OSAC 2022-S-0019 Standard Guide for 

Forensic Examination of Fibers

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OSAC 2022-S-0019

Standard Guide for

Forensic Examination of 

Fibers

Trace Materials Subcommittee

Chemistry: Trace Evidence Scientific Area Committee 

Organization of Scientific Area Committees (OSAC) for Forensic Science
OSAC 2022-S-0019 Standard Guide for 

Forensic Examination of Fibers

2

Draft OSAC Proposed Standard

OSAC 2022-S-0019 Standard Guide 

for Forensic Examination of Fibers

Prepared by 

Trace Materials Subcommittee

Version: 1.0 - OSAC Open Comment

March 2022

Disclaimer:

This OSAC Proposed Standard was written by the Trace Materials Subcommittee of the Organization of 

Scientific Area Committees (OSAC) for Forensic Science following a process that includes an open 

comment period. This Proposed Standard will be submitted to a standards developing organization and is 

subject to change. 

There may be references in an OSAC Proposed Standard to other publications under development by 

OSAC. The information in the Proposed Standard, and underlying concepts and methodologies, may be 

used by the forensic-science community before the completion of such companion publications.

Any identification of commercial equipment, instruments, or materials in the Proposed Standard is not a 

recommendation or endorsement by the U.S. Government and does not imply that the equipment, 

instruments, or materials are necessarily the best available for the purpose.

To be placed on the OSAC Registry, certain types of standards first must be reviewed by a Scientific and 

Technical Review Panel (STRP). The STRP process is vital to OSAC’s mission of generating and 

recognizing scientifically sound standards for producing and interpreting forensic science results. The 

STRP shall provide critical and knowledgeable reviews of draft standards or of proposed revisions of 

standards previously published by standards developing organizations (SDOs) to ensure that the 

published methods that practitioners employ are scientifically valid, and the resulting claims are 

trustworthy.

The STRP panel will consist of an independent and diverse panel, including subject matter experts, 

human factors scientists, quality assurance personnel, and legal experts, which will be tasked with 

evaluating the proposed standard based on a comprehensive list of science-based criteria.

For more information about this important process, please visit our website 

at: https://www.nist.gov/topics/organization-scientific-area-committees-forensic-science/scientifictechnical-review-panels. 
OSAC 2022-S-0019 Standard Guide for 

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1 Standard Guide for Forensic Examination of Fibers

2

3 1. Scope 

4

5 1.1 This document is an introduction to the examination of textile fibers in forensic casework. It is intended to 

6 assist individuals who conduct forensic fiber analyses in their evaluation, selection, and application of tests that can 

7 be of value to their examinations. The goal is to provide a consistent approach to forensic fiber analysis. Detailed 

8 descriptions of procedures for many of the techniques are addressed in separate documents (E2224, E2225, E2227, 

9 E2228). This document is not intended as a detailed process description or rigid scheme for the analysis and 

10 comparison of fibers, but as a guide to the strengths and limitations of each analytical technique. 

11 1.2 This standard is intended for use by competent forensic science practitioners with the requisite formal 

12 education, discipline-specific training (see Practice E2917), and demonstrated proficiency to perform forensic 

13 casework. 

14 1.3 This guide does not purport to address all of the safety concerns, if any, associated with its use. It is the 

15 responsibility of the user of this standard to establish appropriate safety and health practices and determine the 

16 applicability of regulatory limitations prior to use.

17 1.4 This international standard was developed in accordance with internationally recognized principles on 

18 standardization established in the Decision on Principles for the Development of International Standards, Guides and 

19 Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

20

21 2. Referenced Documents 

22

2.1 ASTM Standards:1 23

24 D123 Terminology Relating to Textiles

25 D629 Standard Test Methods for Quantitative Analysis of Textiles

26 D4845 Terminology Relating to Wool

27 D4849 Standard Terminology Related to Yarns and Fibers

28 D7641 Guide for Textile Fibers

29 E620 Practice for Reporting Opinions of Scientific or Technical Experts

30 E1459 Guide for Physical Evidence Labeling and Related Documentation

31 E1492 Practice for Receiving, Documenting, Storing, and Retrieving Evidence in a Forensic Science 

32 Laboratory

33 E1732 Terminology Relating to Forensic Science

34 E2224 Guide for Forensic Analysis of Fibers by Infrared Spectroscopy

35 E2225 Guide for Forensic Examination of Fabrics and Cordage

36 E2227 Guide for Forensic Examination of Non-Reactive Dyes in Textile Fibers by Thin-Layer 

37 Chromatography

38 E2228 Guide for Microscopical Examination of Textile Fibers

39 E2917 Practice for Forensic Science Practitioner Training, Continuing Education, and Professional 

40 Development Programs

41 WK78748 Practice for a Forensic Fiber Training Program

42 WK 78749 Guide for Microspectrophotometry in Forensic Fiber Analysis

43

2.2 AATCC Standards:2 44

45 AATCC Test Method 20: Qualitative Test Method 20–2013 Fiber Analysis: Qualitative 

46

47 2.3 Other Documents:

1

For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual 

Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website.

2 Available from American Association of Textile Chemists and Colorists (AATCC), P.O. Box 12215, Research Triangle Park, NC 27709-2215, 

http://www.aatcc.org.
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ANAB ANSI 31253 48

ISO/IEC 17025 General Requirements for the Competence of Testing and Calibration Laboratories4 49

50 SWGMAT Introduction to Forensic Fiber Examination

51

52 3. Terminology 

53

54 3.1 Definitions— For additional terms commonly employed for forensic fiber examinations, see E1732 and E2228. 

