Background: The Library of Congress has a quality assurance program that tests materials that come into contact with collections in storage or display. These tests assure that storage and display materials will not contaminate collections or cause other harm. The traditional Oddy test assesses the impact of off-gassing on collection items being stored or displayed and is performed by placing the material being tested in a sealed glass vial with metal coupons (copper, lead and silver) and water at 60°C for 28 days. A blank of water and coupons alone, without other materials, is also tested. If the tested material visually appears more corroded or oxidized than the blank, then the material normally fails and is not used in an exhibit. This corrosion information is an indicator of whether the off-gas vapors from the materials will cause chemical degradation of a collection item in the same exhibit case or in storage.
The Oddy test results are subjective because the coupons are visually examined and rated. While preservation materials have traditionally been evaluated using the lead, copper, and silver sensors in the presence of the material being tested, this does not necessarily correlate well to our primarily paper based collection. The Preservation Research and Testing Division is investigating the use of 100% cellulose Whatman filter paper rather than metals as a sensor for materials that may degrade paper-based collections. Multiple analytical methods are being used to assess the degradation level of the paper and the chemicals off-gassing from the preservation material that are either breaking down the Whatman paper or absorbing into it.
An update of the current research at the Library of Congress was given as a TOPS presentation on September 2015.
View webcast (73 minutes - requires Real Player to view).
Contributing Studies:
Green, L and Thickett, D.; “Testing Materials for Use in Storage and Display of An Antiquities – A Revised Method”, Studies in Conservation, 40, (1995), pp. 145-152.
Breitung, E.M., Wiggins, M., “An Oddy Test Alternative for Paper-based Collections”, PITTCON Conference & Expo., Philadelphia, PA, March 2013.
Wiggins, M., Breitung, E.M., “A Paper-based Alternative to the Oddy Test”, American Institute of Conservation 41st Annual Meeting, May 2013, Poster presentation.
Aging of preservation materials in silicone rubber o-ring sealed vials with Whatman No1 paper test strips in a 60 degree Celsius oven.
Extraction of Whatman filter paper’s cellulose degradation products into water.
Project Description: Common book and paper preservation materials such as book cloths, binding boards, foams, and adhesives have been subjected to accelerated aging in the presence of Whatman filter paper and the traditional Oddy test (metal sensors). The papers have been evaluated with ion chromatography (IC) and ultraviolet-visible (UV-Vis) spectroscopy. Metal coupons were assessed with visual observation and x-ray diffraction (XRD). Gel permeation chromatography (GPC) is underway. The results from IC and UV-Vis were compared with the subjective visual evaluation of the metal coupons. Gas chromatography – mass spectrometry (GC-MS) is underway to identify the chemicals observed in the IC. Further studies have been undertaken with x-ray diffraction to assess and identify the corrosion products present on the metal coupons from traditional Oddy testing, in order to better understand the often contradictory results obtained and better inform the conservation community.
Outcome/Findings: The study resulted in the following key findings:
- IC and the traditional Oddy test do not always produce the same results.
Materials that pass the Oddy test do not always pass the IC test. - UV-Vis shows an interesting trend in the ultraviolet wavelengths, where UV-Vis of paper aged in the presence of potential preservation materials that tend to degrade the paper sensor also tend to show more intense absorptions in the ultraviolet spectrum. Research is ongoing, however, UV-Vis may potentially be useful as a rapid pre-screening technique.
- While paper degradation components can be observed using the IC technique, polymeric materials such as adhesives and foams tend to show large amounts of non-paper degradation products. Investigations to identify and characterize both paper and non-paper degradation products are ongoing.
- Correlation of the degree of polymer scission to the IC and UV-Vis results is being investigated using GPC to determine the degree of polymerization of the aged papers.
Acknowledgments: Marcie Wiggins, Aaron Ullman, Bradley Scates
