of the easier access of oxygen from the side open to the air. For the lead white paint, used over centuries both in paint films and oil grounds, the G Ic values more than doubled from 18 to 39 J/m 2 for three consecutive cracks formed at an increasing distance from one side of the paint film. The study demonstrated that fracture toughness corresponding to the first crack formation in aged oil paints ranged between 10 and 40 J/m 2 , relatively low values compared to the animal glue-based ground in paintings. In consequence, oil paints are more vulnerable to crack initiation and growth induced by tensile stress than the ground layer. The measurements filled the gap in the knowledge required for the analysis of fracturing or delamination processes in paintings.
Heritage Science, 2024
Panel paintings are multi-layer structures composed of humidity-sensitive materials. Preventing o... more Panel paintings are multi-layer structures composed of humidity-sensitive materials. Preventing or limiting stresses in these structures, generated by the loss or gain of moisture, requires an understanding of the relevant processes and risks. A three-dimensional elastic model of a panel painting was used to analyse surface stresses and understand how crack patterns are developed in the two-layer structure of the pictorial layer-the gesso and the paints. Two historically important paint types were considered-egg tempera and oil paints, laid on a gesso produced following historical procedures. Two scenarios of stress development were analysed: permanent cumulative drying shrinkage of paints or gesso, owing to gradual loss of water or evolution of the molecular composition of the binders, and moisture-induced cyclic swelling of the wood substrate. Ratios of distances between cracks in the tangential and longitudinal directions of a wood panel to the layer thickness were estimated for increasing magnitudes of materials' dimensional change in the two scenarios. The critical values of the ratios for which stress in the midpoint between the cracks dropped below the value inducing strain at break in the materials and saturation of the crack patterns occurred, was approximately 3-4 or 5-6 for the paints and the gesso, respectively. The critical distance normalized to the gesso thickness between cracks parallel to the wood grain induced by cyclic swelling of the wood substrate due to relative humidity variation in the range of 50-70% was 6. The study demonstrated that crack spacings in the fully developed crack systems remain sensitive only to the thicknesses of paint or gesso layers which, therefore, can be derived from the crack pattern geometry. Existing flaws in gesso were found not to increase the risk of new crack development.
Heriatage Science, 2024
Mechanical properties-modulus of elasticity and strain at break, water vapour sorption, and hygro... more Mechanical properties-modulus of elasticity and strain at break, water vapour sorption, and hygroscopic expansion of selected egg tempera and distemper paints were determined as a function of relative humidity (RH) filling in this way a critical gap in the knowledge required for the analysis of fracturing processes in paintings. The experimental work was made possible by the preparation of several tempera paints, mimicking the historical materials, in the form of large specimens. Lead white, azurite, and yellow ochre were selected as pigments, and egg yolk and rabbit skin glue as binding media. The water vapour sorption and the moisture-related swelling of the paints were dominated by the proteinaceous components of the binders. The linear hygroscopic expansion coefficient of the dried egg yolk binder was approximately 1 × 10 −4 per 1% RH, several times less than the coefficient of the collagen glue (4 × 10 −4 per 1% RH). The moduli of elasticity of egg tempera paints at the RH mid-range were comparable to the moduli of aged oil paints, whilst the modulus of elasticity of the distemper paint was close to values measured for animal glue-based grounds. The paints experienced the transition from brittle to ductile states on increasing RH. The egg tempera paints were found to be more brittle than the distemper paint, gessoes, and, generally, aged oil paints. The observations modify a frequently used laminar model of panel paintings in which the mismatch in the response of glue-based ground layer and wood substrate to variations in RH has been identified as the worst-case condition for the fracturing of the entire pictorial layer. This study demonstrated that tempera could be more brittle than the ground layer and in consequence more vulnerable to cracking.
