Development of Contact Portable Microfade Tester to Assess Light Sensitivity of Collection Items

Abstract

The microfade tester is used to assess fading rates of fugitive colors of collection items. The paper presents the research considerations to design a simple, less expensive and portable contact microfade tester that could serve as a screening tool for conservators. Hardware design for such an instrument is presented that includes variations in light source (xenon or LED) and measuring head (ball lens or angled holder fiber), and does not need refocusing between measurements. Performance of the portable microfade tester versions was tested on lab samples and a paper based collection item and based on the ability to rank light sensitivity relative to that of ISO Blue Wool Standards 1, 2 or 3. The results are compared to the ranking obtained with the bench instrument when testing sensitivity of the same items for the same duration. All versions of the portable hardware were found suitable for use as a screening tool to discriminate light-sensitive collection items, with performance of the portable microfade testers using an LED optimized for samples more fugitive than Blue Wool Standard 3. These portable microfade testers need not replace the bench microfade tester as the presented portable microfade tester versions are only suitable to test collection items tolerating surface contact with the instrument.