55 For additional terms relating to textiles and wool, see D123, D4845, and D7641.

56 3.2 Definitions of Terms Specific to This Standard:

57 3.2.1 animal fiber, n—any natural protein-based fiber. See D7641

58 3.2.2 generic class, n—as used with textile fibers, a grouping having similar chemical compositions or specific 

59 chemical 

60 characteristics. D123

61 3.2.3 inorganic fibers, n—a class of fibers of natural mineral origin (for example, chrysotile asbestos) and 

62 manmade 

63 mineral origin (for example, fiberglass). E2228

64 3.2.4 manufactured fiber, n—a class name for various genera of fibers (including filaments) produced from fiber 

65 forming substances which can be (1) polymers synthesized from chemical compounds [synthetic fibers], (2) 

66 modified or transformed natural polymers [regenerated fibers], and (3) minerals, for example, glasses. E2228

67 3.2.4.1 Discussion—Acrylic, nylon, polyester, olefin, urethane, and polyvinyl are examples of fiber 

68 synthesized from chemical compounds. Cellulose based fibers, such as acetate and rayons, and alginate fibers are 

69 examples of modified or transformed polymers. D123

70 3.2.5 natural fibers, n—a class name for various genera of fibers (including filaments) of: (1) animal (that is, 

71 silk and wool); (2) mineral (that is, asbestos); or (3) vegetable origin (that is, cotton, flax, jute, and ramie). E2228

72 3.2.6 synthetic fibers, n—a class of manufactured polymeric fibers, which are synthesized from chemical 

73 compounds (for example, nylon and polyester). 

74 3.2.7 target fibers, n—questioned fibers that an examiner selects for further examination based on their 

75 resemblance to the known sample. 

76 3.2.8 textile, n—a general term for fibers, yarn intermediates, yarns, fabrics, and products that retain all the 

77 strength, flexibility, and other typical properties of the original fiber or filaments.

78 3.2.8.1 Discussion—General, a structure made from any combination of natural or manufactured fibers, 

79 having either a measured staple length or a continuous filament length, that can be in the form of a woven, 

80 nonwoven, braided, plaited, knitted, entangled or twisted product and which retains its characteristic flexibility and 

81 drape. Specific, as applied to: (1) staple fibers and filaments suitable for conversion to or use as yarns, or for the 

82 preparation of nonwoven fabrics, (2) yarns made from natural or manufactured fibers, (3) fabrics and other 

83 manufactured products made from fibers as defined above, and form yarns, and (4) garments and other articles 

84 fabricated wholly from one or more of the above, and articles made principally from the above when the products 

85 retain the characteristic flexibility and drape of the original fabrics. D123

86 3.2.9 textile fiber, n—a generic term for the various types of matter that can be transformed into a yarn having a 

87 length, at least 100 times its diameter, and which can be used to produce a flexible structure by weaving; knitting; 

88 braiding; felting or any other means of processing. 

89 3.2.9.1 Discussion—The matter transformed into a textile fiber can be either natural or manufactured. In 

90 addition to having a high ratio of length to thickness, the textile fiber also needs to have sufficient strength, 

91 cohesiveness, and flexibility.

92

93 4. Summary of Guide 

94

95 4.1 The basic activities involved in a fiber examination include case assessment, the search for and collection of 

96 fibers, preparation of the sample(s) for analysis, analysis using appropriate techniques, and evaluation of results.

97 4.2 The analysis of evidentiary fiber samples includes the examination of physical characteristics, optical 

3 Available from ANSI National Accreditation Board, 330 E. Kilbourn Ave, Suite 926, Milwaukee, WI, 53202, https://anab.ansi.org/2018-isoiec-17025-forensic-accreditation-documents-0.

4 Available from International Organization for Standardization (ISO), ISO Central Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 

Vernier, Geneva, Switzerland, http://www.iso.org.
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98 properties, color, and chemical composition. The techniques described in this document provide complementary 

99 information and should be selected and employed in an order that considers sample preservation and the amount of 

100 discriminating information that can be obtained.

101

102 5. Significance and Use 

103

104 5.1 Fibers are frequently encountered in casework, whether it be through the evidentiary item itself (e.g., clothing, 

105 rope), or

106 through the processing and collection of fibers from evidentiary items. Fibers can be exchanged between 

107 individuals, between individuals and objects, and between objects. 

108 5.2 Fibers are subjected to a variety of manufacturing processes in order to produce textile materials for 

109 application in a

110 wide range of industries (e.g., automotive, clothing, home furnishing). Factors such as end use, current trends, and 

111 availability influence the type and color of fibers incorporated into textiles.

112 5.3 Fibers exhibit a wide range of microscopic characteristics and optical properties due to the manufacturing 

113 process, end use, and exposure to various environmental conditions. These characteristics and properties are observed, 

114 analyzed, and compared during a fiber examination.

115

116 6. Case Assessment

117

118 6.1 In the case assessment phase, the examiner determines what samples are to be compared or identified. Sample 

119 size, sample variability, condition, environmental effects, relevant case circumstances, and collection and packaging 

120 techniques are all taken into account and the examiner chooses analytical techniques, sample preparation schemes, 

121 testing sequences, and degree of sample alteration and consumption that are suitable to the specific case.

122 6.2 As practicable, evaluate questioned fibers prior to known fiber samples during the examination process.

123 6.3 During case assessment, the examiner is cognizant of potential biasing effects resulting from task-irrelevant 

124 information (1).

125

126 7. Evidence Handling 

127

128 7.1 Follow the general requirements set forth in Practice E1492 and Guide E1459 if handling and tracking 

129 evidence.

130 7.2 Each laboratory develops appropriate procedures concerning sample size, collection, packaging, preservation, 

131 and order of examinations in order to prevent contamination and loss of fibers (2, 3).

132 7.2.1 Collect evidentiary items as soon as possible to mitigate the loss of fibers and other types of trace evidence.

133 7.2.2 Handling or transport can alter the location of a transferred fiber on a particular item of evidence (12).

