PREVENTIVE CONSERVATION Amber Xavier-Rowe*

English Heritage
London, UK
amber.xavier-rowe@english-heritage.org.uk
Claire Fry
English Heritage
London, UK
claire.fry@english-heritage.org.uk
*Author for correspondence
Heritage collections
at risk – English
heritage collections
risk and condition
audit

Keywords: risk assessment, condition Introduction

audit, heritage collections, risk factors,
preventive conservation This paper describes how the methodology and data from the English
Heritage collections risk and condition audit has been used to fundamentally
Abstract change planning, priorities, policy and funding distribution for the care
The Collections Conservation team at English and conservation of collections kept in 115 historic houses, museums,
Heritage has completed a national risk assess- churches and stores across England.
ment and condition audit for collections held
in 115 properties. The audit methodology
integrates collection condition, risk assess- Background
ment and collection significance to define
and rank preventive actions across multiple English Heritage (EH) is the UK government’s statutory advisor on the
sites. Display and storage conditions followed historic environment for England. One of its key roles is the conservation
by dust, dirt and handling and then incorrect and presentation of over 400 properties.
humidity are the risk factors that scored the
highest. Evidence from the audit has resulted For the past five years (2004 to 2009) the Collections Conservation team
in a change in collections conservation priori- at EH has been gathering data relating to the condition, significance and
ties, policy and funding distribution and has
been instrumental in raising the importance
risks affecting collections housed in 115 properties and stores. 12,977
of preventive conservation. objects were examined from an estimated total of 480,800, representing
2.7 percent of the national collection.
Résumé
L’équipe chargée de la conservation des col- Audit methodology
lections d’English Heritage a mené un audit
national sur l’évaluation des risques et l’état The audit methodology integrates collection condition, site-based risk
des collections conservées dans 115 sites. La assessment and collection significance to define and rank preventive actions
méthodologie de l’audit incluait l’état des col- across a range of sites. It combines damage evidence provided by a condition
lections, l’évaluation des risques et la valeur
audit and risk levels provided by a risk assessment (Figure 1).
de la collection, afin de définir et de classer
les actions préventives sur de nombreux si- It has been shown by Taylor (2005) that the condition of the collection
tes. Les facteurs de risques qui ont obtenu
le pointage le plus élevé sont les conditions
has a role to play in assessing which risk factors are resulting in damage.
d’exposition et d’entreposage, suivis de l’em- “Corroboration between a risk assessment and condition survey indicates
poussièrement, l’encrassement et la manipu- both exposure and consequence of risk” (Taylor 2005, 138). This concept
lation, et enfin de taux d’humidité impropres. provided the theoretical underpinning for the audit.
Les conclusions de l’audit ont entraîné une
modification des priorités de conservation- The condition audit and risk assessment used a common set of risk factors
restauration des collections, des politiques
(Table 1). These were adapted from risks to museum collections developed
et de la répartition des financements. Enfin,
il a permis de démontrer l’importance de la by others, namely Michalski’s agents of deterioration (1990) and Waller’s
conservation préventive. risk types (1994). The EH list of risk factors relate to the preventive
conservation systems and activities designed to be delivered to site staff
(Xavier-Rowe 2008), the intention being that the risks highlighted for a
particular site could be mitigated through delivering pre-existing systems

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Heritage May_ 2011
collections
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PREVENTIVE CONSERVATION heritage collections
risk and
condition audit
Figure 1. Collections risk and condition audit methodology