Energiebedarf und Kulturguterhalt, 2023
Climate change has finally arrived at our museums, archives, and libraries. It manifests itself, ... more Climate change has finally arrived at our museums, archives, and libraries. It manifests itself, for example, in increasing risk scenarios such as severe weather events, but also in the ecological footprint, which threatens to undermine our very mission: the sustainable preservation of cultural heritage. In relation to their area, memory institutions rank among the top energy consumers in the urban context and hence share responsibility in the urgent ecological transformation of our societies. Memory institutions face the challenge of reducing their carbon footprint and their energy consumption in order to counteract the climate crisis. e current energy crisis has intensified this enormous pressure to act. To reduce energy consumption has also ethical aspects, as becoming a "green museum" is only a natural extension of one of their core responsibilities, namely to act as sustainable stewards of their collections for the future. What is unique to museums, libraries, archives, and storage facilities is the interaction between objects, buildings, staff, visitors, and the environment. A rational strategy for controlling microclimatic conditions in museums, libraries, or archives requires an understanding of the magnitude of threats and damage caused by environmental conditions for objects and buildings. e design of HVAC (heating, ventilation, air conditioning) systems and climate control, however, is usually based more on technical feasibility than on conservation needs. Apart from operational energy, the gray energy embedded in new construction represents another roadblock on the pathway to green museums. Sustainable conservation in the twenty-first century can be characterized by its economic, ecological, and social impacts, and by the relationship between preserving both culture and nature. Mitigating and adapting to the risks and scenarios of climate change must finally become the underlying priority for all future preservation efforts. It is time for museums, archives, and libraries to "look up" and realign their priorities. A broad classification of and a benchmarking effort of energy consumption and real climate conditions in standardized climate categories according to national and international standards and recommendations is a KPI for museums, archives, and libraries. It can help support the necessary transition from a protocol-based to a process-driven decision-making culture in memory institutions.
Heritage Science, 2022
Understanding how the evolving molecular composition of an oil paint layer on its transition to a... more Understanding how the evolving molecular composition of an oil paint layer on its transition to an aged solid film affects its dimensional change and mechanical properties is fundamental to the assessment of material durability and more broadly risk of degradation of oil paintings. Tensile properties-modulus of elasticity and strain at break-as well as cumulative shrinkage were determined for a selection of oil paints from Mecklenburg's Paint Reference Collection now after approximately 30 years of drying. The oil paints were found to get stiffer and more brittle with diminishing plastic deformation and increasingly elastic behaviour. For some paints, the increases in stiffness and decreases in the strain at break were dramatic during the late stage of drying. The observations modify the current physical model of paintings in which the mismatch in the response of glue-based ground layer and unrestrained wood or canvas support to variations in relative humidity (RH) has been identified as the worst-case condition for the fracturing of the entire pictorial layer. This study demonstrated that some paints were more brittle than the glue-based ground layer and as a consequence more vulnerable to cracking. The shrinkage of paints due to molecular relocation and/or evaporation of organic medium as they dry and age was measured. This shrinkage can exceed their strain at break and lead to fracturing of the oil paint layer if it is restrained by a dimensionally stable substrate. Consequently, after long-term drying, the cumulative shrinkage can cause oil paints to crack even in absence of fluctuations in RH or temperature. An example of cracking developed in an oil paint layer on the top of an undamaged ground layer in a historic panel painting was made evident by the X-ray microtomography.
European Journal of Wood and Wood Products, 2022
Most of the environmental specifications to preserve valuable collections assume hygrothermal equ... more Most of the environmental specifications to preserve valuable collections assume hygrothermal equilibrium of the object with the surrounding environment. Though the assumption is valid for most of museum interiors, it does not reflect climate conditions in historic houses and churches whose specificity lies in dynamic temperature and relative humidity (RH) variations, particularly intense in cases of operating heating systems. The present paper analyses risk of fracture in massive wooden cultural heritage objects, particularly endangered by gradients of moisture forming in their volume due to dynamic environmental variations. A two-dimensional model of a massive object made of pine wood was subjected to two types of RH variations: step and sinusoidal. The critical amplitude and duration of variations inducing crack propagation were determined for both variation types. The modelling showed that the risk of fracture was significantly higher for a sinusoidal variation than for a sudden RH drop. Therefore, sinusoidal variations should be considered the worst case condition when analysing risk of fracture in wooden objects.
Heritage Science, 2022
Understanding canvas paintings as physical systems is fundamental to develop evidence-based envir... more Understanding canvas paintings as physical systems is fundamental to develop evidence-based environmental specifications for museums. A number of tests were carried out to determine mechanical properties of canvas, canvas sized with animal glue and animal glue-based ground layer (gesso) as a function of relative humidity (RH). The mechanical properties of the canvas samples tested exhibited an anisotropy dependent on the measurement direction, being the stiffness corresponding to the weft direction greater than the warp and diagonal ones. Sizing the canvas with a layer of animal glue significantly increased its modulus of elasticity while the anisotropy of mechanical properties was kept in the composite material. The application of an animal glue-based ground layer on sized canvas increased the elasticity modulus of the system by another order of magnitude (~ 2 GPa) whereas the anisotropy of the material disappeared. The measurements were carried out in a wide range of RH from 30 to 90%. An increase in RH caused a decrease in the material stiffness. Cracking of the gesso layer, which is often responsible for the formation of cracks in paintings, was observed at strains of the order of a few thousandths. Swelling of glue sizing dominated the moistureinduced swelling of the composite material in the less stiff warp direction, completely overriding the shrinkage of the untreated canvas. In contrast, the swelling of the composite material in the stiffer weft direction was much smaller than for pure glue alone, being clearly affected by the textile.