134 7.3 Multiple kinds of evidence requiring the expertise of different forensic disciplines can be present on a single 

135 item. This can include various types of trace materials (e.g., hairs, fibers, paint, glass, explosives), as well as 

136 fingerprints and DNA. Prior to processing an item, consider the types of evidence potentially present and the impact 

137 that fiber examinations have on the ability of other examiners to perform future analyses. Examiners should confer 

138 before work is undertaken to ensure proper examination order and recovery of evidence. Unless circumstances 

139 dictate otherwise, the trace materials are collected and preserved prior to other examinations (2, 3). 

140 7.4 Samples are collected in a manner consistent with generally-recognized and accepted sampling techniques.

141

142 8. Types of Exams 

143

144 8.1 During a forensic fiber examination, two basic types of analysis are conducted. These analyses include fiber145 type identification and fiber comparison (13-15).

146 8.2 Fiber-type identifications are performed to provide investigative leads and possible end-use information. The 

147 Federal Trade Commission has defined classifications to include manufactured fiber definitions (Table 1), and fibers 

148 are analyzed to determine to which generic class (e.g., cotton, polyester) they belong (16). This analysis requires a 

149 sufficient number of analytical techniques to unequivocally place the questioned fiber into one and only one generic 

150 class. There are two broad categories of classification: natural fibers and manufactured fibers. Each can be further 

151 broken down into sub-classifications. 

152 8.2.1 Natural fibers are obtained from plants, animals, or geological materials.
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153 8.2.2 Manufactured fibers can be further described as regenerated, synthetic, or mineral based on the 

154 starting materials used to form the fibers.

155 8.3 Fiber comparisons are conducted to determine if (a) questioned fiber(s) exhibit(s) the same physical 

156 characteristics, optical properties, color, and chemical composition as fiber(s) comprising part or all of a known 

157 sample in order to assess whether the known sample can or cannot be included as a possible source. The same 

158 process can also be used to compare two or more questioned fibers in order to determine if they could share a 

159 common source. 

160 8.4 The fiber types found at a crime scene or on a person of interest affects their evidential value. 

161 8.4.1 Certain types of fibers, such as colorless cotton and indigo-dyed blue cotton (denim), are so common as to 

162 be of limited evidential value, except in rare cases (e.g., colorless cotton fibers embedded or fused on to a deployed 

163 airbag or a scrap of blue denim fabric caught on the undercarriage of a vehicle suspected to be involved in a hit-and164 run).

165 8.4.2 Natural Fiber Use in Textile Production

166 8.4.2.1 Cotton fibers are the most commonly-used plant fibers in textile production. The type of cotton, cross167 sectional shape, length, and the degree of twist contribute to the diversity found in cotton fibers. Processing 

168 techniques, such as mercerization, and color applications also influence the comparative value of cotton fibers. The 

169 presence of other less-common plant fibers recovered at a crime scene or on the clothing of a person of interest can 

170 increase the significance of the fiber evidence.

171 8.4.2.2 The most common animal fiber used in textile production is wool originating from sheep. The 

172 fineness or coarseness of woolen fibers often dictates the end use of wool. In general, the finer woolen fibers are 

173 used in the production of clothing, whereas the coarser fibers are found in carpet. The diameter and the degree of 

174 scale protrusion of the fibers are other important characteristics. Woolen fibers from other animals, including camel, 

175 alpaca, goat (cashmere and mohair), and rabbit (angora) are also found in textiles. The identification of less-common 

176 animal fibers at a crime scene or on the clothing of a person of interest can have increased significance as compared 

177 to that of sheep’s wool.

178 8.4.3 Manufactured Fiber Use in Textile Production

179 8.4.3.1 Over half of all fibers used in the production of textile materials are manufactured (17, 18). Certain 

180 types of manufactured fibers are encountered in casework more often than others. The amount of production, the end 

181 use, the cross-sectional shape, microscopic characteristics, and other traits of the fiber affect the significance of a 

182 particular fiber type.

183

184 9. Procedure

185

186 9.1 Select known sample(s) representative of the observed variation (e.g., color, texture, luster) within the textile. 

187 Differences could arise in measurements of fiber samples from the same garment or textile because of differences in 

188 weathering (e.g., sunlight exposure), spot staining/bleaching, or repaired areas (e.g., use of a fabric marker to cover a 

189 discolored area, application of a patch). 

190 9.2 Techniques for the identification and comparison of fibers (19-24) are found in Table 2 (shaded boxes represent 

191 techniques which are highly recommended) and are presented in no particular order. Some techniques allow greater 

192 discrimination between apparently similar samples than others (25-33). The particular technique(s) employed by each 

193 examiner or laboratory will depend upon available equipment and the nature and extent of the fiber evidence in each 

194 specific case. 

195 9.3 For any given fiber identification and comparison, not all the techniques listed in Table 2 are necessary. Fiber 

196 type, sample size, and condition should be considered if determining which techniques to use. Those requiring more 

197 sample preparation or consumption should be performed after less-destructive techniques. If sample size is limited, 

198 nondestructive techniques are exhausted before subjecting the sample to tests which could permanently alter or 

199 destroy the sample [e.g., Fourier-transform infrared (FTIR) spectroscopy, pyrolysis]. If an exclusionary difference is 

200 found at any point during the fiber comparison process, then no further analysis is necessary. 

201 9.4 The analytical tests performed are left to the discretion of the examiner; however, at a minimum, a fiber examiner 

202 employs a stereomicroscope, light microscope, and a polarized light microscope for identification. In addition, the 

203 fiber examiner uses a comparison microscope and at least one other color comparison technique if performing fiber 

204 comparisons. 

205 9.4.1 Using the comparison microscope, an examiner views fibers side-by-side at the same magnifications in 

206 visible light, and by alternative lighting, such as polarized light or fluorescence, if the equipment allows. For color 

207 comparison, an examiner employs at least one analytical test [e.g., microspectrophotometry (MSP), thin layer 
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208 chromatography (TLC)] along with comparison microscopy. Fourier-transform infrared spectroscopy (or another 

209 technique which provides comparable chemical information) is strongly recommended for the characterization of 

210 manufactured fibers. 

