Significance and Use
5.1 Qualitative and quantitative fiber identification is actively pursued by committee RA24 (Fiber Identification) of AATCC and presented in AATCC Test Methods 20 and 20A. Since precision and bias development is also part of the AATCC test methods, both AATCC and ASTM D13 have agreed that new development will take place in RA24. However, because there is valuable information still present in the ASTM standards, D13.51 has agreed Test MethodsD276 and D629 will be maintained as active standards by ASTM.
5.2 Test Methods D629 for the determination of quantitative analysis of textiles may be used for acceptance testing of commercial shipments but caution is advised since information on between-laboratory precision is lacking. Comparative tests as directed in 5.2.1 or in Standard Tables D1909 may be advisable.
5.2.1 In case of a dispute arising from differences in reported test results using Test Methods D629 for acceptance testing of commercial shipments, the purchaser and the supplier should conduct comparative tests to determine if there is a statistical bias between their laboratories. Competent statistical assistance is recommended for the investigation of bias. As a minimum, the two parties should take a group of test specimens which are as homogeneous as possible and which are from a lot of material of the type in question. The test specimen should then be randomly assigned in equal numbers to each laboratory for testing. The average results from the two laboratories should be compared using Student's t-test and an acceptable probability level chosen by the two parties before the testing began. If a bias is found, either its cause must be found and corrected or the purchaser and supplier must agree to interpret future test results in the light of the known bias.
5.3 The effects of the various reagents used in the chemical methods on the residual fibers in a blend depend upon the history of the fibers and, unless otherwise stated, are generally too small or too uncertain to warrant the application of correction factors.
5.4 Fiber composition is generally expressed either on the oven-dry mass of the original sample or the oven-dry mass of the clean fiber after the removal of nonfibrous materials. If nonfibrous materials are not first removed from the textile before the fiber analysis is carried out, or if the treatments described in Section 8 are incapable of removing them, any such materials present will increase the percentage of the fiber constituent with which they are removed during the analysis, assuming they are soluble in the solvent used.
5.5 The analytical methods are intended primarily for the separation of binary mixtures of fibers. These procedures may also be used for the analysis of mixtures containing more than two types of fibers by selecting the best combination of methods to use (Table 1). Since a sequence of solvents on a given fiber may produce different results than the expected results from a single solvent, it is advisable to determine the results of such sequential effects when testing multiple fiber blends. It is sometimes more convenient to separate mechanically the yarns in a textile which are of similar types, and then use the appropriate chemical method to analyze each of the components. Table 2 shows the solubilities of the various fibers in different chemical reagents.
Method No. 1—80 % acetone(cold)
Method No. 2— N-Butyrolactone
Method No. 3—90 % formic acid
Method No. 4—59.5 % sulfuric acid
Method No. 5—70 % sulfuric acid
Method No. 6—Sodium hypochlorite solution
Method No. 7—Curpammonia solution
Method No. 8—Hot xylene
Method No. 9—90 % formic acid
Method No. 10—N,N-dimethylacetamide
S  =  Soluble
PS  =  Partially Soluble
SS  =  Slightly Soluble (a correction factor may be applied)
I  =  Insoluble
Scope
1.1 These test methods cover procedures for the determination of the fiber blend composition of mixtures of the fibers listed in 1.2. Procedures for quantitative estimation of the amount of moisture and certain nonfibrous materials in textiles are also described, for use in the analysis of mixtures, but these are not the primary methods for the determination of moisture content for commercial weights.
1.2 These test methods cover procedures for the following fiber types:
1.2.1 Natural Fibers:
1.2.1.1 Cellulose-Base Fibers:
 Cotton
 Hemp
 Flax
 Ramie
1.2.1.2 Protein-Base Fibers:
 Animal hairs (other than wool)
 Silk, cultivated
 Silk, Tussah
 Wool
1.2.2 Man-Made Fibers:
1.2.2.1 Cellulose-Base Fibers:
 Acetate (secondary)
 Rayon, viscose or cuprammonium
 Triacetate
1.2.2.2 Synthetic-Base Fibers:
 Acrylic
 Aramid
 Modacrylic
 Nylon 6, Nylon 6-6, others
 Olefin
 Polyester
 Spandex
1.3 These test methods include the following sections and tables:
|
| Section |
|
| |
| Referenced Documents |  2 |
| Terminology |  3 |
| Summary of Methods |  4 |
| Uses and Significance |  5 |
| Sampling |  7 |
| Purity of Reagents |  6 |
| Moisture Content or Moisture Regain |  9 |
| Nonfibrous Materials |  8 |
| Mechanical Separation or Dissection | 10 |
| Chemical Test Methods: |
|
|  Summary of Methods | 11 |
|  Specimens and Symbols | 12 |
|  No. 1 Acetate Mixed With Other Fibers | 13 |
|  No. 2 Modacrylic Mixed With Cellulosic Fiber or Wool | 14 |
|  No. 3 Nylon 6 or Nylon 6-6 Mixed With Natural Fibers or   Rayon | 15 |
|  No. 4 Rayon Mixed With Cotton | 16 |
|  No. 5 Wool or Polyester Mixed With Cellulosic Fibers or Silk | 17 |
|  No. 6 Polyester or Acrylic Mixed With Wool | 18 |
|  No. 7 Natural Cellulosic Material and Rayon Mixed With   Acrylic, Modacrylic, and Polyester | 19 |
|  No. 8 Polyester Mixed With Olefin | 20 |
|  No. 9 Polyester Mixed With Acetate or Nylon 6,6-6 | 21 |
|  No. 10 Acrylic Fiber or Linear Spandex Mixed With Nylon or   Polyester | 22 |
| Microscopical Analysis |
|
|  Scope | 23 |
|  Summary of Method | 24 |
|  Sampling | 26 |
|  Apparatus | 25 |
|  Procedure | 27 |
| Keywords | 28 |
|
| |
|
| Table |
|
| |
| Chemical Methods for Analysis of Fiber Mixtures |  1 |
| Solubilities of Various Fibers in Solvents Used in Chemical |  2 |
| Fineness Ranges and Fiber Diameters of Various Textile Fibers |  3 |
| Density and Moisture Regain of Common Fiber Types |  4 |
1.4 The analytical procedures described in the test methods are applicable to the fibers listed in 1.2. The test methods are not satisfactory for the separation of mixtures containing fibers that fall within the same generic class but differ somewhat, either physically or chemically, from each other. These test methods are not satisfactory for the determination of bicomponent fibers.
Note 1: For other methods of analysis covering specific determinations, refer to: Test Methods D461, Test Method D584, Methods D885, Test Method D1113, Test Method D1334, and Test Method D2130. Methods for moisture are covered in Methods D885, Test Method D1576, Test Method D2462, Test Method D2495 and Test Methods D2654. For the determination of commercial weight, refer to Test Method D2494.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
