Methods for Dye, Yarn, and Fiber Analysis: Textile Certification

(Various dye analysis methods are compared)

Navajo Textile Certification would involve:

  1. Visual inspection: Style and art history are analyzed, as well as color and the use of pattern or design are explored to understand technical elements and materials the weaver employed. 

  2. Microscopic warp examination: The warp is constructed as a separate complete textile before the weft is added. Materials and techniques vary for maintaining strength and form in terms of the textile’s strength and tension i.e., can it lay flat or is it curling up? Re-tensioning of the warp may have occurred during weaving. Occasionally weavers added materials to different areas of the textile’s warp. Micro-photographs (60X) are taken to document warp yarn variations. Photographic evidence for fiber identification is also obtained at a higher magnification (200X-400X).

  3. Microscopic (60X) weft yarn examination: Yarns are examined to determine consistency of material use or modification including, blending by carding, raveling, and commercial yarns or hand spun yarns. Micro-photographs are taken to illustrate and supply evidence for identification of yarn differences.

  4. Microscopic (200X-400X) weft fiber examination: A second microscope with higher magnification is used to analyze the fibers on a slide from a specific yarn sample. Identification of the fiber and comparison with other fibers from the same textile and fiber standards are made. Micro-photographs are taken to illustrate and supply evidence for identification of fiber differences.

  5. Sample extraction: Samples to be taken are determined from assessing 1-4 above. Three to four milligram extractions of yarn samples are made using a microscope and the textile is not visually damaged. You can not find where the samples were taken.

  6. Mapping: *When possible* A Photostat copy or image that can be used as a map of each textile in order to locate the area where each sample is taken. Measurements from the bottom and side are made to identify the spot where the sample was taken. Each side of the textile is determined so measurements and mapping can be accurately reproduced. Triangulation of sample location from identified corners on a specific side of the weaving is noted.

  7. Sample preparation and dye extraction: Many textiles are contaminated with soaps, dyes and stabilizers, or pesticides and even poisons such as arsenic. The sample needs to be cleaned and tested for any residue. The cleaned sample is then subjected to a process of chemical extraction of the dyes. The dyes in the extraction solution must be converted from the frequently acidic pH to a neutral pH before injection into the HPLC testing equipment.

  8. Running the sample: The HPLC equipment must be calibrated and in equilibrium before a dye standard can be run. After a cochineal standard yields the expected chromatographic and spectral results an unknown sample is injected.

  9. Analysis: The macro observations of style, materials, and techniques used are integrated with the micro analysis and the HPLC dye testing results. The dye analysis is linked to species specific natural dye insects or plants and synthetic chemical dyes identified in the Color Index with their discovery dates. Chromatographic and Spectrographic printed reports are generated from each dye run and supplied as evidence for dye identification.

  10. Synthesis: The results of all the microscopic observations and HPLC dye analysis are put into perspective by incorporating the information with published literature on the subject. Suggestions, observations of supportive or divergent results from previous assumptions or examinations and conclusions about the textile including associations with patent dates and Art Historical categories and classifying techniques are documented. 

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Call Casey Reed@505-344-8492