In 1973, Gilbert Raes, a textile expert, was granted permission to excise a small piece of the Shroud for further examination. This piece he removed included what was 1) assumed to be part of the whole or main part of the cloth (40 mm x 13 mm), 2) a side strip (40 mm x 10 mm) and 3) some sewing thread that joined the two pieces together.
In the first part, assumed to be representative of the whole cloth, he found "in some of the preparations from the warp as well as from the weft of Piece 1, traces of cotton fibers were observed.” He identified the cotton as Gossypium herbaceum, a variety unique to the Middle East. This led some to speculate that the cloth had been woven on looms, in the Middle East, that were also used for cotton weaving and that the "trace of cotton" were contamination. Others concluded, perhaps more correctly, that the cotton was indeed intentionally used along with flax fibers during spinning of the yarn.
The unfortunate assumption, however, was that the yarn in the Raes sample was representative of the whole cloth. Archeologist William Meacham had put it this way in 1983:
The cloth itself has been described (Raes 1976) as a three-to-one herringbone twill, a common weave in antiquity but generally used in silks of the first centuries A.D. rather than linen. The thread was hand-spun and hand-loomed; after ca. 1200, most European thread was spun on the wheel. Minute traces of cotton fibers were discovered, an indication that the Shroud was woven on a loom also used for weaving cotton. (The use of equipment for working both cotton and linen would have been permitted by the ancient Jewish ritual code whereas wool and linen would have been worked on different looms to avoid the prohibited "mixing of kinds.") The cotton was of the Asian Gossypum herbaceum, and some commentators have construed its presence as conclusive evidence of a Middle Eastern origin. While not common in Europe until much later, cotton was being woven in Spain as early as the 8th century and in Holland by the 12th.
When Ray Rogers examined the fibers in 2002, he confirmed the existence of the cotton fibers and that it was indeed embedded. But as Rogers noted, from later studies on the whole shroud, there was no evidence of cotton fibers anywhere else. Rogers also found spliced threads and dyestuffs in the Raes samples and noted that these were not found anywhere else on the Shroud. This suggested some sort of alteration or disguised mending.
Rogers also discovered that fibers in the Raes material contained less lignin than the rest of the shroud. Lignin is a chemical compound found in plant material including flax. The most plausible explanation for this difference was that material in this area contained threads that had been bleached more efficiently. It was already known from the shroud’s faint variegated appearance, commonly referred to as banding, that the shroud’s thread was probably bleached before weaving, probably with potash. This is not an exacting method and thus some hanks of yarn were whiter than others. As the cloth aged and naturally yellowed, the variegation became more pronounced, as can be seen in contrast-enhanced photographs. This form of ancient bleaching removed very little lignin.