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Conservation Physics - Index |
Workshop on energy efficient museum buildings. There are still a few places available on this course in October 2010.
Requiem for the Cologne City Archive The collapse in 2009 of the archive raises the question: do buildings have to be massive to provide a stable indoor climate without air conditioning? March 2010.
Fundamental microclimate concepts A compact introduction to the units and concepts underlying the environmental physics relevant to museum conservation. September 2009.
Humidity buffer capacity of selected building materials (pdf 2.4Mb) About the moisture buffering properties of unfired brick, and other readily available building materials. We present a new way of quantitatively describing the buffer performance of a wall. September 2009.
Lecture to the British Film Institute about cooling film for preservation, and how to build a cold store. June 2009
Do standard temperatures need to be constant? - Paper submitted to the Going Green conference at the British Museum, April 2009
Using 'awk' to manipulate data files - an agile alternative to excel for editing and merging climate data files. April 2009
Lecture on archive environmental standards - given to the meeting of CEN at the British Standards Institution, London, March 2009 (pdf, 4Mb).
Plotting climate data with gnuplot - an agile alternative to excel. January 2009
Our environmental standards need reform. This page, and associated articles discuss the disadvantages of blindly advocating "Best available technology" for climate control in archives and museums. March 2008
Simple climate control in archives. (2.7Mb) February 2008
Museum Microclimates. Index to all the conference contributions, November 2007
Why keep climate records - and how to keep them May 2007 (pdf 1Mb)
The potential and limits for passive air conditioning of museums, stores and archives April 2007 (4.5Mb)
| Introduction |
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Introduction to this compendium of articles on preventive conservation and building physics applied to historic materials and structures. |
| How to keep for a while what you want to keep for ever |
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A light hearted introduction to preventive conservation |
| Calculator for atmospheric moisture |
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A calculator for deriving moisture concentrations in air from dew point and psychrometer data |
| Fundamental microclimate concepts |
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An introduction to concepts and units concerning heat, moisture and light, which affect the interior environment. |
| The effect of light on museum objects |
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The effect of light on museum objects with particular attention to colours |
| The Candela - unit of luminous intensity |
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An explanation of the fundamental SI unit for light intensity, from which all other luminous units can be derived. |
| The light-fastness of the natural dyes |
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Information on the light-fastness of natural dyes is reviewed. New tests on the fastness of several dyes in fluorescent lamp light are reported.
Nearly all natural dyes have a light-fastness below BS grade 5. Most have a fastness below 4. Nearly all natural dyes will fade badly during an exposure to 50 million lux hours of artificial light, or to a much smaller dose of daylight. In many museum displays serious fading of most dyes would occur in less than fifty years.
There is no very effective way of reducing the rate of fading. Ultraviolet absorbers over light sources give a worthwhile increase in light-fastness to most, but not all, dyes. Low relative humidity reduces fading. Display in cases filled with an 'inert' gas benefits most dyes but accelerates the fading of some pigments used on fabrics. Valuable textiles whose dyes have a light-fastness below 6 should not be permanently displayed. |
| Using a camera as a lux meter |
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How to use a camera as a lux meter, particularly for estimating lux within an inaccessible showcase. |
| The lux is a poor predictor of photochemical damage |
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The lux gives great weight to light at about 550 nm, which is far from the most damaging radiation at about 400nm |
| The Deterioration of Cellulose in light and UV |
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This is a review of research on the deterioration of cellulose through exposure to light, ultraviolet and high energy radiation. The literature coverage stops at 1969, but the radiation sensitivity of cellulose was by then adequately researched because of the widespread use of cellulosic fabrics in aircraft construction before 1930. |
| The absorption of water by materials |
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The sorption isotherm describes the reversible absorption of water by materials exposed to a changing relative humidity |
| Humidity exchange with absorbent materials |
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The exchange of moisture between materials and air |
| The reaction of wood to changing climate |
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The sorption of water by wood and its effects on the physical dimensions of wood. |
| The Preservation Index and the Time Weighted Preservation Index |
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An explanation of the science behind the Image Permanence Institute's Preservation Index and Time Weighted Preservation Index |
| Bending the evidence |
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Permanent set in wood caused by unsymmetrical moisture stress |
| What happens to water absorbent materials below zero degrees? |
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The behaviour of water in moisture absorbent materials at low temperatures. The concept of freezing does not apply when the equilibrium RH is moderate. |
| Stress, strain and craquelure |
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A description of the concepts of stress and strain with particular application to paintings on canvas. |
| The art robbery at Skamkloster |
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A story which illustrates the efflorescence of inorganic salts as the relative humidity fluctuates |
| Humidity buffering by porous, absorbent insulation |
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The influence on the room climate of moisture absorbent insulation in the exterior walls of houses |
| The Mollier diagram and the Psychrometric Chart |