Resumen
El equipo para la Conservación de Coleccio-
Identify locations Site inspection
nes de English Heritage completó una eva- Object count Questionnaire
luación nacional de riesgos y una auditoría Random selection Discussion
del estado de conservación de las colecciones
de 115 propiedades. La metodología de la
auditoría integra el estado de conservación Object Condition Audit Risk Assessment
de las colecciones, la evaluación de riesgos 2% [store] 5% [historic
y la relevancia de las colecciones para definir house/museum]
y priorizar las acciones preventivas en múl-
tiples sitios. Las condiciones de exposición
Identify recent Identify cause of Quantify threat Identify
y almacenamiento, seguidas por el polvo, la damage by damage from from each risk collections care
suciedad y el manejo de los objetos, y niveles material list of damage factor solution and
de humedad incorrectos, son los factores de factors cost
riesgo que tuvieron la máxima puntuación.
Las evidencias de la auditoría han dado lugar Damage score Risk Score
a un cambio de prioridades en la conserva-
ción de las colecciones, así como en las polí-
ticas y la distribución de los fondos, y ha sido
fundamental para incrementar la importancia
de la conservación preventiva. Weighted Score
Percentage of Significance
collection at
Ranks actions for a single of collection
location site

Priority Score
Ranks actions across
many sites

Figure 1
Collections risk and condition audit methodology

of care and training programmes (Fry 2007). There was also a pragmatic
decision taken to limit the number of risks to facilitate faster and more
focused site surveys and reports.

The same experienced consultant conservators completed each site audit

alongside EH conservators to ensure a reasonable degree of consistency
was established.

Condition audit

A random sample of objects from each site collection was examined (5

percent for a mixed historic house or museum collection and 2 percent for
a store of similar materials). Pre-defined damage types were recorded for
each material component of an object. The cause of the damage was then
identified from the standard list of risk factors (Table 1). Only recent damage
caused by the present display or storage conditions was recorded.

For each damage type noted, the necessary preventive and/or remedial
treatment was specified with the estimated time to complete the work.
A significance grade was given where A is of international significance;
B, national; C, regional; D, replica; and E, to dispose. A condition score

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Table 1
Risk factors

Risk Factors Examples

Dust, dirt and handling Dust on an object due to insufficient conservation housekeeping; physical
damage due to inappropriate handling, such as chips, scratches or losses
Light Fading of dyes and paints, embrittlement
Incorrect Humidity Cracks, splits, distortion due to low and fluctuating relative humidity (RH);
corrosion, mould growth due to high RH
Pests Damage and soiling due to insect pests, birds, rodents and bats
Display/Storage conditions Tarnishing of silver due to inappropriate display case materials; crushing due
to overcrowding in storage; Abrasion caused by an inappropriate support
Documentation Incomplete or missing documentation, no identifying number marked
on an object. A lack of documentation for some objects, e.g. archaeology
or natural history specimens can mean a loss of research value. This can
be both symptomatic of poor collection care and may result in further
neglect
Disasters & Security Fire, flood, theft or vandalism
Inherent Deterioration. Some materials deteriorate due largely to their composition rather than the
conditions in which they are kept. Examples include photographic film and
plastic

from 1 to 4 was also assigned where score 1, is very good – no signs of

damage; 2, good – slight signs of damage; 3, poor – significant damage;
and 4, very poor – severe damage.

In order to quantify the level of damage to a collection from a risk factor,

a damage score was generated using the following equation

where DS is the Damage Score, as a percent; NU is the number of units

audited showing damage from the risk factor; FS is the fraction susceptible,
the number of units audited that are vulnerable to that risk.

For a site with 1000 units, if 500 units were susceptible to light, then FS
would be 0.5.

Risk assessment

The site-based risk assessment was structured around the same eight risk
factors used in the condition audit (Table 1). A questionnaire completed
by a representative of the site operation team was used to assess whether
a particular collections care system was in place. If a system has been
implemented and maintained, the potential of a risk factor causing damage
is largely reduced. However, if a risk question receives a ‘no’ indicating
a collections care system is not in place, then the recommended solution
and cost is recorded. This information along with observations from the
auditors is fed into the site risk assessment.

