Optical and Physical Properties of Flax Fibers on Turin Shroud
From Ray Rogers’ FAQ:
Flax fibers look like small lengths of bamboo under a microscope.
The gross internal composition of a flax fiber is shown in the figure (after Cardamone).
The cellulose molecules in flax fibers are folded back and forth in a fairly regular arrangement, and they show the properties of crystallinity. The fibers are composed of closely packed "ultimate cells" of the fibrillar structure that are cemented together with holocellulose and lignin. You can see the ultimate cells under a microscope, and abraded fibers often show ultimate cells sticking away from the surface. These were the structures that were mistaken for "filamentous bacteria" by Garza-Valdes.
When you rotate the stage of a petrographic microscope with crossed polarizers while looking at a flax fiber, straight lengths change from black to colored every 45?. The fiber is birefringent and has an ordered structure. Most of the cellulose of the fibers is in a crystalline structure. In structures like flax, it is called a "fibrillar" structure.
McCrone ignored our agreements for work on the STURP sampling tapes: he stuck them all down to microscope slides. This made observations much harder; however, flax and cotton fibers can still be distinguished by their indexes of refraction.
Crystallographic observations must be made on the specific fibers that reach extinction at the same angle as the tape (while everything is black). The index of refraction of a normal linen fiber parallel to its length is nearly identical to that of the adhesive on the sampling tapes (it nearly disappears). That index is very close to 1.515. The index across the fiber is appreciably lower than the adhesive. The indexes of refraction and crystallinity of image fibers are identical to unaffected fibers. Bent, crushed, or otherwise damaged fibers show strain dichroism and will give an erroneous index. Most flax fibers show intense birefringence colors when they are viewed at a 45º angle from the plane of polarization of the microscope.
Cotton has a low birefringence, usually appearing white (first-order white), and it is a thin, wide tape that shows periodic reversals (twists).
Optical and Physical Properties of Flax Fibers on Turin Shroud
How do you know that the image was not a scorch?
From Ray Rogers’ FAQ
As discussed in (Why radiation did not cause images), the crystallinity of the flax fibers in all of the parts of the Shroud that were not scorched has not been significantly degraded.
The Arrhenius Law describes the effect of temperature on rate constants for all consistent chemical reactions, as follows:
k = Ze-E/RT
where k is the rate constant at any specific temperature, Z is the Arrhenius pre-exponential (related to the probability that any specific molecule(s) will react), E is the Arrhenius activation energy, R is the gas constant, and T is any specific, constant absolute temperature (degrees Kelvin). If the image were a scorch or any part of the Shroud had been heated enough to make significant changes in the rates of decomposition of any of its components, we would see changes in the structure of the flax fibers and blood. The blood still evolves hydroxyproline on mild heating, and the cellulose crystals are largely undistorted. Image and control fibers show identical crystal properties. The image is not a scorch. The cloth was not heated, not even boiled in oil.
How do you know that the image on the Shroud of Turin was not painted?
From Ray Rogers’ FAQ
The primary goal of STURP was to test the hypothesis that the Shroud’s image was painted, as claimed by Bishop d’Arcis in 1389. If it had been painted, some colored material had to be added to the cloth, but the colored material would have gone through the fire of 1532. The pigments and vehicles would have suffered changes in response to the heating, the pyrolysis products, and the water used to put the fire out. No changes in image color could be observed at scorch margins.
We tested all pigments and media that were known to have been used before 1532 by heating them on linen up to the temperature of char formation. All of the materials were changed by heat and/or the chemically reducing and reactive pyrolysis products. Some Medieval painting materials become water soluble, and they would have moved with the water that diffused through parts of the cloth as the fire was being extinguished. Observations of the Shroud in 1978 showed that nothing in the image moved with the water.
The Shroud was observed by visible and ultraviolet spectrometry, infrared spectrometry, x-ray fluorescence spectrometry, and thermography. Later observations were made by pyrolysis-mass-spectrometry, lasermicroprobe Raman analyses, and microchemical testing. No evidence for pigments or media was found.
Your eye sees colors when the surface absorbs some wavelengths of light and reflects others. A red surface absorbs all visible wavelengths other than red. Each chemical compound absorbs wavelengths that are characteristic of its chemical structure. The best way to determine the properties of a color is by measuring its spectrum. Reflectance spectrometry was one of the most important contributions of the STURP observations.
The reflectance spectra in the visible range for the image, blood, and hematite are shown in the figure. The image could not have been painted with hematite or any of the other known pigments. The spectrum of the image color does not show any specific features: it gradually changes through the spectrum. This proves that it is composed of many different light-absorbing chemical structures. It has the properties of a dehydrated carbohydrate.
There is no evidence for significant amounts of any of the many pigments and/or dyes that could have been used to paint or touch up the blood stains. We had considered and studied Tyrian purple (6,6′-dibromoindigo) and Madder root dye on an aluminum and/or chromium mordant as well as cinnabar (mercuric sulfide) and ferric oxide pigments.
During and before the 14th Century, gold metal was the most important yellow. That would easily be detected by x-ray fluorescence. Other pigments in common use were yellow ocher (hydrated Fe2O3), burnt ocher (hematite Fe2O3) and other ochers, orpiment (As2S3), realgar (AsS), Naples Yellow (Pb3[SbO4]), massicot (PbO), and mosaic gold (SnS2). Organic dyes included saffron, bile yellow, buckthorn, and weld. Madder root began appearing in Europe from the Near East about that time. Many of the dyes required mordants, which are hydrated oxides of several metals (e.g., aluminum, iron, and chromium). In order to produce the shadings observed in the Shroud’s image, the concentrations of pigments would have to vary across the image. No variations in any pigment were observed by x-ray fluorescence spectrometry. The image was not painted with any inorganic pigment of an appropriate color.
Image on Shroud of Turin not Painted-Spectometry-Fluorescence
Attempts to reproduce the Shroud
Many attempts were made to show how a forger might have created the image. It was, some said, a fairly conventional painting. No, argued Emily Craig, a forensic anthropologist, it was some sort of portrait in dust that was transferred to a piece of cloth by rubbing the cloth placed over the portrait. No, said others, it was a medieval photograph, perhaps made by Leonardo da Vinci. Room size cameras were created to show that such a device might have been invented. A life-size photograph of a statue was made on cloth. It was, as far as logic went, like making a printing press and printing a Bible to show that Leonardo might have invented printing. Nathan Wilson, an English teacher at a small mid-western college, very much convinced that the shroud was fake because it contradicted his literal reading of the Gospel of John, created an interesting shroud-like image by sun-bleaching unbleached linen with a mask painted on a piece of glass. But it, too, failed to reproduce many of the shroud’s features, in fact most of them. In October of 2009, Luigi Garlaschelli, a professor of organic chemistry at the University of Pavia, Italy, created an image that looked a lot like the shroud. It was a combination of body rubbing and bas-relief rubbing. He used a pigment laced with acid. When he washed the pigment away, the acid had etched an image on the cloth’s fibers. It, too, fails to reproduce the complex image on the shroud.
Nonetheless, in each case, the media reported that the shroud had been reproduced, failing to note that they had previously reported something else and instead writing that until now no one had been able to explain how the images might have been formed. Rebuttal to these claims, no matter how scientifically or logically justified, got scant attention.
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