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An explanation of the construction principles of the Mollier diagram and its almost identical alternative - the psychrometric chart. |
| Mechanical air conditioning |
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The principles of mechanical air conditioning in large buildings |
| The breath of Arrhenius: air conditioning in photographic archives |
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The air conditioning needed for film archives, analysed in relation to Arrhenius plots of the rate of deterioration. |
| Condensation in the walls of humidified buildings |
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Examples of museum buildings which have suffered condensation in the structure caused by leakage of humidified indoor air through the outer walls and roof. |
| Humidity buffering by museum walls |
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A review of the process of water exchange between room to wall |
| Humidity buffering by absorbent materials in walls |
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A review of the moisture buffering performance of construction materials. |
| Requiem for the Cologne City Archive |
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The idea that a massive building gives a good archive climate is not as clear cut as one might think. |
| Humidity buffering by clay walls |
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How to use absorbent materials in walls to buffer the relative humidity in archives and stores. |
| Casting mud in the debate on museum environmental standards |
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A suitable choice of building materials would give museums a stable climate without air conditioning. |
| Designing museums with a naturally stable climate |
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A review of trends in modern museum architecture which reduce the natural stability of the indoor climate but paradoxically increase the possibility for stabilising it without massive air conditioning installations. |
| The role of absorbent materials in moderating changes of relative humidity |
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A phd thesis on moisture buffering by construction materials. Chapters on the fundamentals of the interchange of moisture between air and materials |
| The influence of building techniques on the indoor climate |
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A review of the influence of building construction techniques and materials on the inner climate, with a section on biological growth in houses. |
| The climate of Gundsoemagle Church |
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Humidity buffering by porous walls has a considerable moderating influence on the indoor climate. |
| Climate control in the archive of the Arnemagnaean Institute |
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Semi passive relative humidity control by mixing heat flow from the outside and heat from the building interior |
| Does a standard temperature need to be constant? |
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Several articles and publications challenging the strictness of temperature standards for museums and archives. |
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Low energy climate control for museum stores |
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An examination of five control strategies for controlling the temperature and relative humidity in stores containing an abundance of moisture absorbent materials. |
| How to design climatically stable museums |
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Illustrations of the interaction of the local climate with a building without mechanical air conditioning. |
| Designing a Museum Store |
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An analysis of the north European climate and of the preservation requirements of typical museum objects suggests a suitable low energy method of air conditioning a museum store designed to hold relatively durable materials: outside air is sucked in when its water vapour content is unusually low while the temperature is raised slightly to give a relative humidity not far below the limit for biological growth. This combination gives a low degradation rate for both objects and the building that encloses them. |
| Buffering relative humidity within a temperature gradient |
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There is a large risk of condensation when cooling or warming happens quickly. The thermal inertia of materials generates large temperature differences over small distances which can cause acute condensation. |
| Evidence from thin air |
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A story about the effect of changing air pressure on the relative humidity around goods in transit |
| The second Seismograph of Chang Heng |
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On the difference between heat flow into an enclosure and the temperature which it reaches |
| A Himalayan Legend |
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A Himalayan legend describes the surprising consequences of moisture movement caused by temperature gradients in small enclosures. |
| The Hunt Ball |
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A glimpse into the microclimatic mysteries of glass cases. |
| How to protect glazed pictures from climatic insult |
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The climate in a glazed picture frame is surprisingly violently affected by exposure on an outer wall or to direct sunlight indoors. |
| A humidification chamber for relaxing works of art |
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The working principles of a humidity chamber for moistening art without risking condensation |
| Trouble in Store - indoor air pollution |
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As air pollution in cities diminishes, or at least changes its nature, the air pollution generated within buildings becomes a relatively more serious cause of deterioration. The low rainfall indoors allows hygroscopic salts to develop and remain, without ever being washed away. Nearly airtight enclosure brings the threat of damage by modern materials outgassing into the air around museum objects, as well as chemicals given off by self-destructive objects. The commonest indoor pollutants are acid gases from the decomposition of wood, cellulose acetate and cellulose nitrate. Acid attack requires a thin watery film on the surface of the object to allow ionic processes to occur. Within showcases, there is competition between absorption on the object, absorption on a sacrificial absorber and ventilation out through imperfections in the seal.