The level of risk to a collection was measured by the risk score. This was
achieved by defining and then multiplying the probability of the risk factor

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occurring (P) by the quantity of the collection at risk (Q) by the loss of
display or research value (LV). Therefore the risk score is

RS = P Q LV

where RS is the risk score as a percent; P is the probability of the risk factor
occurring: 1–3years 100%, 4–10 years 30%, 11–30 years 10%, 31–100
years 3%; Q is the quantity of the collection at risk: few 10%, some 30%,
most 70%, all 100%; LV is the loss of display or research value: major
loss of utility 90%, significant loss 50%, minor loss 10%.

Weighted score

In order to rank the eight risk factors at a single property and, therefore, the
associated preventive actions, the damage and risk scores were combined
in different ratios to give the weighted score as follows:

where WS is the weighted score, 0–1; a is the weighting factor for the
damage score and depends on the damage factor; b is the weighting factor
for the risk score and depends on the risk factor.

The weighting of the damage score (DS) and risk score (RS) allowed for
the evidence not seen in the objects examined to be considered. For the
risk factor disasters and security, which occurs rarely but with catastrophic
damage, 100% weighting was applied to the RS. For pests and display/
storage conditions the damage is sporadic and severe; however, the evidence
in the collection is not always immediately apparent. Therefore, in the
above equation, the weighting is higher for the RS, a=33 and b=66. For
the remaining risk factors the damage is constant and mild and evident in
the condition of the collection. For these risks the DS and FS are evenly
weighted.

Priority score

To enable us to prioritise preventive measures territory wide as seen in

Table 2, the site risk assessment embodied in the weighted score is corrected
for the size and significance of the property’s collection in relation to the
total collection in care.

where P is the percentage of objects at that location; S is the significance

weighting where 2=international, 1=national, 0.5=regional.

A priority score of 1 and below was judged to be a low risk. A score from
1.1 to 35, a medium risk, whilst a score of 35 and above was judged to be
a high risk. This grading was based on comparing a selection of known

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high and low risks against the priority scores. Further testing of this
classification is required.

In Table 2, the highest risk at Audley End is dust, dirt and handling, which
has a priority score of 35.15. This score was arrived at as follows:

EH Collection by Category

4% 1%
9% 55%
Archaeology
Books and Archive
RS = P Q LV
Decorative Arts
Social History 10% = 100% × 100% × 10%
Natural History
Fine Art - 0.9%
30%
Ethnography - 0.05%

Figure 2
English Heritage collections by category

P is 50.22, as Audley End showrooms contain 16,047 objects from a total

of 31,951 objects in the east territory.

Data processing

The condition audit and risk assessment data was entered into a custom
designed Microsoft Access database. The database generated the risk and
damage scores and the weighted and priority scores were calculated in
Microsoft Excel.

Results

Facts about EH collections

Not all the objects are accessioned, so the audit data has provided new
understanding to inform both collections management and collections care
priorities. It has determined that the total number of objects is in the region
of 480,800 and that they are located in 115 sites. Over 50 percent of the
collection is made up of archaeological objects followed by books and
archives at 30 percent, decorative arts 8.7 percent and social and industrial
history at 4.2 percent (Figure 2). An unexpected statistic is that the majority
of EH collections (87 percent or approximately 419,096 objects) are kept
for their research and display value in 44 store locations.

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Table 2
East territory risk and condition audit – collections care plan (first 10 out of 15 actions for 2010/11)