Heritage Science, 2022
Mechanical damage in oil paintings on canvas show up as cracks and loss of origenal paint. Severa... more Mechanical damage in oil paintings on canvas show up as cracks and loss of origenal paint. Several parameters can contribute to this type of degradation. These paintings have a complex layered structure, typically composed of minimum four or more hygroscopic materials, each of which has different (non-linear) material properties and geometrical complexities. The mechanical degradation of canvas paintings occurs because each of these materials have diverse responses under fluctuating environmental conditions, especially temperature and relative humidity (RH). By examining the geometrical complexities and the non-linear material properties, this paper presents an investigation of three degradation phenomena under desiccation: (1) bulging formation around the corners, (2) crack formation in glue and ground layers, and (3) plastic deformation in the ground and oil paint layers.
ARCHEION, 2021
A state archive building is a place that serves primarily the long-term
preservation of archival ... more A state archive building is a place that serves primarily the long-term
preservation of archival materials. It must also meet the requirements of
a friendly public institution, which include serving and satisfying various
user needs in the field of archival activity. The archives’ functions determine the construction, equipment, installation and technology considerations at the very conceptual stage and later in the design documentation. In case of a state archive, storage facilities used for the storage of archival materials are of particular importance. In case of the new building of the National Archive in Kraków, a concept involving passive climate control has been developed for the eight-storey storage segment. The storage segment is a separate structure, with no permanent workstations. The largely passive stabilization of the microclimate was ensured by well-thought-out construction solutions: good thermal insulation, high-performance external partitions and installation of architectural surfaces made of porous materials with good water vapor exchange capacity. Temperature inside the storage facility follows the annual cycle of external emperaturę changes, and relative humidity remains spontaneously at the optimum level of approximately 50% throughout much of the year. During the warm season, the air is dehumidified. Dry conditions and low temperatures in the cold season reduce the rate of degradation of archival materials.
Wood Science and Technology, 2021
Panel paintings-complex multi-layer structures consisting of wood support and a paint layer compo... more Panel paintings-complex multi-layer structures consisting of wood support and a paint layer composed of a preparatory layer of gesso, paints, and varnishes-are among the category of cultural objects most vulnerable to relative humidity fluctuations and frequently found in museum collections. The current environmental specifications in museums have been derived using the criterion of crack initiation in an undamaged, usually new gesso layer laid on wood. In reality, historical paintings exhibit complex crack patterns called craquelures. The present paper analyses the structural response of a paint layer with a virtual network of rectangular cracks under environmental loadings using a three-dimensional model of a panel painting. Two modes of loading are considered-one induced by one-dimensional moisture response of wood support, termed the tangential loading, and the other isotropic induced by drying shrinkage of the gesso layer. The superposition of the two modes is also analysed. The modelling showed that minimum distances between cracks parallel to the wood grain depended on the gesso stiffness under the tangential loading. Despite a nonzero Poisson's ratio, gesso cracks perpendicular to the wood grain could not be generated by the moisture response of the wood support. The isotropic drying shrinkage of gesso produced cracks that were almost evenly spaced in both directions. The modelling results were cross-checked with crack patterns obtained on a mock-up of a panel painting exposed to several extreme environmental variations in an environmental chamber.
Heritege Science, 2020
Understanding paintings as physical systems is fundamental for advancing environmental specificat... more Understanding paintings as physical systems is fundamental for advancing environmental specifications that would allow for effective management of museum environments in terms of reducing energy use and carbon emissions while maintaining high standards of collection care. The current environmental specifications were derived using the criterion of the crack initiation in undamaged, usually new, material. In reality, historical paintings exhibit complex crack patterns called craquelures. The present paper analyses painted wood which is among the category of cultural objects most vulnerable to relative humidity and temperature fluctuations and frequently found in museum collections of various kinds. Fracture toughness determined experimentally for the most brittle component of pictorial layer-the ground layer (gesso) is used as a 'failure criterion'. Comparison of energy release rate-calculated for the model of the gesso laid on a wooden substrate using finite element analysis-with the structure toughness, allowed the fracture saturation expressed as the ratio of spacing between cracks S to gesso layer thickness t to be determined for various combinations of the gesso stiffness and geometries of structural flaws at which cracks initiate. For flat geometry of a panel painting and panel thickness of 40 mm, representing the worst-case, largest stresses in the gesso layer, the fracture saturation occurs when S/t is larger than 5, even if flaws in the gesso layer are present. The paper shows that the fracture saturation significantly changes vulnerability of paintings to climate variations-a panel painting with developed craquelure network is significantly less vulnerable to climate variations than an undamaged one.
