Banding

The linen threads on the shroud do not all have the exact same color. The threads have been produced in batches and because each batch has slight differences with another, it results in the banding effect on the cloth.

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.

https://www.shroud.com/pdfs/rogers5faqs.pdf

Another interesting feature is the presence of numerous dark (pale in the photographic
negative) warp threads that run for some distance through the Shroud and cross from
image to non-image areas. A good example runs through one side of the face, across the
eye and forehead into the hair. These darker threads indicate that, even though the cloth
was piece bleached, the yarns must also have been at least part bleached before weaving,
probably in hank form.
Dealt with in hank form, the yarns would not have been similarly and evenly bleached
throughout their lengths. Although the cloth would be bleached again after weaving, this
treatment evidently failed to even-up the differences in shade between and within the
individual yarns.

https://www.shroud.com/pdfs/ssi06part6.pdf

Medieval linen do not typically exhibit banding in threads.

Commercial production of linen started during Medieval times, and the linen looks much
different than the Shroud. Medieval linen was spun to great lengths on the spinning wheel,
and it was bleached as the cloth. Most commercial bleaching took place in “bleach fields” in
the Low Countries, the genesis for the name “Holland cloth” that is applied to the backing on
the Shroud. Considerable material was lost during the bleaching process, and the newer
linens are less dense, as can be seen with the Holland cloth. The newer linens are also
homogeneous. They do not show bands of different thread in the weave.

https://www.shroud.com/pdfs/rogers10.pdf

Banding is compatible with 1st century weaving.

It should be recognized that not all Shroud locations show lignin to the same extent. This is not
surprising, because bands of thread in both the warp and weft are observed to have slightly
different densities of colour. This fact supports the hypothesis that the Shroud was woven from
linen made by the ancient technology described by Pliny the Elder. Pliny described thread made
on a hand spindle whorl that was bleached in separate batches before being used in the weaving
operation.

https://www.shroud.com/pdfs/n54part6.pdf

So, the evidence of banding on the cloth makes it more likely it is a first century cloth than a medieval cloth.