Priority Property No. of Significance of Risk/ Priority Solution Estimated Lead Progress Comments
Order Objects Collection Damage score Cost
Factor 20% 50% 100%
1 Audley End 16047 A - International Dust/Dirt/ 35.15 Increase CCA £10,000 Senior
Showrooms Handling hours Conservator
2 Audley End 16047 A - International Light 17.56 Continue UV film £2,500 Conservator/
Showrooms replacement Estates
Review light plan Conservator
Refresh training Conservator
for site staff
3 Beeston 4078 A - International Display/ 11.70 Re-pack £13,000 Conservator Re-packing has
Store Storage collections /Curator started as part of
Conditions the store move
4 Audley End 16047 A - International Disasters & 9.03 Finish Emergency Emergency Emergency Plans
Showrooms Security Plan Manager are now covered
Update salvage £2,500 Emergency by IEPs. Budget
equipment Manager for salvage store
still required
5 Audley End 16047 A - International Humidity 5.67 Continue £2,500 Conservator
Showrooms replacement of
humidistat’s
6 Audley End 16047 A - International Display 5.63 Improve Conservator No longer
Showrooms Storage protection of applicable
Conditions collection during following end of
hospitality events hospitality events
at this site
7 Audley End 5494 B - National Dust/Dirt/ 5.15 Modify
Storerooms Handling housekeeping
plan
Increase CCA
hours as above
8 Audley End 16047 A - International Pests 3.64 Sweep chimneys £500 Conservator/
Showrooms Estates
9 Beeston 4078 A - International Dust/Dirt/ 2.30 STORE CLOSING
Store Handling
10 Audley End 5494 B - National Display/ 1.94 Re-pack £1000 Conservator
Storerooms Storage collection
Conditions

Risks to EH Collections

A national perspective of the risks that have or will cause damage to EH

collections was achieved through using the weighted score. This was
done by simply adding up the weighted score given for each risk factor
at each of the 115 sites.

Display and storage conditions, closely followed by dust, dirt and handling,
are the two highest risks to EH collections. Incorrect humidity, in third
place, also appears to be a concern, as does the disasters and security risk
factor. The risks related to pests and light scored low, mainly because
the systems of care including insect pest monitoring and light prevention
methods are well established. Inherent deterioration also scored low,
reflecting the small number of inherently unstable materials in the EH
collection and their relatively young age. Lack of documentation recorded
a low overall score as well.

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Analysing the object condition data gathered from over 12,977 objects
provided an insight to which materials are the most vulnerable. The
materials in poorest condition were ferrous metal, closely followed by
wood, then paint (oil, acrylic/alkyd, etc.), non-ferrous metal, and paper
(Table 3). Incorrect humidity and storage and display conditions were
the most common cause of damage. This information has refocused the
collections conservation research plan towards understanding the tolerances
of archaeological iron, bronze and veneered furniture to relative humidity
in order to develop practical mitigation methods.

Table 3
Materials in poorest condition

Material Number of times scored Most common cause of damage

condition 3 or 4 1
Metal, ferrous 115 Incorrect humidity [56%]
Wood 88 Display/storage conditions [40%]
Paint (oil, acrylic, alkyd etc) 7 Display/storage conditions & Dust/dirt/
handling, both [34%]
Metal, non ferrous 61 Display/storage conditions & humidity,
both [36%]
Paper 52 Display/storage [48%]

Condition score 3: poor – significant damage

1

Condition score 4: very poor – severe damage

Costs relating to preventive and remedial conservation could also be

estimated from the audit data. As part of the risk assessment, when mitigation
systems were not in place, then a solution was suggested and an estimated
cost entered into the database. It was therefore possible to predict that
£400,000 needs to be invested in ongoing preventive conservation activities.
This amount could be further broken down by territory and by the type
of mitigation measure, e.g. insect pest monitoring, packing and support,
housekeeping equipment and materials, monitoring equipment and analysis,
ultraviolet-absorbing window film replacement, and training.

The condition audit data from examining 2.7 percent of the collection
provides an indication of the investment required in remedial conservation
treatment. The total investment required in the conservation treatment of
objects of international and national significance is in the region of £2.3
million or £230,000 each year for ten years.

National priorities arising from the audit results

For the first time, EH has an objective steer on the risks to the collections
in its care. This information will direct priorities relating to collections
conservation for the next ten years.

Display and storage conditions represent the greatest risk to EH collections.

