(The text below is made up of quotes from the sources below. The color of the text matches the color of its source.)

Turin Shroud Center of Colorado (8/6/10) http://www.shroudofturin.com/shroud.html
Wikipedia (7/12/10)http://en.wikipedia.org/wiki/Shroud_of_Turin
Thoughtful skeptical inquirer (7/16/10) http://www.skepticalspectacle.com/
Skeptics Dictionary (7/17/10) http://www.skepdic.com/shroud.html
Story Guide 2010 (7/19/10)http://www.shroudstory.com/
Shroud Mania (7/30/10) http://blog.ecso.org/2010/04/shroud-of-turin-mania/



Carbon Dating

  1. In 1988 a radiocarbon dating test was performed on small samples of the shroud. The laboratories at the University of Oxford, the University of Arizona, and the Swiss Federal Institute of Technology, concluded that the sample they tested dated from the Middle Ages, between AD1260 and AD1390.[6][7] The samples tested have since been questioned and two peer-reviewed articles have contended that they may not be representative of the whole shroud.[8][9][10][11][12]
  2. After years of discussion, the Holy See permitted radiocarbon dating on portions of a swatch taken from a corner of the shroud. Independent tests in 1988 at the University of Oxford, the University of Arizona, and the Swiss Federal Institute of Technology concluded that the shroud material dated to 1260-1390 AD, with 95% confidence.[6] This 13th to 14th century dating matches the first appearance of the shroud in church history,[31] and is somewhat later than art historian W.S.A. Dale's estimate of an 11th century date based on art-historical grounds.[78] Criticisms have been raised regarding the sample taken for testing (it may have come from medieval repair fragments), although not the quality of the radiocarbon testing itself.[79][80] [81]
  3. Apparently, the first historical mention of the shroud as the "shroud of Turin" is in the late 16th century when it was brought to the cathedral in that city, though it was allegedly discovered in Turkey during one of the so-called "Holy" Crusades in the so-called "Middle" Ages. In 1988, the Vatican allowed the shroud to be dated by three independent sources--Oxford University, the University of Arizona, and the Swiss Federal Institute of Technology--and each of them dated the cloth as originating in medieval times, around 1350.
  4. The shroud allegedly was in a fire during the early part of the 16th century and, according to believers in the shroud's authenticity, that is what accounts for the carbon dating of the shroud as being no more than 650 years old. To non-believers, this sounds like an ad hoc hypothesis.
  5. Did not carbon 14 demonstrate that the Shroud was medieval? Could it possibly be wrong? Carbon 14 dating, the skeptical inquirer knows, is useful for dating material going back about 50,000 years. And it is extraordinarily accurate for material less than 10,000 years old. Yes, there can be problems with contamination. But the labs that do this work do a very good job of removing contamination with combinations of alkaline and acidic baths. And yes, absolute precision is impossible. In the Shroud carbon 14 samples there was less than one carbon 14 atom for every trillion or so carbon 12 and carbon 13 atoms. But the quantity of material was sufficient and the methods accurate enough to estimate that the material tested produced a statistically certain range of dates: 1260 to 1390 CE. Even so, there might be a reason to suspect some error.
  6. The suggestion that the 1532 Chambery fire changed the date of the cloth is ludicrous. Samples for C-dating are routinely and completely burned to CO2 as part of a well-tested purification procedure. The suggestions that modern biological contaminants were sufficient to modernize the date are also ridiculous. A weight of 20th century carbon equaling nearly two times the weight of the Shroud carbon itself would be required to change a 1st century date to the 14th century (see Carbon 14 graph). Besides this, the linen cloth samples were very carefully cleaned before analysis at each of the C-dating laboratories.*
  7. There have been claims that a biological polymer was growing on the Shroud and that this could have affected the date. Not so! The National Science Foundation Mass Spectrometry Center of Excellence at the University of Nebraska, using highly sensitive pyrolysis-mass-spectrometry, could not detect any such polymers on Shroud fibers.  Furthermore, it is well known that a biopolymer product would show the same carbon age as the Shroud because the organism would use fixed carbon from the cellulose fibers and not from the atmosphere. Similar claims that a scorching fire in 1532 might have altered the carbon 14 isotope ratios are scientifically unsustainable. The skeptical inquirer is right to pooh-pooh such ideas.
