Research and Technical Studies Specialty Group Talks – Microfading

The RATS talks, organized by Stephanie Porto, included a morning session on microfading, as well as afternoon talks covering a range of topics. Chong Tao and Paul M. Whitmore presented work on developing a new microfading test instrument (MFT) for light exposures that includes near-UV wavelengths. The instrument takes advantage of the effect of chromatic aberration to tune relative intensity and incorporate the 300 – 400 nm range. Using various filters, the authors have successfully tested the new instrument with good correlation to the Suntester microfade instrument.

Jim Druzik and Christel Pesme presented research that characterized the performance characteristics associated with four different instrumental set-ups. They presented data collected from seven instruments where the lens design/light probe method was varied including three bench top instruments (planoconvex, achromat, lens-less) and two portable instruments (planoconvex and lens-less). These instruments test a range of spot-sizes during analysis (0.2 – 0.5 mm). Results were tabulated using three of the CIELAB equations used to calculate color space. Based on their results, the authors are satisfied that portable MFT will return similar results to bench top instruments. Future research will include testing prepared samples in a round robin, while also further altering experimental parameters to include other light sources, as well as testing samples in air/anoxic environments.

Dale Kronkright presented microfade research and a database template for archiving and organizing this information. All work results from microfade research associated with a group of Georgia O’Keeffe watercolors in the Georgia O’Keeffe Museum collections. This work was the result of collaborations with the Getty Conservation Institution and University of Texas El Paso. The selected watercolors were well-documented with limited exhibition histories. The research also tested similar/same artist’s materials found in the artist’s studio – also in the museum’s collections. The authors analyzed all objects to characterize chemical composition using portable XRF and FTIR. In an effort to improve the conservator’s voice and make microfade results useable for curatorial and collections management staff, Kronkright et al. developed an automated database platform in Microsoft Excel to aid curatorial decisions. The database tracks remaining exhibition weeks/loan time available using a graphical fuel gauge in terms of just noticeable difference (JND). Future research will correlate accelerated fade rates with those observed in real time in order to adjust exhibition strategies.

More microfading and other RATS talk summaries coming.