AIC's 41st Annual Meeting

The Herblock foundation donated the entire collection of editorial cartoonist Herbert L. Block (Herblock) to the Library of Congress after he passed away in 2001. The collection included 14,400 original drawings for his daily published cartoons and 50,000 rough sketches. A previous presentation at AIC in 2009 introduced concerns with the collection, since the bequest to the Library required that some of the collection must be on exhibit at all times, and Herblock began using light sensitive materials in the 1970s. Conservators were able to collect a sample of the materials he was using at the time of his death which included porous point pens (felt-tip pens), whiteout, colored pencils, ball point pens, lithocrayons, india ink ,graphite pencils and pressure sensitive labels (Avery labels), as well as a stock of the coquille paper board substrate containing optical brighteners he favored throughout his career. The continuation of this research begun in 2009 encompassed a long-term longitudinal study of the impact of exhibition conditions on contemporary media and substrates. While light exposure on exhibition was an issue, conservators and curators had observed fading of a selection of some of the drawings while in dark storage. To assess changes occurring in Herblock collection materials, and accurately identify the media involved in these changes, sample sheets (Whatman paper and coquille board) of the collected media were created and aged both naturally and with a range of accelerated aging techniques. Aging encompassed both light and dark aging to determine the mode of degradation, with combinations of ultraviolet (UV) and visible, visible light (without UV), moderately raised temperature, relative humidity and dark conditions with sample sheets monitored during carefully controlled natural and accelerated aging. Progressive non-invasive and mildly invasive analyses were undertaken both before and after successive aging periods. Instrumentation included hyperspectral imaging, UV-VIS colorimetry, micro-fade-ometer, and micro-sampling of sample sheets for scanning electron microscopy (SEM). Additional analyses to identify specific components of media shown to have faded or changed in color after various aging methods (such as porous point pens) then underwent separation of ink components with thin layer chromatography (TLC) and analysis with Direct Analysis in Real Time (DART) Time-of-Flight Mass Spectrometry. Additional hyperspectral imaging was undertaken of specific Herblock drawings from the period 1974-2001 that had been either on exhibit or kept in the dark. These drawings all contained the full range of media collected in the sample set. India ink was used as a reference for stability throughout the testing. All the environments where the drawings were located were monitored, and predictive fade testing with the micro-fade-ometer indicated some interesting results for a number of these contemporary materials, with comparisons between the three spectroscopy techniques indicating limitations and benefits in the analytical techniques. SEM EDS confirmed the composition of the optical brightener in the coquille board. The identification of the color change in media and the method of degradation for both exhibit and storage conditions sought to replicate natural aging as closely as possible, and provide long-term useful information for the preservation of this unique collection of modern contemporary materials.