211 9.4.2 A typical fiber examination workflow is shown in Figure 1. This figure represents one of several possible 

212 workflows used to identify and compare fibers and does not preclude the use of other workflows to perform fiber 

213 examinations. General descriptions of techniques employed during a fiber examination are listed in sections 9.5 

214 through 9.8 in order to provide additional guidance for the selection of appropriate techniques. 

215 9.5 Microscopical Examinations 

216 9.5.1 Microscopical examinations provide information about the physical and optical properties of a fiber, 

217 allowing for the determination of general fiber type and the differentiation of fiber samples. 

218 9.5.1.1 Low-magnification stereomicroscopy is used for the search, recognition, manipulation, and collection 

219 of apparent textile fibers. This technique also offers a limited characterization of the fiber’s physical characteristics.

220 9.5.1.2 High-magnification light microscopy is employed to characterize the fiber’s physical and microscopic 

221 characteristics (e.g., color, diameter, cross-sectional shape, pigment, voids, inclusions).

222 9.5.1.3 Comparison microscopy allows the examiner to view two fiber samples side-by-side while employing 

223 the same magnification and lighting conditions. Comparison using polarized light or fluorescence is performed if the 

224 equipment allows.

225 9.5.1.4 Polarized light microscopy (PLM), an essential part of the fiber examination process, is used to observe 

226 and measure the optical properties of a fiber. These properties are imparted during the manufacturing process and are 

227 used to determine the general fiber type (e.g., acrylic, nylon, polyester).

228 9.5.1.5 Fluorescence microscopy is a technique used to observe the optical properties of the fiber itself as well 

229 as those imparted to the fiber by various dyes, optical brighteners, chemical treatment/damage or contaminants.

230 9.5.2 Strengths of microscopical examination techniques include: 

231 ● Highly discriminating and reliable; 

232 ● Generally non-destructive; 

233 ● Rapid; and

234 ● Requires minimal sample preparation. 

235 9.5.3 Limitations of microscopical examination techniques include:

236 ● Physical and optical properties of fibers can be impacted by sample handling, physical 

237 damage or environmental factors. 

238 ● Very dark fibers can impede the ability of these techniques to resolve physical and optical 

239 properties of fiber samples. 

240 ● Potential for quenching of fiber samples when performing fluorescence microscopy.

241 9.5.4 For more detailed information regarding microscopical examination of fibers, refer to ASTM E2228 Guide 

242 for Microscopical Examination of Textile Fibers.

243 9.6 Color Examinations

244 9.6.1 Color is highly variable among textiles. Dyes and pigments belong to numerous chemical categories with 

245 more than a dozen different application techniques (34, 35). Color is a highly discriminating characteristic due to the 

246 variety of dye productions, batch variations, and the multitude of colors available. Individual fibers can be colored 

247 before being spun into yarn, yarns can be dyed after being spun, or the fabric can be dyed after its construction as a 

248 fabric or garment (35-37). Color can also be applied to the surface of a fabric by printing. The absorption of the dye 

249 along the fiber length can vary based on the dyes, dyeing processes used, and the fiber type. 

250 9.6.2 For color comparison, an examiner employs comparison microscopy along with another analytical 

251 technique, such as microspectrophotometry or TLC. If another analytical technique is not performed, the reason is 

252 documented.

253 9.6.3 Microspectrophotometry is an instrumental technique that provides color measurement data for fibers using 

254 transmitted light. During fiber examinations, the absorption of visible light is measured and compared. If samples are 

255 compared and no differences are detected in the visible region, they can be further analyzed in the UV region using 

256 MSP. For more detailed information regarding MSP, refer to ASTM WK78749 Guide for Microspectrophotometry in 

257 Forensic Fiber Analysis. 

258 9.6.3.1 Strengths of this technique:

259 ● Provides objective color measurement data.
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260 ● Generally considered to be non-destructive (note potential for photobleaching below). 

261 9.6.3.2 Limitations of this technique include:

262 ● Absorption can be impacted by sample handling, physical damage or environmental factors. 

263 ● Very dark or very light fibers may display data of limited value in the visible region.

264 ● Certain fiber types naturally absorb in the UV region (e.g., wool, polyester), limiting data collection and 

265 interpretation.

266 ● Inability to differentiate between individual dye components. 

267 ● Potential for photobleaching of fiber samples.

268 9.6.4 Thin layer chromatography is a dye analysis technique requiring the extraction of dye from the colored fiber. 

269 Different dye mixtures can produce similarly-colored fibers that are difficult to distinguish by optical techniques such 

270 as MSP. By first extracting the dye and then separating the individual dye components, TLC provides complementary 

271 information to further discriminate between fiber colorants. For more detailed information regarding TLC, refer to 

272 ASTM E2227 Guide for Forensic Examination of Non-Reactive Dyes in Textile Fibers by Thin-Layer 

273 Chromatography.

274 9.6.4.1 Strengths of this technique include:

275 ● Simple dye analysis technique; and

276 ● Provides complementary information to MSP.

277 9.6.4.2 Limitations of this technique include: 

278 ● Destructive; and

279 ● Limited by the small amount of dye present in a single fiber. 

280 9.7 Fourier-Transform Infrared Spectroscopy 

281 9.7.1 Fourier-transform infrared spectroscopy is an instrumental technique that employs the use of infrared 

282 radiation to obtain information about the chemical structure of fibers in order to determine the fiber-type (e.g., nylon, 

283 polyester), sub-type (e.g., identification of acrylic fiber co-polymers), and inorganic fillers (if present). FTIR 

284 spectroscopy is typically employed following microscopical and color examination due to potential alteration of fiber 

285 morphology. For more detailed information regarding FTIR spectroscopy, refer to ASTM E2224 Guide for the 

286 Forensic Analysis of Fibers by Infrared Spectroscopy.

287 9.7.2 Strengths of this technique: 

288 ● Provides chemical structure and fiber-type information; and

289 ● Requires minimal sample preparation.