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| Air exchange between an enclosure and its surroundings |
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An explanation of the exponential progress of air exchange with a nearly sealed container |
| Control of RH and air pollution in showcases |
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The effect of absorbent materials and restricted air exchange on the course of the RH in showcases and picture frames.
This is a digital version of Studies in Conservation 11 (1966) 2-30. |
| The physics of drying cloth |
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Heat and ventilation are both necessary to drying. An experiment shows the relative importance of these two influences and how to dry without over drying to equilibrium with a low relative humidity |
| A small cold store for film |
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A warmed container set within a standard chest freezer maintains a moderate RH at about -5 C
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| Registration for the workshop on energy efficient museum buildings |
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Registration form for the course in museum design, October 2010 |
| Edit course applications |
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Page for editing registrations for courses (password protected) |
| Climate behind the pictures in Ledreborg chapel |
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The climate behind the oil paintings mounted on the outer walls of the Baroque chapel of Ledreborg house in Denmark is surprisingly benign, compared with the climate in the chapel. |
| Database query |
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Query form for the cfys database (password protected) |
| The spontaneous transfer to glass of an image of Joan of Arc |
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A woven silk picture transferred its image to the glass against which it had been pressed for fourteen years. The image was formed from salt, which occupied the areas where the silk had not touched the glass. Salt impregnation increases the water absorption of silk at a relative humidity below the value at which pure salt deliquesces. A salt solution had formed in the fabric at a moderate relative humidity and then migrated to the glass where the salt precipitated because the relative humidity was below the deliquescence point of pure salt. The process has been replicated. |
| The interaction of water vapour with paper in small spaces |
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The interaction of water vapour with paper, with particular reference to humidity buffering of leaky spaces where the kinetics of water movement through paper is significant. |
| SQL language help |
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SQL language help and examples (password protected) |
| Measuring stress and strain |
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Measuring stress and strain in the context of conservation and building physics. |
| Saturated salt solutions for controlling relative humidity |
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The theory and practice of using saturated salt solutions to define a relative humidity for sensor calibration or for treatment. |
| A climate chamber that measures the moisture buffer capacity of materials |
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A description of a climate chamber designed to measure the moisture absorption and release by materials and constructions exposed to a changing moisture flux. |
| Data loggers for climate measurement |
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Data loggers for climate measurements, with hints on how to choose and use sensors. |
| UV detector for museum use |
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An instrument is described which allows the eye to detect sources of ultraviolet radiation. Coincident ultraviolet and visible images of the scene are viewed through an eyepiece. The suspected source of radiation is centered in the field of view. The visible image is then extinguished by operating a shutter. Ultraviolet radiation is revealed by yellow-green fluorescence from a small target in the centre of the field. |
| The thermocouple |
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The thermocouple: how it works and how to use it. |
| Manipulating and plotting climate data |
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How to use awk and other unix utility programs to convert and merge climate data files ready for plotting with gnuplot |
| Writing for the web without being an IT expert |
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Writing technical literature on the web - a discussion of the possibilities for authors without much knowledge of information technology. |
| Publications by Tim Padfield |
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List of publications by Tim Padfield |
Sustainable climate management strategies. A workshop organised by the Getty Conservation Institute on Tenerife in April 2007
Passive design,mechanical systems and doing nothing: a telephone discussion about environmental management. in the Getty Conservation Institute newsletter 22.1, Spring 2007
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The wiki is also used for course announcements and compendia.
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All articles in this Conservation Physics compendium, except the external links, are licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Unported License.