Collections conservation expertise, effort and funds need to be directed
towards mitigating these risks, working alongside the curators who manage
the stores. Packing and environmental issues are starting to be addressed
as part of an ongoing stores consolidation programme. Knowing that many

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of the most pressing issues are with the stores and not exhibitions, as
previously thought, has redirected the collections conservation research plan
to address environmental control, storage of archaeological iron, bronze,
bone, archives and reburial of stone. Materials and methods for repacking
small finds have been revised to ensure that damage from organic volatile
compounds and relative humidity is reduced. The potential for developing
volunteer capacity to assist with repacking campaigns and the replacement
of silica gel in thousands of plastic boxes is under development.

EH showcases standards have been transformed over the past five years
following research into optimising showcase design. The collections
conservators supported by the conservation scientist are now responsible
for technical design, commissioning, installation and air exchange testing.
However, showcases installed prior to 2005 are causing damage. Where
possible, a programme of retrofitting or replacement to improve conditions
is underway.

Damage is also being caused to collections from dust, dirt and inappropriate
handling by staff and visitors resulting in soiled objects, chips and scratches.
Keeping collections and historic interiors free of dust, dirt and knocks
across 115 sites remains a challenge. Not only will dust bond to surfaces
if it is not regularly removed, but the visual presentation of the site is
compromised. The objective evidence from the audit has encouraged a
new discussion with the department that operates the sites to address
an issue that affects both the collections and the quality of the visit. A
number of solutions and ideas have been proposed, including: conservation
housekeeping schedules published in site operation manuals; annual site-
based training days; employment of contract cleaners to vacuum floors
and dust robust flat surfaces; and setting up local volunteer teams to help
clean the collections.

Incorrect humidity is the third highest risk factor. The monitoring and
analysis of internal environmental conditions remains a priority. However,

National Risks to EH Collections

6000

5000
Weighted scores

4000

3000

2000

1000

0
Dust/Dirt/Handling
Light
Documentation

Humidity
Deterioration

Display/ Storage

Disasters &
Pests

Security
Inherent

Conditions

Risk Factor

Figure 3
National risks to English Heritage collections

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the management of a dispersed monitoring programme is time consuming.

The collections conservators are being trained and supported to undertake
the annual analysis of site data, which can then be used to inform control
strategies. In our London properties, which are opened all year round, a
more radical approach relating to heating in winter is required. It has been
proposed that the heating thermostats should be set at 19°C to help prevent
excessively low relative humidities. Lower winter temperatures will also
slow down insect pest activity and reduce the energy bill. Practicalities
relating to visitor and staff comfort could be overcome through zoned
heating and the wearing of appropriate clothing.

The risk level relating to disasters and security was used to highlight
the lack of emergency planning at EH sites, which led to the setting up
of a central Integrated Emergency Planning (IEP) team. This dedicated
resource has resulted in a step change both in the design and delivery of
site emergency plans. The Surviving Emergencies Course, based on a
course developed by the Collections Conservation team, and now run in
partnership with the National Trust and the Department of Culture, Media
and Sport Emergency Planning and Training Group, further supports
implementation of site disaster plans.

The remaining risk factors are considered to be less of a concern as long

as the established systems and procedures are maintained relating to
integrated emergency planning, documentation, pests, light and inherent
deterioration.

Communicating the evidence

The evidence provided by the audit can only become influential through
how it is communicated. In a large multifaceted organisation like EH,
which employs almost 2000 staff, senior management and a range of
disciplines and colleagues at all levels need to be informed of the benefits
of preventive conservation relating to collections.

To attract the attention and support of senior management, including

the chief executive, the State of EH Collections Report was prepared
(Xavier‑Rowe 2010). This report both highlighted facts and figures about
the condition and risks to EH collections and also outlined realistic national
priorities and solutions delivered by adjusting the way existing resources
are targeted. Its purpose was to be a stand-alone factual and objective report
to which covering papers could be attached to target different audiences.
The report was taken to the EH executive board and successfully raised the
profile of collections care through a covering paper which recommended
a more integrated approach between visitor operations, estate maintenance
and collections conservation.