290 9.7.3 Limitations of this technique include:

291 ● Sample preparation can alter the physical shape and characteristics of the fiber; and 

292 ● The presence of surface contaminants can interfere with spectral interpretation. 

293 9.8 Additional techniques

294 9.8.1 Capillary Electrophoresis (CE) is a chromatographic technique used to analyze very small amounts of dye 

295 from colored fibers. 

296 9.8.1.1 Strengths of this technique include:

297 ● Provides complementary information to MSP; and 

298 ● More efficient than TLC.

299 9.8.1.2 Limitation of this technique:

300 ● Destructive. 

301 9.8.2 Pyrolysis (Py) is an instrumental technique in which fibers are thermally decomposed, followed by analysis 

302 using either gas chromatography (Py-GC), mass spectrometry (Py-MS) or a combination of both (Py-GC-MS) to 

303 identify the fiber-type and sub-type. 

304 9.8.2.1 Strength of this technique:

305 ● Provides fiber-type and sub-type information.

306 9.8.2.2 Limitation of this technique: 

307 ● Destructive.

308 9.8.3 Raman spectroscopy is an instrumental technique that uses a monochromatic source (i.e., a laser emitting a 

309 wavelength in the ultraviolet, visible or near-infrared spectral range) to produce an inelastic light scattering effect 

310 which provides information primarily about fiber dyes, pigment components, the polymer, delustrants, and fillers. 

311 9.8.3.1 Strengths of this technique include:
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312 ● Provides complementary information to FTIR; and 

313 ● Requires minimal sample preparation.

314 9.8.3.2 Limitation of this technique:

315 ● Analysis can be hindered by background fluorescence or thermal degradation of the 

316 sample.

317 9.8.4 High performance liquid chromatography (HPLC) is a chromatographic technique used to analyze dyes 

318 extracted from short lengths of colored fibers. High performance liquid chromatography employs a micro-extraction 

319 process that is effective for a wide range of fiber types, dye types, and dye mixtures. 

320 9.8.4.1 Strengths of this technique include:

321 ● Provides quantitative data; 

322 ● Offers better resolution of dyes than TLC; 

323 ● Effective for a wide range of fiber types, dye types and dye mixtures; and

324 ● Provides complementary information to further discriminate between fiber colorants. 

325 9.8.4.2 Limitations of this technique include:

326 ● Destructive; and 

327 ● Separation of various dye types on a single chromatographic system can be difficult. 

328 9.8.5 Elemental analysis techniques such as scanning electron microscopy/energy dispersive X-ray spectroscopy 

329 (SEM/EDX) and X-ray fluorescence (XRF) can provide information about the elemental composition of fibers.

330 9.8.5.1 Strengths of these techniques include: 

331 ● Provide information about inorganic components imparted to a fiber through the 

332 manufacturing process, additives/finishing agents, and environmental contaminants. 

333 ● SEM-EDX and XRF are complementary techniques; however, XRF is more sensitive to 

334 higher atomic weight elements.

335 9.8.5.2 Limitations of these techniques include that:

336 ● X-ray production for SEM-EDX is dependent on beam energy, composition and density of 

337 the sample, and energy of the X-rays; and

338 ● XRF is less sensitive to lower atomic weight elements.

339 9.8.6 Techniques such as cross-sectioning, melting point and solubility can be used to obtain information about the 

340 physical characteristics and chemical properties of a manufactured fiber. It is important to consider the sequence of 

341 analysis when incorporating these destructive techniques into a fiber examination.

342 9.8.6.1 Strength of these techniques: 

343 ● Provide information about a manufactured fiber's physical and chemical properties.

344 9.8.6.2 Limitation of these techniques: 

345 ● Can physically alter or destroy the fiber sample. 

346 9.8.7 Additional techniques specific to natural fibers include the drying twist test, ashing, and staining. Cross347 sectioning can also be used to obtain additional information about a natural fiber’s cross-sectional shape and type. As 

348 with previously-mentioned techniques, consideration is given to the amount of sample available, and the destructive 

349 nature of the techniques employed. 

350

351 10. Results

352

353 10.1 In a fiber case, the forensic examiner analyzes the evidence, interprets the data and observations, and reports 

354 an opinion of the findings.

355 10.2 The comparative analysis of two or more fibers involves the evaluation of physical characteristics, optical 

356 properties, color, and chemical composition.

357 10.2.1 If one or more exclusionary differences are recognized between compared fibers based on the measured or 

358 observed characteristics, the sources of these fibers are distinguishable. In fiber comparisons, this is described as an 

359 exclusion or elimination: two or more fibers are excluded as having originated from the same source based on the 

360 sample provided (38).

361 101.2.2 If no exclusionary differences are recognized between compared fibers based on the measured or observed 

362 characteristics, the sources of these fibers cannot be distinguished by these techniques. In fiber comparisons, this is 

363 described as a source association based on class characteristics, indicating the possibility that the fibers originated 

364 from the same source. Since different fiber sources can share class characteristics, this opinion does not indicate that 
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365 the fibers came from a specific source. 

366

367 11. Evaluation of the Results

368

369 11.1 When a specific item, such as fabric from a person of interest or a scene, is included as a possible source of a 

370 questioned fiber, or if two or more questioned fibers could share a common source, the evidential value is dependent 

371 upon many factors. 

