Bảo tàng lịch sử Quốc gia

Preface

This book has a double purpose, and so is divided into two parts. The first part is intended as a textbook for conservators and curators of museums concerning the damaging effects on exhibits of light, humidity and air pollution, and what to do to minimize this damage. The scientific background needed for this first part is kept to a minimun. The second part is meant for workers in the field of conservation research and summaries information which up to now has been widely scattered and sometimes difficult of access. I assume in the second part some familiarity with basic science.

Since the timely publication of the first two editions of The Museum Environment in hardcover, interest in preventive conservation has continued to grow strongly making publication of this paperback edition all the more welcome.

Those whose responsibility it is to care for the valuable and beautiful objects in the world’s collections have become increasingly aware that it is better to prevent their deterioration, by ensuring that they are housed and displayed in the best possible environmental conditions, than to wait until restoration and repair are necessary.

The book is in two parts. Part I, intended for conservators and museum curators, describes the principles and techniques of controlling the environment so that the potentially damaging effects of light, humidity and air pollution on museum exhibits may be minimised. In Part II, the author brings together and summarises information and data, hitherto widely scattered in the literature of diverse fields, which is essential to workers in conservation research.

The changes for the second edition have been mainly concentrated in the sections on electronic hygrometry, new fluorescent lamps, buffered cases, air conditioning systems, data logging, and control with historic buildings. A new Appendix giving a summary of museum specifications for conservation provides a useful quick reference.

The book includes the following contents:

Light Part I

Surface deterioration

Light and heat energy

The spectrum

The basic light sources

Colours and materials which change

Damage caused by UV and visible radiation

UV radiation and how to deal with it

Measuring UV and visible radiation

Reducing illuminance

50 lux – artificial light

Diffusion of light

200 lux – daylight and artificial light

Conservation lighting specifications

Treatment of windows

Angle at which light falls on exhibits

Reducing time of exposure

A suite of exhibition rooms

Heat

Control of temperature

Lighting for professional photography, television and restoration

Electronic flash

Colour rendering

The measurement of colour

The lighting situation and the process of seeing

Humidity Part I

The importance of humidity

Measuring the humidity in the air

The wet-and-dry-bulb hygrometer

Electronic hygrometers

Non-mechanical hygrometers

Understanding the hygrometric chart

Response of museum material to RH

Best RH for moisture-containing absorbent materials

Climate inside and outside the museum

Condensation and the dew point

Humidity control

RH control in a room

The humidistat

Humidifying equipment

Dehumidifying equipment

Room RH control: maintenance and air circulation

Packaged air-conditioning units

Ducted air conditioning

RH control in a closed case – buffers

Silicagel in packing cases

Exhibition cases

The buffered case: towards a practical solution

RH control in a closed case – use of salts

Mechanical RH stabilisation in cases

Future development of exhibition case stabilisation

RH is often a matter of compromise

Historic buildings closed in witer and churches

Improvisation and RH control

Humidity control in archaeology

Air Pollution Part I

The problem

Particulates

Particulate concentrations today

New concrete buildings

Removal of particulates

Electrostatic precipitators (electro-filters)

Gaseous pollution

Sulphur dioxide (SO₂)

Damage caused by sulphur dioxide

Glass and sulphur dioxide

Effects of sulphur dioxide on lichens and mosses

Ozone

Effects of ozone

Nitrogen oxides

Effects of nitrogen dioxide

Levels of ozone and nitrogen dioxide likely to be encountered

Chlorides

Pollution through storage conditions

Removal of gaseous pollutants

Fire extinguishers

Sound and vibration

Light Part II

Spectral curves

Sun and sky

Lamps and control equipment

Measuring UV

Luminous efficiency and the light meter

Some basic light units

Visual performance

Luminance and subjective brightness

The Blue Wool standards

Damage versus wavelength

Heat radiated from light sources

Activation energy

The primary photochemical reaction

Placing a colour on the CIE Chromaticity Chart

The clour rendering calculation

Colour rendering and the black body convention

Choosing a fluorescent lamp

Dimming

Humidity Part II

The standard hygrometric (psychrometric) chart

The classical air-conditioning operation

A museum air-conditioning system

Control

Heating and cooling loads

Sensors

External design conditions

Dimensional changes caused by RH variation

Outdoor climate and response of objects indoors

Does constant RH keep dimensions unchanged at all temperatures?

Effect of people on RH and temperature

Use of the air moisture-content scale

The closed and buffered museum case

Hygrometric half-time

Materials useful as buffers

Penetration of oxygen and water vapour through plastic films

Air Pollution Part II

Plotting the size distribution of particulates

Choice of particulate filter

Efficiency of activated carbon filters

Room air cleaners

Measuring concentrations of pollutants in museums

The fate of sulphur dioxide in the atmosphere

The formation of ozone

Computers in environment control

Data logging

The Library of the Vietnam National Museum of History (No. 25 Tong Dan Street, Hoan Kiem District, Hanoi) would like to present to readers!

Mai An