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This presentation presents an overview of polymer coatings for outdoor cultural heritage. The presentation defines cultural heritage, examines deterioration causes, discusses polymer usage for protecting bronze and stone monuments, and offers a look forward. The presentation was created for the Waterborne Symposium, New Orleans, La. March 1-4, 2011.
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Polymer Issues in Conservation and
Preservation of Cultural HeritageBy Mary F. Striegel,
National Center for Preservation Technology and Training
The objects that
make up a
portion of our
cultural heritage
have physical
lives.
Over time, they
respond to their
environments and
break down from
natural or manmade
causes.
NCPTT was created to develop or transfer
new technologies to the world of historic
preservation.
NCPTT works with a variety of partners to
advance preservation techniques.
Without the ability to
develop new
improved coatings for
use with cultural
materials, many of
these treasures will
be lost.
New technologies hold the promise of new
ways to study and conserve our cultural
heritage.
We must engage interdisciplinary teams to
apply new polymer systems can help
preserve cultural objects for future
generations.
What is Cultural Heritage?
KellyMullaney, “Cultural Exhibits during Hispanic Heritage Family Day,” October 21,
2008, online image, flickr.
Architectural
buildings
and structures. . .
Archeological
sites and
collections. . .
Art or historical collections. . .
Parks, gardens and other landscapes can
all be considered cultural heritage.
Cultural Heritage can be internationally
significant or highly personal.
Cultural resources are subjected to many
agents of deterioration.
Natural decay goes
unchecked from
lack of
understanding of
chemical/physical
properties.
Decay is a result of complex factors
that lead to loss of integrity.
Air pollution interacts with stone to produce
weathering products and accelerates decay.
Subsequent rains
wash away the
stone resulting in
a “melting” of
outdoor sculpture.
Metal Corrosion
Moisture and Water
Moisture and Water
Biological Organisms
Grow in an amazing
variety of environments
Micro-organisms can:
– produce corrosive
compounds
– consume compounds
that inhibit corrosion
The presence of biological
organisms almost
always increases
corrosion rates in
metals and deterioration
rates in stone.
Inherent vice
Ethical Considerations
• Do no harm
• Respect and retain
original material
• Minimize impact
• Understand
treatments and
materials used
• Choose stable
materials
Polymers Used in
Conservation
Anti-Corrosion Coatings
Chemical Types
Oils5 Lemon Oil
Paraffin Oil
Castor Oil
Shellac15 Copal Shellac in methylated
spirits
Natural Waxes16 Beeswax
Carnuba Wax
Lacquers5 Cellulose acetate
Agateen (nitrocellulose)
Microcrystalline Waxes17, 18 Synthetic waxes
Polyethylene wax
Brush
Application of a
microcrystalline
wax coating
Chemical Types
Acrylics5, 6, 19-23 Incralac (a methylmethacrylate)
Nikolas 11565 Acrylic Lacquer
Bedacryl 221X
Polyvinyl chloride
Waterborne Acrylic Urethanes6 Nikolas 11650 Eco-borne Brass
Lacquer
StanChem one-part acrylic
urethane
Cape Cod Research, Inc.
polyurethane (2-part system)
Solvent-based urethanes6, 24 Nikolas 9778 Exterior Uralac
PPG’s DelClear® DAU75
Acrylic Urethane
Siloxanes25 Ormacer (an organic-inorganic
copolymer sol-gel)
Spray
Application of
an Incralac
Coating
Stone Consolidants
Types of Stone
Consolidants
Inorganic materials
Organic polymers
Alkoxysilanes
Conversion treatments
Inorganic Materials
Alkali silicates
Calcium hydroxide
Barium hydroxide
Silicofluorides
Organic Polymers
Acrylic
Epoxy
Polyurethane
AlkoxysilanesEthyl silicate (TEOS)
Methyl trimethoxy silane
Methyl triethoxy silane
HCT is a conversion
treatment recently
developed for calcareous
substrates. Treatment
converts calcium
carbonate to a more
stable mineral.
Adhesives
Surface Integrity
Visual Appearance
Retreatability or Reversibility
Viqi French, “Intense,” from Meeting of the Waters,
St. Louis, Mo. February 23, 2011,online image, flickr.
Water Vapor
Permeability
VOC Regulations
Calcareous Stone
Indiana Limestone Vermont Marble
Ideal Polymers…
• Transparent color
• Adds no gloss or sheen
• Applies as a waterborne system
• Stable under a variety of environmental
conditions, including temperature cycling,
and UV exposure and
• Reversible or Retreatable
Current
polymeric
treatments are
inadequate to
protect our
cultural heritage
from decay.
“…the need to build broad based partnerships
between conservation scientists and scientists
from universities, national laboratories, industry
and other institutions...”
CHEMISTRY AND MATERIALS
RESEARCH AT THE INTERFACE
BETWEEN SCIENCE AND ART
Report of a Workshop Cosponsored by the
National Science Foundation and the Andrew W. Mellon Foundation, July 6-7, 2009
Engage interdisciplinary teams to
apply new polymer systems that
can help preserve cultural objects
for future generations.
Create collaboration
and outreach
through
conferences,
publications, and
social media to bring
together new teams
and unique
approaches.
Create Sustained Funding efforts ...
• NSF program
solicitation 11-528
• Full proposals due by
May 11, 2011
• Three year awards
with funding up to
$140,000 per year
• Must have a
recognized
conservation scientist
as part of the team
Act III, Scene 4 – The Resolution
2012
Preservation Technology and Training Grants
• Annual Call for Proposals:
September 2011
• Deadline for Submission
October 15, 2011
• One Year Award Up to
$25,000
• Requires a 1 to 1 match
• Simple online process
• http://www.ncptt.nps.gov/grants
/call-for-proposals-2011/
Polymer scientists can play a crucial role in
preserving our nation’s treasures.