Transcript Challenge of Materials? A new approach to collecting

Challenge of Materials?
Collecting & caring for plastics at the Science
Museum.
Making the most of plastics in you collection.
Scottish National Gallery of Modern Art,
26th November 2007
Fran David, Conservator (Collections Care)
Science Museum
sciencemuseum.org.uk
Introduction
• What lead to this research: The acquisition
scorecard.
• The key plastics and why we want to identify
them.
• The reference fact sheets and how they help.
• The curatorial view.
• Further benefits of this system.
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The Acquisition Scorecard
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Designing a useful reference tool
• What plastics are present?
• How can I go about identifying them?
• Will this plastic deteriorate?
• If deterioration can be seen what does this
mean?
• How can I reflect this in the scorecard?
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Key Problem Plastics
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Cellulose Nitrate
• Deterioration:
– Light and moisture cause
loss of nitrates.
– Water and oxygen then
turn these into acids which
accelerate deterioration
and affect other materials.
– Cracking and crazing can
be caused by the lost of
plasticiser and chemical
breakdown of the polymer.
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Cellulose Acetate
• Deterioration:
– Again releases acidic
products which aid further
decay.
– ‘Vinegar syndrome’
– Ester plasticisers can weep
– Warping is a common
effect of plasticiser loss
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Poly vinyl chloride (PVC)
• Deterioration:
– Light causes discoloration
– Hydrochloric acid can be a
by-product of deterioration
– Plasticisers can migrate to
the surface leading to both:
• Weeping
• Warping
• Cracking
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Polyurethane foam
• Deterioration:
– Oxidation causes
discoloration
– This also causes loss
of strength
– Moisture can also be a
factor
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The Fact Sheets,
3 topics:
• Types of deterioration you might find
• Problem plastics to identify
• How to identify these materials
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Types of deterioration and where you
find it:
• This sheet provides you with the deterioration you might
find on a plastic object and an indication of what plastic
this might be.
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Problem plastics to identify:
• This outlines the 4 key plastics:
–
–
–
–
When they were in production
The types of objects you find made from them
The deterioration you might see
Images to illustrate this
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How do you identify these
materials?
• Here each plastic has a simple yes/no decision tree to
help identify them
• Storage implications are explained
• If additional conservation costs are necessary these are
explained so they can be applied
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Handling
– Always wear gloves when
handling any plastics:
• Not just for the objects safety
but also for your own.
– Know your object:
• Do you know the materials
present?
• How might their properties
have changed?
– Object numbering:
• Either:
– Write directly on the surface
using a fine wax pencil or a
TRIA pen with carbon black
Golden Fluid acrylic paint
only
– Use a water based adhesive
as the intervention layer
after testing that the surface
is not water sensitive
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General
Storage
• Environment:
–
–
–
–
Stability
Temp <20˚C
RH 30-50%
Exclude light
• Support:
– Store and support an
object you know will lose
flexibility in a display
friendly way.
• Isolation:
– Keep objects that may offgas harmful products away
from other materials.
• Filtration
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– Use filtering to reduce
harmful atmospheric
products accelerating
deterioration.
Storage
Specifics
• Cellulose nitrate &
Cellulose acetate:
– Do not wrap
– Isolate from metals and
other materials if possible
– Use air filtration/vapour
scavengers
• Poly vinyl chloride:
– Do not wrap
– Do not store in contact with
expanded polystyrene
– Store with re-display in
mind
• Polyurethane foam:
– Oxygen-free storage
options?
– Store with re-display in
mind
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Display
• Environment:
– Temp & RH:
• <20°C
• 30-50% <5% daily flux
– Light levels:
• No UV
• <150 lux
• Display materials:
– Avoid materials that could
off-gas organic vapours
(wood, MDF etc…)
• Things to avoid:
– Do not put cellulose nitrate
or acetate in a case with
metals or other vulnerable
materials.
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Case studies with Curators
‘ I wouldn’t want to leave a legacy that
somebody’s got to care for. I wouldn’t acquire
something lightly knowing that in 20 years
time somebody’s going to have to spend time
and money looking after it.’
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Forestry raincoat
• The raincoat posed a
number of questions for
the curator:
1. This could not be displayed in
it’s condition so should it be
disposed of?
2. What is the significance of the
object? Does it have a
personal attachment?
3. If not, should another be
acquired if this is going to
happen again?
4. Has there been a change in
importance, from type of
protective coat to technology
of the material?
5. Would this be a reason to
keep this specimen?
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Avoiding problems:
• Try to acquire those
plastics identified as ‘at
risk’ in good condition.
• Store in a way that will
enhance the object’s
useful lifetime.
• Inform all parties about
the potential longer-term
problems.
• Analysis of unidentified
materials should be
budgeted into process.
• Objects acquired for
exhibition which are
identified as having
stability issues should
only be acquired as
auxiliary material so that
it can be disposed of
when the exhibition
closes.
• Objects incorporating
‘smart’ plastics should
only be acquired if we
have been able to get
materials information
from the manufacturer.
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In practice:
Appropriate storage:
Appropriate display:
Accurate care costs with realistic expectations of lifetime & display:
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Conclusions
• The fact sheets are helping us improve our collections care by
increasing our ability to assess unfamiliar materials.
• Because we ask the curators more questions, we get more
detailed material information to plan our treatments and care
on.
• Greater understanding between curator and conservator
when an object is acquired can prevent conflicting opinions in
the future.
• The fact sheets are also helping to inform our storage and
care strategies for objects already within our collections.
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Thanks to:
Sue Mossman
Hazel Newey
Jannicke Langfeldt
The support of the Objects Clinic
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Web Resources
• General care of plastics:
– http://www.conservationregister.com/careplastics.asp?id=4
– http://palimpsest.stanford.edu/waac/wn/wn24/wn24-1/wn24102.html
– http://www.plastiquarian.com/ind6.htm
– http://www.plastiquarian.com/survey/survey.htm (labelling info
not current but otherwise useful)
• Textiles containing plastics:
– http://www.uri.edu/hss/tmd/20th%20Centry%20Plastics.pdf
• Oxygen-free environments:
– http://www.cwaller.de/english.htm?oxygen.htm~information
– http://www.conservation-by-design.co.uk/productlist-oxyfree.html
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