From an article, The Turin Shroud in a blog called Bad Archaeology (two guys) we find:
It was in the documentary’s omissions that the greatest faults lay. The voice-over stated that the image is not painted, giving the impression that nobody could explain the colouring other than that it’s a “degradation of the cellulose” in the linen fibres. That’s not quite correct. What is seen on the shroud is a chemical darkening of a starch and polysaccharide coating on some of the fibres: it’s not the fibres themselves, but something applied to them after manufacture. In other words, pigment. And if that’s not paint, I really don’t know what is. One of the members of the STURP team, Walter McCrone, concluded during the study that the image was painted using red ochre and vermillion pigments. The programme didn’t mention him or his conclusions!
. . .
The scientists at the radiocarbon laboratories noted contamination of the samples with cotton, while McCrone had already drawn attention to the mixture of cotton and linen. This means that they were able to deal with it. They recognised the cotton and removed it, dating the linen fibres, which is what they were asked to do. The preparation of samples for dating involves rigorous cleaning to remove potential contaminants, such as these stray cotton fibres. There is no reason to suspect that the three laboratories undertaking the dating did not do their basic cleaning, especially as they had spotted the contaminants.
The programme brought up the old claim that the image on the shroud somehow encodes three-dimensional data and, using the same computer program used to create a three-dimensional image of the face on the shroud, showed that it does not work with photographs. How dishonest! We’re not dealing with a photograph on the shroud but with a painted image. The comparison should have been with a painting. Talk about prejudged conclusions! Besides, if we’re dealing with an image produced by draping a cloth over a corpse, it ought to be far more three-dimensional than we see: where are the sides of the body that the cloth would have touched? The fact that they aren’t there is good evidence that the image is painted.
Extraordinarily bad archaeology being practiced here fellows. Did they really say?
What is seen on the shroud is a chemical darkening of a starch and polysaccharide coating on some of the fibres: it’s not the fibres themselves, but something applied to them after manufacture. In other words, pigment. And if that’s not paint, I really don’t know what is.
It’s not paint. Did you mention that the coating is 200 to 600 nanometers thin? Paint that! Did you mention some real science used to test for paint? Ray Rogers is quoted below:
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.
Did you say the labs detected cotton and removed it? Did they ask why cotton was there? Cotton isn’t the contaminant here. It suggests the possibility of other contaminants. Did they do a chemical analysis of the samples? Madder root dye, aluminum products, gum were subsequently found. They overlooked that. Cotton was a clue that the sample might have material intrusions from repairs. The repairs might have been made with newer linen with cotton spun in among the linen fibers to hold dye needed to make newer cotton look old. Evidence suggests that is so. Did you mention that the test results fail basic statistical tests for sample homogeneity? Did you mention that what was tested was chemically unlike the whole cloth. Did you mention that
the cloth contains measurable vanillin but that the carbon dating samples do not the cloth does not contain measurable vanillin but that the carbon dating samples do? (Corrected)
Good archaeology means considering all the facts, not just those that are convenient.
You did say, also:
In the event, three laboratories were chosen (Arizona, Oxford and Zürich) and asked to perform several tests on each of four samples taken from different parts of the cloth. . . .
No, they did not take samples from different parts of the cloth. One sample from one corner was cut. Part of it was divided into three roughly equal portions for each of the labs. They then made further divisions. Bad archeology includes bad factual statements, does it not?
Do we need to review this?
The programme brought up the old claim that the image on the shroud somehow encodes three-dimensional data and, using the same computer program used to create a three-dimensional image of the face on the shroud, showed that it does not work with photographs. How dishonest! We’re not dealing with a photograph on the shroud but with a painted image.
Maybe on the television program in question someone compared the shroud image to a photograph. But it has also been compared to numerous painted images. A little basic research would have revealed this. It is irrelevant anyways. It shows a complete lack of understanding about the 3D properties of the shroud image. You might want to check out The so-called 3D Encoding of the Shroud.