Forensic Fiber Analysis: Advanced Microscopy and Microchemistry (1507)
COURSE OUTLINE & SYLLABUS
Course schedule: 8:00 a.m. – 5:00 p.m. Monday – Thursday, and 8:00 a.m. – 12:00 p.m. Friday
Optical and microchemical methods are used for characterization and identification of natural, regenerated and synthetic fibers.
Proficiency in polarized light microscopy is assumed and necessary. Animal fibers are recognized by their morphology and classified into major groups. Synthetic and regenerated fibers are characterized by polarized light microscopy. Vegetable fibers are characterized by anatomical features. Methods for the collection of fibers are considered and practiced. Students in this course typically include forensic and materials scientists as well as those involved with indoor dust and contaminant identification.
Prerequisite: course 1201 or equivalent
(See courses 1201, 1204 or 1207 for classes that include substantial portions of general fiber characterization as well as the fundamentals of polarized light microscopy.)
• Introduction and overview of forensic fiber microscopy, historical background.
• The animal textile fibers; woody and non-woody vegetable fibers; regenerated and synthetic fibers.
• The structure of fibers in longitudinal view.
• The utilization of stains for chemical identification, contrast and demonstration and mapping of additives and structures.
• The shape and structure of fiber cross-sections.
• Interpretation of cross-sections.
• Modification ratio.
• Techniques for the preparation of cross-sections.
• Correlation of longitudinal appearance and cross-section and determination of denier from single fibers.
The identification of vegetable fibers:
• Concept of the technical fiber and fiber ultimates. Scientific and common names and the importance of authentic reference material.
• Origin of the non-woody vegetable fibers in the plant stem.
• Diagnostic tissues and cells.
• Maceration techniques.
• Optical crystallographic characteristics. Stains.
Optical properties I:
• The color of fibers.
• Normal dyeing, solution dyeing and novel dyestuffs.
• Dichroism and dyeing theory.
• Characterization and comparison of color in fibers from the forensic perspective.
Optical properties II:
• Refractive indices, birefringence and sign of elongation — their determination, origin, and interpretation.
• The use and misuse of compensators. The Standort Diagram.
Optical properties II (continued):
• Techniques for the determination of the principle optical properties of fibers and their use in the identification and comparison of synthetic and regenerated fibers.
• Fiber determinations.
• The thermal behavior of thermoplastic fibers and its use in identification and comparison.
• Technique for determining the melting range of fibers with the microscope hot stage.
• The value of chemical and elemental information in forensic fiber examinations.
• Chemical information from infrared spectra.
• Elemental information form X-ray spectroscopy.
• Classical microchemical techniques.
• Techniques for performing microchemical tests on microscopic lengths of fibers.
• Criteria for fiber comparisons and the interpretation of results.