Middle East vs. Middle Ages: Is it an historical clue to the shroud’s age and provenance?
How was linen bleached in Europe during the Middle Ages as compared to how linen
was bleached in the Middle East 2000 years ago?
In a Frequently Asked Questions (FAQ), a document he published in 2004, Raymond Rogers provided the following answer:
FAQ 7: Why are there bands of different coloured (sic) linen throughout the Shroud, and what do they prove about image-formation mechanism?
Bands of slightly different color can be seen in Shroud photographs. They are most visible in ultraviolet-fluorescence photographs (see Hands UV).
Both warp and weft yarns show this property. Some areas show darker warp yarns and some show darker weft yarns. In some places bands of darker color cross. In other places bands of lighter color cross. The effect is somewhat like a plaid.
All of the bleaching processes used through history remove lignin and most associated flax impurities (e.g., flax wax and hemicelluloses). The more quantitative the bleaching process the whiter the product. The bands of different color on the Shroud are the end result of different amounts of impurities left from the bleaching process.
Anna Maria Donadoni, a curator at the Museum of Egyptology in Turin, pointed out locations where batches of yarn ended in the weave and new yarn had been inserted in order to continue weaving. The yarn ends were laid side by side, and the weave was compressed with the comb. The ends are often visible, and the overlaps correspond to zones of different color in the weave. The different batches of yarn show different colors.
Where darker bands of yarn intersect image areas, the image is darker. Where lighter bands intersect an image area, the image appears lighter. This proves that the image color is not a result of reactions in the cellulose of the linen. Some impurities on the surface of the different batches of yarn produced the image color. This observation is extremely important when tests are being made on image-formation hypotheses. If image color is not simply a result of color formation in the cellulose of the linen fibers, image formation must be a much more complex process than we originally thought.
Linen in the first century, in the Middle East, was hank bleached. It was an imprecise method resulting in some yarn being whiter and some slightly darker or off-white. This resulted in variegated patterns in linen cloth as different hanks of yarn were fed into the loom. See contrast-enhanced photograph of variegated patterns
Some of the bands of different shades of white (now perhaps more yellowed and browned with age) are narrow and some are quite wide.
The variegation, or banding as it is sometimes called, produces a visual background noise pattern that alters the way we see things on the Shroud.
The face of the man of the shroud is gaunt. That is a common observation. The nose is narrow, eye sockets exceedingly deep, the hair seems to fall straight. At least that is how is seems. Look carefully and you will see that the gaunt appearance is the result of dark vertical bands on each side of the face on the outer part of the cheeks. There are faint, less perceptible bands on each side of the nose and a horizontal band across the eyes, as well.
Fourier transform filters can be used to mathematically find these bands and minimize their effect. Notice how filtering seems to change the shape of the face and nose and makes the eyes look more normal. The hair is less forward. It doesn’t actually change the shape of the face; it merely minimizes the background noise and allows details to emerge.
It is very unlikely that the linen cloth used for the Shroud was produced in medieval Europe. Such cloth was field bleached after weaving. Medieval European linen was not hank-bleached. Instead, the woven cloth was soaked in hot lye solution, washed, soaked in sour milk and washed again. Other ingredients, like cattle urine were sometimes used, as well. Following this treatment the cloth was spread out in fields in the sun. This process eliminated variegation.
To my way of thinking banding provides strong evidence that the cloth is not medieval. It also provides a strong argument against opaque imaging methods. That would certainly be some paints, the metals produced from photosensitive salts. I don’t know about scorching. I rather suspect that it would not prohibit very light scorching.
Other previous postings about banding: