What caused Ray Rogers to change his mind about the carbon dating?
Having been prompted to re-examine the region of the carbon dating sampling, in order to disprove the Benford and Marino's suggestion that the carbon dating had been affected by an "invisible reweaving, Ray Rogers began a new, close examination of actual material from the shroud. In collaboration with Anna Arnoldi of the University of Milan, Rogers wrote a paper arguing that the repair was a very real possibility.
The material Rogers studied was from an area directly adjacent to the carbon 14 sample, an area known as the Raes corner. Rogers discovered a carefully spliced thread. This was unexpected and and completely inexplicable. During actual weaving of the linen cloth, whenever a new length of thread had been introduced into the loom, the weavers had simply laid it in next to the previous length rather than splicing. This was a common practice. Rogers and Arnoldi wrote:
[The thread] shows distinct encrustation and color on one end, but the other end is nearly white . . . Fibers have popped out of the central part of the thread, and the fibers from the two ends point in opposite directions. This section of yarn is obviously an end-to-end splice of two different batches of yarn. No splices of this type were observed in the main part of the Shroud.
Rogers also found alizarin, a dye produced from Madder root. The dye appeared to have been used to match new yarn to older age-yellowed yarn. In addition to the madder dye, Rogers found a gum substance that was possibly gum Arabic, and a common mordant, alum. This seemed to be clear evidence of a carefully crafted repair, intended to not be noticeable.
Rogers confirmed the existence of embedded cotton fibers in the area of the carbon dating sample, while noting that such cotton fibers are not found in other samples from anywhere else on the shroud. Gilbert Raes, a textile expert, had first found cotton fibers in 1973. He assumed, and everyone assumed at the time, that this was representative of the whole cloth. It turns out that it was not. Thousands of fiber samples taken from the main part of the Shroud reveal no cotton, whatsoever.
Rogers also discovered that fibers in the Raes area (the corner from which the carbon dating material had been taken) contained significantly less lignin than the rest of the shroud. Lignin is a chemical compound found in plant material including flax, the plant from which linen fibers are sourced. 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 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. This did not resemble medieval linen that was field bleached.
Finally, and significantly, Rogers found that vanillin had been depleted from the main body of the Shroud but not from the mended corner. This could only mean that the carbon dating sample was not representative of the whole cloth and that the cloth was much older.
- What is the significance of Vanillin in understanding the age of the Shroud?
- What prompted Ray Rogers to re-examine the carbon dating problem?
- What did the Thermochimica Acta article say?
- Who was Ray Rogers?