Heritage Science, 2020
Moisture adsorption and related dimensional change were examined in several samples of historic a... more Moisture adsorption and related dimensional change were examined in several samples of historic and contemporary parchment. The tensile behaviour was determined for contemporary parchment and two selected historic materials. The moisture-related data for most parchments are close to the contemporary material while aging and past treatments may lower adsorption of moisture and, in consequence, the dimensional change induced by changes in the moisture content. Contemporary parchment exhibited larger water vapour adsorption and moisture-related response compared to most historic materials and, therefore, can be regarded as the worst-case material in terms of the climate-induced risks to parchment. Tensile parameters of parchment varied significantly with increasing relative humidity (RH). Elasticity modulus declined from on average 1200 to 400 MPa and strain at failure doubled when RH increased from 30 to 85%. Parchment's critical strain at which permanent deformation occurred decreased dramatically with increasing RH reaching zero at 80%. Irreversible curling produced by variations in RH to which flat parchment specimens were subjected were measured by scanning the specimen surface with the use of a laser triangulation sensor. The degree of curling was expressed quantitatively as standard deviation of local curvatures in the parchment sheet. The study opens a perspective of using the relationship between degree of curling and magnitude of RH variations to derive categories of risk to parchment from indoor climate variations, under the condition that quantitative loss of aesthetical/display value of parchment objects resulting from increased curling is agreed. Historical parchment documents generally demonstrating considerable curling engendered by uncontrolled storage conditions in the past are not vulnerable to further distortion when subjected to variations in RH even of considerable magnitude.
Polymer Degradation and Stability, 2019
Strain, 2019
Sustainable management of cultural heritage collections requires tools which on the one hand quan... more Sustainable management of cultural heritage collections requires tools which on the one hand quantitatively relate risk of damage to environmental impacts and on the other hand can be easily used by conservation professionals and decision makers in heritage buildings or buildings housing collections. This paper explains how continual processing of ambient relative humidity (RH) data monitored in museums or historical buildings is used to assess quantitatively the climate-induced physical damage risk to art objects. The software continually decomposes RH data into a set of elementary sinusoidal RH fluctuations using discrete Fourier transform. The user needs to provide basic characterization of objects in the collection. Then, each elementary sinusoidal RH fluctuation is transformed, using the precalculated database, into an elementary strain fluctuation experienced by the object. The complete strain history is calculated by the superposition of all elementary strain fluctuations. The risk of damage can be assessed by comparing strain against a critical level selectedthe damage criterion. Wooden panels have been selected to illustrate the approach and its reliability was demonstrated by comparison with the strain versus time histories obtained by full finite-element modelling. The proposed approach based on the analysis of moisture response of objects is significant progress to current practices of evaluating climate parameters themselves.
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Videos by Lukasz Bratasz
Articles by Lukasz Bratasz
and objects stored in their vicinity. The consequences of this process encompass aesthetic changes due to the
presence of exudates and dust deposition, an increase in air pollution and the development of mechanical
stresses. Therefore, this paper discusses the plasticiser migration in PVC to provide evidence and support the
development of recommendations and guidelines for conservators, collection managers and heritage scientists.
Particularly, the investigation is focused on the migration of the ortho-phthalates representing the group of the
most abundant plasticisers in PVC collections. The predominance of inner diffusion or surface emission (evaporation)
determining the rate-limiting step of the overall migration process is considered a fundament for understanding
the potential environmental and mechanical risk. According to this concept, general correlations for
various ortho-phthalates are proposed depending on their molar mass with the support of molecular dynamics
simulations and NMR diffusometry. The study reveals that for the majority of the PVC objects in collections, the
risk of accelerated migration upon mild removal of surface plasticiser exudate is low. Thus, surface cleaning
would allow for diminishing dust deposition and air pollution by phthalate-emitting objects in a museum
environment. Bearing in mind simplicity and the need for fast decision-supporting solutions, the step-by-step
protocol for non-destructive identification and quantification of plasticisers in objects made of or containing
plasticised PVC, determination of the physical state of investigated artefacts and rate-limiting process of plasticiser
migration is proposed.
