Article by: Joyce Zucker, Seyfollah Maleki PhD, Erin Moroney, Mary Betlejeski
Nanotechnology and Materials Testing: Using Nanoparticles to Tag Consolidant to Determine Depth of Penetration
The research project and publication Nanotechnology and Materials Testing were developed via a PTT grant funded by the National Center for Preservation Technology and Training.
The mural painted by Robert Winthrop Chanler at Coe Hall, Planting Fields State Park, began deteriorating soon after its completion in the 1920’s. The whimsical mural depicts a Wyoming landscape complete with bison, elk and Native Americans on horseback. Chanler’s unusual use of materials and technique combined with dramatic changes in the room’s environment led to chronic flaking, spalling and loss. Over the decades, multiple attempts have been made to stabilize the mural, unfortunately with limited success.
After the environmental conditions were improved, conservators at Peebles Island Resource Center, New York State Parks, Recreation and Historic Preservation, began reinvestigating treatment methods for the mural. Mock-ups of the mural were used to test a range of consolidation techniques and adhesives. Analyzing the success of the test was impossible because it was difficult to determine, how and well the consolidant had penetrated the mock-up’s structure, otherwise known as depth of penetration.
Various techniques exist to determine depth of penetration, but research has found that these techniques may impede the consolidant’s penetration, require subjective observations, or result in imprecise measurements. To effectively track depth of penetration, the tagging material must be stable, inert, compatible, visible and not impede penetration. Advancements in nanotechnology may have provided a solution.
19th Century plaster tagged with Paraloid B72. The Paraloid B72 was tagged with red fluorescing (620nm) nanoparticles. The image was taken under ultraviolet light (350nm) at 100x magnification.
Nanoparticles are microscopic particles with at least one dimension less than 100 nanometers. A nanometer is equal to one billionth of a meter. Working with scientists from the Physics Department of Union College, Schenectady, NY, conservators began experimenting with nanoparticles to determine depth of penetration. The nanoparticles selected for testing were not only stable and inert, but also displayed an intense visible fluorescence under ultraviolet light.
The technique involves adding a small amount of nanoparticles in solution to a liquid consolidant. The nanoparticles served to “tag” the consolidant enabling the normally invisible consolidant to be seen under ultraviolet light. The tagged consolidant was then applied to the surface of the mock-up. When viewed under ultraviolet light, the tagged consolidant revealed the depth of penetration of the consolidant through the mock-up.
Research to date has indicated that under the right conditions nanoparticles may be used to determine the depth of penetration of a consolidant. Current limitations include incompatibility with some materials due to electrostatic interference and alcohol based materials.
The Many Uses of Nanoparticles – The Nano-scale is fascinating!