Hemp fiber identification project
Robert C. Clarke
International Hemp Association
Since 1995, the
International Hemp Association (IHA) has solicited assistance from researchers
to establish protocols for the identification of Cannabis hemp fibers.
Our interest was first piqued in 1995, when we visited Dr. Elena Mikolaychuk at
the Hermitage Museum in St. Petersburg, Russia to view Cannabis remains
recovered in the late 1940s from a Scythian era (ca. 2400 BP) tomb near
Pazyryk (Rudenko 1970). Dr. Mikolaychuk showed us well-preserved Cannabis
seeds and some unidentified (possibly hempen) textiles and asked if we would
find experts to determine their fiber content. We agreed, and she provided the
IHA with three tiny samples taken from different parts of a nearly intact shirt
and a fourth sample from the sleeve portion of a second garment.
The identification of fibers in textiles recovered from archeological contexts is often complicated by their decomposition during burial. Although the Pazyryk remains were most likely continually frozen in ice from soon after the time that they were entombed until they were recovered, and are relatively well preserved, positive identification has proven problematic. These samples have now been studied by both light and scanning electron microscopists specializing in fiber identification and we hope to present positive fiber identification of the Pazyryk textiles in the near future.
Determinations of the hemp fiber content of textiles is also required in other applications. Cultural artifacts in museums are often classified by material type, but the identity of plant fibers used in their construction is rarely recorded. Ethnobotanical researchers working with museum collections require positive fiber identifications before accessions can be included in research projects and publications. The largest problem with positive determination of fiber content in cultural artifacts is the wide choice of bast and leaf fibers that could possibly have been used to make the artifact. Researchers investigating potentially hempen artifacts must know whether they are working with Cannabis hemp. Determining whether an artifact contains hemp fibers is quite a different matter than positively identifying which other fibers it may contain. Accurate fiber identification relies on comparisons of unknown samples with extensive collections of voucher samples taken from botanical specimens. The IHA has assembled stem samples of various bast fiber species collected in several locations and these samples will be made available to qualified investigators.
Buyers and sellers of modern pure and blended hemp textiles require accurate identification of hemp fiber content for quality assurance. Few independent or government analytical laboratories will perform textile fiber content analyses, and none specialize in bast fiber analysis. Analyses by independent laboratories can be very costly, depending on whether the results list only the presence or absence of hemp fibers, the additional fibers are identified, and/or the percentages of the various fibers are determined. Analysis costs are high largely because none of the independent laboratories analyze only textile fibers and therefore each analysis bears the cost of setting up the analysis protocol. A small laboratory dedicated to vegetable fiber analysis should be able to perform analyses at a lower price. The treatment of the textiles, such as dying, bleaching, softening or other finishing techniques may also alter the appearance of the fibers and complicate analyses. This problem is most evident in modern fabrics, but also occurs in traditionally processed hand-made fabrics. The IHA has collected many swatches of historical and contemporary hemp fabrics for use as a reference collection.
The Hemp Industries Association (HIA) has worked for several years to establish an industry-wide certification program for hemp textiles and garments. One of the major obstacles has been the lack of affordable textile analysis by impartial laboratories. Most expertise in bast fiber analysis resides in hemp producing nations such as China, Hungary, Poland and Romania. Laboratories in these countries may have a vested interest in the results of hemp textile analyses. Therefore, importers and wholesalers would prefer to rely on a single laboratory located in a western nation that does not produce hemp textiles.
Several sources give descriptions and measurements of Cannabis hemp and other fibers. Mauersberger (1947) reports fiber measurements, descriptions and chemical tests for many of the fibers of commerce. Catling and Grayson (1982) provide detailed descriptions of several vegetable fibers and in-depth comparisons of the anatomical fiber features between several fiber species. Rahman and Sayed-Esfahani (1979) used a scanning electron microscope to characterize the surface changes in hemp fibers during various stages of processing. However, none of these researchers have published any data for archeological specimens or samples of hemp textiles processed by traditional methods. Ryder (1993) reported on the identification of hemp fibers recovered from a Bronze Age site in Scotland, based mostly on fiber diameter.
Dorothy Catling of the University of Durham in England will teach a short course on vegetable fiber identification in July and the IHA will finance a member to attend. We hope that the course will lead to additional training to perfect the particular skills required for bast fiber identification. The HIA can request this trainee to set up an official hemp fiber certification program.
Catling, Dorothy and John Grayson 1982 Identification of Vegetable Fibers. Chapman and Hall, London and New York:18-23.
Mauersberger, Herbert R. (Ed.) 1947 Matthews’ Textile Fibers. 5th Ed.: John Wiley & Sons: New York:305-368.
Rahman, M. M. and M. H. Sayed-Esfahani 1979 Study of the surface characteristics of hemp fibres using scanning electron microscopy. Indian Journal of Textile Research 4:115-120.
Rudenko, Sergei I. 1970 Frozen Tombs of Siberia, the Pazyryk burials of iron age horsemen. Univ. of Calif. Press, Berkeley and Los Angeles:34-37, 62, 284-85.