372 11.1.1 Source factors 

373 11.1.1.1 Fiber type; 

374 11.1.1.2 Intra-source variability (e.g. trunk liner, patchwork garment); 

375 11.1.1.3 Fiber characteristics; 

376 11.1.1.4 Condition of a specific source (e.g., shirt recovered from a hit-and-run victim exhibiting damage); and

377 11.1.1.5 Presence of contaminants, damage, or other acquired characteristics (e.g., the questioned fiber exhibits 

378 characteristics of heat exposure and the victim clothing is burned or singed). 

379 11.1.2 Activity or case-related factors (e.g., transfer [4-7], persistence [8-11], efficiency of recovery) (13, 14)

380 11.1.2.1 Location, quantity, and acquired characteristics of the recovered fibers (e.g., fibers embedded in a 

381 deployed airbag, fibers embedded in blood on a weapon); 

382 11.1.2.2 Number and types of fibers associated to single or multiple sources (e.g., multiple black polyester fibers 

383 associated to a shirt, multiple blue cotton fibers and multiple blue polyester fibers associated to a single shirt, apparent 

384 cross transfer of fibers between two shirts);

385 Note 1: A greater number of associated questioned fibers provides increased support for recent and direct contact 

386 occurring with the known fiber source. The converse is not necessarily true, however, and even one fiber association 

387 can have evidential value. Finding no fiber associations does not necessarily mean that no contact occurred. 

388 11.1.2.3 Nature of contact;

389 Note 2: The type of physical contact between two sources can influence the number of fibers transferred and the 

390 value placed on their discovery. Brief contact is less likely to transfer multiple fibers than extended and more forceful 

391 contact. 

392 11.1.2.4 Composition, construction and condition of a textile; 

393 Note 3: Tightly-woven or tightly-knit fabrics shed fewer fibers than loosely-knit or loosely-woven fabrics. 

394 Likewise, fabrics composed of filament fibers shed less than fabrics composed of staple fibers. Newer fabrics can 

395 have an abundance of loosely-adhering fibers on the surface of the fabric, while worn fabrics can have damaged areas 

396 that easily shed fibers. Damage to a fabric caused during physical contact can greatly increase the potential of fiber 

397 transfer.

398 11.1.2.5 And environmental factors (e.g., fading, discoloration, singeing).

399 11.2 The ability to discriminate between similar types and colors of recovered fibers is important when assessing 

400 the significance of an association (25, 26, 29, 30). 

401 11.3 If information about the relevant fiber population is available (e.g., published discrimination studies, product 

402 manufacturing and distribution information), the significance of the features recorded during the examination can be 

403 evaluated.

404 11.4 The analytical scheme an examiner employs directly impacts the ability to discriminate between fibers and, 

405 ultimately, 

406 the significance of findings. If an analytical scheme is not inclusive of the assessment of the physical characteristics 

407 and 

408 optical properties, analysis of color, and analysis of chemical composition when applicable, then a qualifying 

409 statement is 

410 warranted.

411 11.5 Background information regarding the potential sources involved, possible prior contact, and the environment 

412 where 

413 questioned fibers were recovered affects the significance of the association. Be cognizant of potential biasing effects 

414 resulting from task-irrelevant information (39, 40).

415

416 12. Documentation
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417

418 12.1 Contemporaneously record all observations made during the examination. Ensure the examination notes 

419 accurately reflect all observations, the evidence analyzed, the techniques employed, and all results. Notes should be 

420 sufficient to allow an independent analyst to understand and evaluate all the work performed, analyze and interpret 

421 the data, and reach independent opinions. 

422 12.2 Case notes include acquired instrumental data that was used to reach a finding. 

423 12.3 Reports are written in accordance with ASTM standards (E620) and include the results of the analysis, an 

424 interpretation of the results, and qualifying statements that further describe the strengths and limitations of the 

425 evidence.

426 12.4 Examiners follow all accreditation guidelines as appropriate (e.g., ISO/IEC 17025 [2, 41]) as well as their 

427 laboratory’s standard operating procedures and quality assurance guidelines.

428

429 13. Keywords

430 Forensic science, fiber, fiber comparison, instrumental analysis.

431

432 Table 1 Federal Trade Commission Rules and Regulations Under the Textile Products Identification Act, 16 

433 CFT Part 303 Pursuant to the provisions of Section 7 of the Act, the following generic names for manufactured 

434 fibers, together with their respective definitions, are hereby established (16): 

435

Fiber Name Definition

Acetate A manufactured fiber in which the fiber-forming substance is cellulose acetate. Where not less 

than 92% of the hydroxyl groups are acetylated the term triacetate may be used as a generic 

description of the fiber. 

Acrylic A manufactured fiber in which the fiber-forming substance is any long-chain synthetic polymer 

composed of at least 85% by weight of acrylonitrile units. 

Anidex A manufactured fiber in which the fiber-forming substance is any long-chain synthetic polymer 

composed of at least 50% by weight of one or more esters of a monohydric alcohol and acrylic 

acid. 

Aramid A manufactured fiber in which the fiber-forming substance is any long-chain synthetic 

polyamide in which at least 85% of the amide linkages are attached directly to two aromatic 

rings. 

Azlon A Manufactured fiber in which the fiber-forming substance is composed of any regenerated 

naturally occurring proteins. 

Elastoester A manufactured fiber in which the fiber-forming substance is a long chain synthetic polymer 

composed of at least 50% by weight of aliphatic polyether and at least 35% by weight of 

polyester, as defined in 303.7(c). 

Fluoropolymer A manufactured fiber containing at least 95% of a long chain polymer synthesized from aliphatic 

fluorocarbon monomers. 

Glass A manufactured fiber in which the fiber-forming substance is glass. 

Lyocel A manufactured fiber composed of precipitated cellulose and produced by a solvent extrusion 

process where no chemical intermediates are formed. 

Melamine A manufactured fiber in which the fiber-forming substance is a synthetic polymer composed of at 

least 50% by weight of a crosslinked melamine polymer. 