The national programme relating to property development and maintenance

is controlled by a property steering group made up of directors from visitor
operations, estates and properties presentation. The state of collections
report was taken to this group with a covering paper which raised two

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key recommendations: the first being that a series of building-related

preventive conservation measures (e.g. cleaning of chimneys, fitting
of ultraviolet absorbing window film, adjustments to heating systems)
should be funded from the national property maintenance programme; the
second recommendation was that the conservation cleaning of interiors and
collections should be recognised as an essential visitor operation responsibility
supported by the collections conservation team. Both recommendations
were endorsed in principal by this senior management group.

English Heritage properties are divided up into six territories. Property

maintenance and development for each group of territory sites is managed
by a panel of representatives from visitor operations, estates and properties
presentation departments. Territory collections risk and condition audit reports
were prepared using the audit data. These became the key communication
and management tool for both raising the risks affecting the collections
and prioritising preventive actions to mitigate the risks (Table 2). Each
territory audit report was taken to this panel by the head of collections
conservation and the territory-based collections conservator. A covering
paper highlighted annual building-related preventive measures for funding
from the property maintenance programme.

Site-based audit reports including an action plan were prepared for all
115 sites with collections. These were presented to site team meetings by
the collections conservator.

Prior to the communication campaign described above, recognition of

EH collections and the resource required to care for them was low. EH
priorities relating to its property portfolio are on increasing commercial
income and the conservation and maintenance of the built estate. The
successful integration of collections care into this dynamic is proving
to have a major effect on the establishment of preventive conservation
measures.

Existing preventive conservation budgets held by the collections curators

and collections conservation teams are now prioritised from a national and
territory perspective using the prioritised territory action plans (Table 2).

Increasingly remedial treatment programmes are to be informed by condition

surveys of vulnerable collections categories including easel paintings and
gilded furniture. Condition surveys now identify the cause of damage using
the same risk factors used in the national audit providing further evidence
for preventive measures required at particular properties.

The audit methodology has also had a wider impact on EH and Her Majesties
Revenue and Customs (HMRC) policy towards the care of inheritance
tax exempt collections retained in privately owned historic houses across
England. EH monitors the condition of these collections on behalf of
HMRC and has recently promoted risk-based preventive conservation. This
policy is in the process of being promoted as best practice through an EH
publication titled Historic House Collections: Drawing up a Collections
Management Plan (Xavier-Rowe 2010).
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Conclusion

The logistics of caring for a dispersed collection combined with an

ambitious programme of improving the presentation of EH properties
places considerable pressure on limited resources. Combining risk, condition
and significance information into an audit of English Heritage collections
has provided a mechanism for prioritising time and funds on a local,
regional and national scale. The results have fundamentally changed the
way resources are allocated for collections care at EH and established the
importance of preventive conservation across the organisation.

Acknowledgements

The authors are indebted to Dr Joel Taylor, whose Ph.D. research (‘An
examination of the validity and reliability of collection condition surveys’,
Cardiff University 2009) underpins the audit methodology, and to Halahan
Associates (Frances Halahan and Jennifer Dinsmore) for their contribution
to the methodology and for undertaking the site surveys with members of
the Collections Conservation team.

References

Fry, C., A. Xavier-Rowe, F. Halahan, and J. Dinsmore. 2007. What’s

causing the damage? The use of a combined solution-based risk assessment and condition
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107–114. Copenhagen: National Museum of Denmark, Hvidovre.
Michalski, S. 1990. An overall framework for preventive conservation and remedial
conservation. In ICOM-CC 9th Triennial Meeting Preprints, Dresden, 26–31 August 1990,
ed. K. Grimstad. 589–591. London: International Council of Museums.
Taylor, J. 2005. An integrated approach to risk assessments and condition surveys.
Journal of the American Institute of Conservation 44: 127–141.
Waller, R. 1994. Conservation risk assessment: a strategy for managing resources
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and Access, eds. D. Saunders, J. Townsend and S. Woodcock, 186–191. London: The
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Xavier-Rowe, A., and C. Fry. 2010. State of English Heritage Collections Report,
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