Boring post, boring topic (“Which is weft, which is warp?”)

As the title indicates, I find the nitpicking over weft v warp somewhat tedious. They are just words for the two sets of threads mutually at right angles, and even if I have confused the two – which I’m willing to concede – it would not make a jot of difference to the science. I could have called them wxxx and wyyy , or tweedledum and tweedledee, as I was saying earlier to Hugh Farey in a comment (now there’s a sterling fellow with a commendably open mind).

In fact, I did a quick internet search to check on Thibault Heimburger’s identification of weft and warp (page 17/24, pdf document).  The wiki entry on weaving is not an easy read, but my interpretation of it (see below) agreed with Thibault’s.  That was good enough for me. Life’s too short to get mired in mere  semantics.

As I promised Hugh, here are the graphics on which I based my decision.

Firstly, that wiki entry:

From wiki entry on “weaving”

Secondly, a close-up of an image area on the Shroud (Mark Evans/STERA), the one I used in a  previous posting, with my disputed labels for weft and warp.

Look at the Shroud graphic above. Observe that it is like viewing that previous  wiki diagram of a 3/1 twill from the opposite side. Then look at the text that accompanies the wiki diagram. Am I not correct in thinking that it is those HORIZONTAL threads that overlie 3 vertical threads that are the WARP threads?

My conclusion agrees with that of Thibault Heimburger. I may have differences with him over the nature of the Shroud image (scorch or not scorch) but I don’t doubt for one moment his admirable thoroughness in researching a topic before putting finger to keyboard (or pen to paper as we used to say). Maybe Thibault would be willing to explain how he arrived at his decision on weft and warp – which as I say happily concurs with my own.

Late addition (Thursday am) : for a contrary view, see this link, which states that each weft thread passes under three warp threads and then over one, which would (presumably) correspond with the white threads in the wiki diagram:

“The Turin Shroud is made of linen threads woven in a herringbone pattern of 3 under 1, i.e, each weft thread passes under three warp threads and then over one, under three and over one, etc. With each successive thread, the pattern is staggered by one thread. This happens 40 times in succession (11 cms) to give the weave its oblique aspect. Then there is a change of direction, which give the cloth its chevron or herringbone pattern. The total weight of the Shroud is 1.12 kg, and its average thickness is 0.3 mm, giving an average weight of 20 milligrammes per square centimetre.”

Supporting the above interpretation, you read this:

Definition: A fabric’s weft is made up of threads that run perpendicular to the length of fabric as it comes off the bolt. In other words, perpendicular to the selvage — those tightly bound edges that run along the length of fabric to keep it from fraying. You will see weft threads referred to as a fabric’s crosswise grain.

Confusing, isn’t it, given that the sources are not giving clear definitions or seem to adopt differing criteria?

Anyway, I’ve responded to the semantic nitpickers. It makes no difference to any of my conclusions as to whether the  blue or white colour-coded threads in that wiki diagram are warp or weft. My concern is purely with the scientific principles underlying image formation on linen... What is indisputable from the Shroud micrographs is that the image is mainly on the highest of three planes in the weave, representing those threads that pass over three disposed at right angles, then under one, similarly at right angles, then back over another three etc. It’s those “horizontals” with lengths at least three times the diameter of the largely recessed “verticals” which is where most of the action is, so to speak, re image capture and imprinting. Put more simply, the image is mainly on the most superficial threads of the weave. That fits nicely with thermal imprinting by intimate atom-to-atom contact with a hot inanimate template. I’ve yet to hear how that crucial superficiality can be explained by any credible alternative hypothesis (to say nothing of the signature light/dark reversal and encoded 3D information), certainly not any radiation model.

There is still only one game in town.  It’s called thermal imprinting, aka scorching.


About Colin Berry

Retired science bod, previous research interests: phototherapy of neonatal jaundice, membrane influences on microsomal UDP-glucuronyltransferase, defective bilirubin and xenobiotic conjugation and hepatic excretion, dietary fibre and resistant starch.
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