Metallic A manufactured fiber composed of metal, plastic-coated metal, metal-coated plastic, or a core

completely covered by metal. 

Modacrylic A manufactured fiber in which the fiber-forming substance is any long-chain synthetic polymer 

composed of less than 85% but at least 35% by weight of acrylonitrile units. 
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Nylon A manufactured fiber in which the fiber-forming substance is any long-chain synthetic 

polyamide in which less than 85% of the amide linkages are attached directly to two aromatic 

rings. 

Nytril A manufactured fiber containing at least 85% of a long chain polymer of vinylidene dinitrile 

where the vinylidene dinitrile content is no less than every other unit in the polymer chain. 

Novoloid A manufactured fiber containing at least 85% by weight of a crosslinked novolac. 

Olefin A manufactured fiber in which the fiber-forming substance is any long-chain synthetic polymer 

composed of at least 85% by weight of ethylene, propylene, or other olefin units. 

PBI A manufactured fiber in which the fiber-forming substance is a long chain aromatic polymer 

having reoccurring imidazole groups as an integral part of the polymer chain. 

PLA A manufactured fiber in which the fiber-forming substance is composed of at least 85% by 

weight of lactic acid ester units derived from naturally occurring sugars. 

Polyester A manufactured fiber in which the fiber-forming substance is any long-chain synthetic polymer 

composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, 

including but not restricted to substituted terephthalate units and parasubstituted 

hydroxybenzoate units. Where the fiber formed by the interaction of two or more chemically 

distinct polymers (of which none exceeds 85% by weight), and contains ester groups as the 

dominant functional unit (at least 85% by weight of the total polymer content of the fiber), 

and which, if stretched at least 100%, durably and rapidly reverts substantially to its unstretched 

length when the tension is removed, the term elasterell-p may be used as a generic 

description of the fiber. 

Rayon A manufactured fiber composed of regenerated cellulose, as well as manufactured fibers 

composed of regenerated cellulose in which substituents have replaced not more than 15% of the 

hydrogens of the hydroxyl groups. Where the fiber is composed of cellulose precipitated from an 

organic solution in which no substitution of the hydroxyl groups takes place and no chemical 

intermediates are formed, the term lyocell may be used as a generic description of the fiber. 

Rubber A manufactured fiber in which the fiber-forming substance is comprised of a natural or synthetic 

rubber, including the following categories: 

(1) A manufactured fiber in which the fiber-forming substance is a hydrocarbon such as natural 

rubber, polyisoprene, polybutadiene, copolymers of dienes and hydrocarbons, or amorphous 

(noncrystalline) polyolefins. 

(2) A manufactured fiber in which the fiber-forming substance is a copolymer of acrylonitrile 

and a diene (such as butadiene) composed of not more than 50% but at least 10% by weight of 

acrylonitrile units. The term lastrile may be used as a generic description for fibers falling within 

this category. 

(3) A manufactured fiber in which the fiber-forming substance is a polychloroprene or a 

copolymer of chloroprene in which at least 35% by weight of the fiber-forming substance is 

composed of chloroprene units. 

Saran A manufactured fiber in which the fiber-forming substance is any long-chain synthetic polymer 

composed of at least 80% by weight of vinylidene chloride units. 

Spandex A manufactured fiber in which the fiber-forming substance is any long-chain synthetic polymer 

composed of at least 85% of a segmented polyurethane. 
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Sulfar A manufactured fiber in which the fiber-forming substance is a long chain synthetic polysulfide 

in which at least 85% of the sulfide linkages are attached directly to two aromatic rings. 

Vinal A manufactured fiber in which the fiber-forming substance is any long-chain synthetic polymer 

composed of at least 50% by weight of vinyl alcohol units and in which the total of the vinyl 

alcohol units and any one or more of the various acetal units is at least 85% by 

weight of the fiber. 

Vinyon A manufactured fiber in which the fiber-forming substance is any long-chain synthetic polymer 

composed of at least 85% by weight of vinyl chloride units. 

436 Table 2 Techniques for the identification and comparison of fibers. Shaded boxes represent techniques which 

437 are highly recommended.

Physical Characterization Optical Properties Microchemical 

Analysis

Color/Dye/Pigment 

Analysis

Instrumental 

Analysis

Stereomicroscopy PLM Solubility Comparison Microscopy FTIR 

(Manufactured 

Fibers)

Light Microscopy/ 

Comparison Microscopy

Light Microscopy/ 

Comparison Microscopy

Staining 

(Natural Fibers)

MSP, TLC or a 

combination of both 

SEM-EDS/XRF 

SEM Fluorescence Microscopy CE PyGC/PyGCMS 

Melting Point Raman Raman 

Physical Test (Dry Twist, 

Ashing, etc.) HPLC

438

439
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440

441

442 14. References

443

444 (1) Dror, I. E., “Cognitive and Human Factors in Expert Decision Making: Six Fallacies and the Eight Sources 

445 of Bias," Analytical Chemistry, Vol. 92, No. 12, June 8, 2020, pp. 7998–8004.

446 (2) Scientific Working Group for Materials Analysis, “Trace Evidence Quality Assurance Guidelines,” FBI 

447 Publication, Washington, D.C., 1999. Retrieved from: https://archives.fbi.gov/archives/about448 us/lab/forensic-science-communications/fsc/jan2000/swgmat.htm#laboratory%20audits

449 (3) Scientific Working Group for Materials Analysis, “Trace Evidence Recovery Guidelines,” FBI Publication, 

450 Washington, D.C., 1999. Retrieved from: 

451 https://www.asteetrace.org/static/images/pdf/04%20Trace%20Evidence%20Recovery%20Guidelines%20

452 %28Published%20in%20Forensic%20Science%20Communications%2C%20October%201999%29.pdf

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454 Forensic Science Society, Vol. 3, 1982, pp. 301-308.

