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The Effect of Ultraviolet Radiation on the Microspectrophotometry (MSP) of Dyed Fibers

NCJ Number
255669
Date Published
October 2020
Length
19 pages
Author(s)
Gary J. Laughlin
Agencies
NIJ-Sponsored
Annotation
This is the Final Summary Overview of the findings and methodology of a research project that assessed the effect of ultraviolet (UV) radiation over time on the color of various types of dyed fibers and determined whether any observed change was predictable for a given colorant, using UV-Vis microspectrophotometry (MSP), which is an instrumental analysis technique used in most forensic science laboratories to compare the color of microscopic particles viewed through a microscope.
Abstract
MSP data collected in this research were used to compare control (unexposed to UV), artificial UV-exposed, and sunlight-exposed fibers and fabrics. A total of 53 swatches from a variety of fiber types and dyes of commercial and custom-dyed manufactured fibers that were exposed to artificial UV radiation in the laboratory (Chicago) and sunlight (Arizona) for 18 months were measured with MSP to determine the fading effect of UV radiation on color. Preceding the detection of spectral alteration, the potential effect of instrument-induced photobleaching over time was assessed by continuously exposing each of the dyed fibers to the MSP light sources from 0 to about 3,700 seconds, with a spectrum collected every 60 seconds. The photobleaching study observed spectral alterations in all but one sample. It is important to use a UV blocking filter between all spectra collections and when no active data acquisition is being conducted. Differences in spectral curves obtained at different exposure times were observed for all the samples. The week when spectral alterations were first observed was recorded. Appended figures and tables

Date Created: December 1, 2020