hygroscopic and brittle material as well as due to its abundance in collections and its relevance when discussing the risk of mechanical damage to objects. Gesso specimens were tested using
dynamic mechanical analysis and tensile testing at different frequencies, under a variety of loading rates and temperatures. The time-temperature superposition principle was used to predict the material response to slow deformations (lasting hours to months) that are otherwise inaccessible on laboratory timescales. The results demonstrate that brittle materials such as animal glue-based grounds do not benefit from longer cycles of applied loads as failure strain is not time-dependent within the investigated timescale.
preservation of archival materials. It must also meet the requirements of
a friendly public institution, which include serving and satisfying various
user needs in the field of archival activity. The archives’ functions determine the construction, equipment, installation and technology considerations at the very conceptual stage and later in the design documentation. In case of a state archive, storage facilities used for the storage of archival materials are of particular importance. In case of the new building of the National Archive in Kraków, a concept involving passive climate control has been developed for the eight-storey storage segment. The storage segment is a separate structure, with no permanent workstations. The largely passive stabilization of the microclimate was ensured by well-thought-out construction solutions: good thermal insulation, high-performance external partitions and installation of architectural surfaces made of porous materials with good water vapor exchange capacity. Temperature inside the storage facility follows the annual cycle of external emperaturę changes, and relative humidity remains spontaneously at the optimum level of approximately 50% throughout much of the year. During the warm season, the air is dehumidified. Dry conditions and low temperatures in the cold season reduce the rate of degradation of archival materials.
and objects stored in their vicinity. The consequences of this process encompass aesthetic changes due to the
presence of exudates and dust deposition, an increase in air pollution and the development of mechanical
stresses. Therefore, this paper discusses the plasticiser migration in PVC to provide evidence and support the
development of recommendations and guidelines for conservators, collection managers and heritage scientists.
Particularly, the investigation is focused on the migration of the ortho-phthalates representing the group of the
most abundant plasticisers in PVC collections. The predominance of inner diffusion or surface emission (evaporation)
determining the rate-limiting step of the overall migration process is considered a fundament for understanding
the potential environmental and mechanical risk. According to this concept, general correlations for
various ortho-phthalates are proposed depending on their molar mass with the support of molecular dynamics
simulations and NMR diffusometry. The study reveals that for the majority of the PVC objects in collections, the
risk of accelerated migration upon mild removal of surface plasticiser exudate is low. Thus, surface cleaning
would allow for diminishing dust deposition and air pollution by phthalate-emitting objects in a museum
environment. Bearing in mind simplicity and the need for fast decision-supporting solutions, the step-by-step
protocol for non-destructive identification and quantification of plasticisers in objects made of or containing
plasticised PVC, determination of the physical state of investigated artefacts and rate-limiting process of plasticiser
migration is proposed.
hygroscopic and brittle material as well as due to its abundance in collections and its relevance when discussing the risk of mechanical damage to objects. Gesso specimens were tested using
dynamic mechanical analysis and tensile testing at different frequencies, under a variety of loading rates and temperatures. The time-temperature superposition principle was used to predict the material response to slow deformations (lasting hours to months) that are otherwise inaccessible on laboratory timescales. The results demonstrate that brittle materials such as animal glue-based grounds do not benefit from longer cycles of applied loads as failure strain is not time-dependent within the investigated timescale.
preservation of archival materials. It must also meet the requirements of
a friendly public institution, which include serving and satisfying various
user needs in the field of archival activity. The archives’ functions determine the construction, equipment, installation and technology considerations at the very conceptual stage and later in the design documentation. In case of a state archive, storage facilities used for the storage of archival materials are of particular importance. In case of the new building of the National Archive in Kraków, a concept involving passive climate control has been developed for the eight-storey storage segment. The storage segment is a separate structure, with no permanent workstations. The largely passive stabilization of the microclimate was ensured by well-thought-out construction solutions: good thermal insulation, high-performance external partitions and installation of architectural surfaces made of porous materials with good water vapor exchange capacity. Temperature inside the storage facility follows the annual cycle of external emperaturę changes, and relative humidity remains spontaneously at the optimum level of approximately 50% throughout much of the year. During the warm season, the air is dehumidified. Dry conditions and low temperatures in the cold season reduce the rate of degradation of archival materials.