455 (5) Lowrie, C. N., and Jackson, G., "Secondary Transfer of Fibers," Forensic Science International, Vol. 64, 

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457 (6) Pounds, C. A., and Smalldon, K. W., “The transfer of fibres between clothing materials during simulated 

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460 (7) Robertson, J., and Roux, C., “Transfer, Persistence and Recovery of Fibers.” In Robertson, J., Roux, C., and 
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Wiggins K. G. (Eds.), Forensic Examination of Fibres, 3rd 461 edition, Boca Raton: CRC Press, 2018, pp. 109-

462 119.

463 (8) Pounds, C. A., and Smalldon, K. W., “The Transfer of Fibres between Clothing Materials During 

464 Simulated Contacts and their Persistence During Wear: Part II—Fibre Persistence,” Journal of the Forensic 

465 Science Society, Vol. 15, No. 1, 1975, pp. 29-37.

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469 (10)Robertson, J., Kidd, C. B. M., and Parkinson, H. M. P., “The persistence of textile fibres transferred during 

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471 (11)Roux, C., Robertson, J., and Palmer, R., “Persistence and Recovery.” In Saukko, P. J., and Houck, M. M. 

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473 (12)Chewning, D., Deaver, K., and Christensen, A., “Persistence of Fibres on Ski Masks During Transit and 

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481 (16)Federal Trade Commission Rules and Regulations Under the Textile Products Identification Act, Title 15, 

482 U.S. Code Section 70, et seq. 16 CFR 303.7.

483 (17)Textile Exchange, Preferred Fiber & Materials Market Report 2019, accessed at 

484 https://textileexchange.org/wp-content/uploads/2019/11/Textile-Exchange_Preferred-Fiber-Material485 Market-Report_2019.pdf

486 (18)Textile Exchange, Preferred Fiber & Materials Market Report 2020, accessed at 

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490 (20)Catling, D. L., and Grayson, J., Identification of Vegetable Fibers, London: Chapman and Hall, 1982.

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492 Bioanalytical Chemistry, Vol. 394, No. 8, August 2009, pp. 2009-2018.

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495 (23)Hall, D., Practical Fiber Identification, Auburn: Auburn University, 1982.

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497 Roux, C., and Wiggins, K. G., Forensic Examination of Fibres 3rd Edition, Boca Raton: CRC Press, 2018, 

498 pp. 119-126. 

499 (25)Biermann, T. W., “Blocks of colour IV: the evidential value of blue and red cotton fibres,” Science and 

500 Justice, Vol. 47, No. 2, 2007, pp. 68-87.

501 (26)Cassista, A., and Peters, A. D., “Survey of red, green, and blue cotton fibers,” Canadian Society of 

502 Forensic Science Journal, Vol. 30, No. 4, 1997, pp. 225-231.

503 (27)Cook, R., and Wilson, C., “The significance of finding extraneous fibres in contact cases,” Forensic 

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505 (28)Houck, M. M., “Inter-comparison of unrelated fiber evidence,” Forensic Science International, Vol. 135, 

506 No. 2, 2003, pp. 146-149.

507 (29)Grieve, M. C., Biermann, T. W., and Schaub, K., “The individuality of fibres used to provide forensic 

508 evidence -- not all blue polyesters are the same,” Science and Justice, Vol. 45, No. 1, 2005, pp. 13-28.

509 (30)Palmer, R., Hutchinson, W., and Fryer, V., “The discimination of (non-denim) blue cotton,” Science and 

510 Justice, Vol. 49, 2009, pp. 12-18.

511 (31)Was-Gubala, J., “The kinetics of colour change in textile and fibres treated with detergent solutions Part I -

512 Colour perception and fluorescence microscopy analysis,” Science and Justice, Vol. 49, 2009, pp. 165-169.

513 (32)Was-Gubala, J., and Grzesiak, E., “The kinetics of colour change in textile and fibres treated with detergent 

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515 (33)Wiggins, K. G., Cook R., and Turner, Y. J., “Dye batch variation in textile fibers,” Journal of Forensic 
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516 Sciences, Vol. 33, 1998, pp. 998-1007.

517 (34)Aspland, J. R., “What are dyes? What is dyeing?” In AATCC Dyeing Primer, Research Triangle Park: 

518 American Association of Textile Chemists and Colorists, 1981.

519 (35)Clark, M., Handbook of Textile and Industrial Dyeing: Principles, Processes and Types of Dyes, 

520 Cambridge: Woodhead Publishing, pp. 20.

521 (36)Technical Manual of the American Association of Textile Chemists and Colorists, Research Triangle Park: 

522 AATCC, 2021.

523 (37)American Home Economics Association, Textiles and Clothing Section, Textile Handbook, Washington, 

524 DC: The American Home Economics Association, 1985.

525 (38)Uniform Language for Testimony and Reports for the Forensic Textile Fiber Discipline,” effective date 

526 3/1/21. Accessed at https://www.justice.gov/olp/uniform-language-testimony-and-reports on 1/28/2022.

527 (39)Kassin, S. M., Dror, I. E., and Kukucka, J., “The Forensic Confirmation Bias: Problem, Perspectives, and 

528 Proposed Solutions,” Journal of the Applied Research in Memory and Cognition, Vol. 2, No. 1, 2013, pp. 

529 42-52.

530 (40)National Commission on Forensic Science, “Ensuring That Forensic Analysis Is Based Upon Task531 Relevant Information,” National Institute of Standards and Technology (NIST), December 8, 2015.

532 (41)Grieve, M., Roux, C., Wiggins, K.G., Champod, C., and Taroni, F., “Quality Assurance, Report Writing 

533 and Examples of Casework Findings.” In Robertson, J., Roux, C., and Wiggins, K. (Eds.), Forensic 

534 Examination of Fibres 3rd Edition, Boca Raton: CRC Press, 2018, pp. 361-370.