  8. But as the skeptical inquirer knows, material intrusion is a potential problem in carbon 14 dating. A classic example is the dating of peat from ancient bogs. Miniscule roots from much newer plants get entangled in the peat -- some roots having decomposed into newer peat -- and this will distort the results. Could something like this have affected the results of dating of the Shroud? As it turns out, chemical and visual analyses, done in just the last two years, show unmistakable proof of material intrusion of new linen fibers -- enough material by some estimates to make a 1st century cloth seem medieval. The discovery of alizarin dyes (from Madder root), a hydrous aluminum oxide mordant and plant gum along with twisted-in cotton fibers and spliced threads in the carbon 14 sample region shows that the sample area was discretely repaired. These substances are not found anywhere else on the Shroud. Shroud of Turin Story Breaking News
  9. New Information in 2008: A team of nine scientists at the Los Alamos National Laboratory has confirmed that the carbon dating of the Shroud of Turin is wrong. See Shroud of Turin for Journalists, Fact Check at Shroud of Turin Blog & Ohio State University Shroud of Turin Conference
  10. The skeptical inquirer knows about decomposition kinetics. He knows that the cloth is linen. Each thread of the cloth is made up of roughly a hundred fibers from a flax plant. The skeptical inquirer knows about lignin, a complex polymer compound, one of the constituents of flax fibers. He knows that lignin's chemical composition changes over time. He knows that if a microchemical test for vanillin in lignin is negative that the cloth is more than 1300 years old, twice the age that the carbon 14 dating estimated. Clues from vanillin showed something was wrong in the carbon 14 tests. Something was very wrong.
  11. The big issue was always the carbon 14 dating that seemed to show that the Shroud of Turin was medieval. Researchers, who were not experts in radiocarbon dating, but nonetheless convinced the Shroud of Turin was authentic, tried to explain why the scientific dating was incorrect. These explanations – one was that a fire in 1532 changed the age of the Shroud, another was that a bioplastic-polymer growing on the Shroud contaminated the sample – lacked scientific credibility. Scientists, who were experts in radiocarbon dating, rejected these explanations.
  12. Read: Biggest Radiocarbon Dating Mistake Ever
  13. In January, 2005, things changed.  An article appeared in a peer-reviewed scientific journal Thermochimica Acta, which proved that the carbon 14 dating of the Shroud of Turin was flawed because the sample used was invalid. Moreover, this article, by Raymond N. Rogers, a well-published chemist and a Fellow of the Los Alamos National Laboratory, explained why the Shroud of Turin was much older. The Shroud of Turin was at least twice as old as the radiocarbon date, and possibly 2000 years old. 
  14. Peer-reviewed scientific journals are important. It is the way scientists normally report scientific findings and theories. Articles submitted to such journals are carefully reviewed for adherence to scientific methods and the absence of speculation and polemics. Reviews are often anonymous. Facts are checked and formulas are examined. The review procedure sometimes takes months to complete, as it did for Rogers. 
  15. It was Nature, another prestigious peer-reviewed journal, that in 1989, reported that carbon 14 dating ‘proved’ the shroud was a hoax. Rogers found no fault with the article in Nature. Nor did he find fault with the quality of the carbon 14 dating. He defended it. What Rogers found was that the carbon 14 sample was taken from a mended area of the Shroud that contained significant amounts of newer material. This was not the fault of the radiocarbon laboratories. But it did show that the carbon dating was invalid.  
  16. Immediately after the publication of Rogers’ paper, Nature published a commentary by scientist-journalist Philip Ball. "Attempts to date the Turin Shroud are a great game,” he wrote, “but don't imagine that they will convince anyone . . . The scientific study of the Turin Shroud is like a microcosm of the scientific search for God: it does more to inflame any debate than settle it.”  Later in his commentary Ball added, “And yet, the shroud is a remarkable artifact, one of the few religious relics to have a justifiably mythical status. It is simply not known how the ghostly image of a serene, bearded man was made.” 
  17. Ball, who understood the chemistry of the Shroud of Turin images, rejected a notion popularized by conspiracy theorists that Leonardo da Vinci created the Shroud's image using primitive photography. He called the idea flaky. He also debunked the sometimes reported speculation that the image was “burned into the cloth by some kind of release of nuclear energy” from Jesus’ body. This he said was wild.
  18.  Almost all serious Shroud of Turin researchers agree with Ball on these points. When flaky and wild ideas appear in newspaper articles or on television, as they often do, scientists cringe. Rogers referred to those who held such views as being part of the “lunatic fringe” of Shroud research. But Rogers was just as critical of those who, without the benefit of solid science, declared the Shroud of Turin a fake. They, too, were part of the lunatic fringe.
  19.  The idea that the Shroud of Turin had been mended in the area from which the carbon 14 samples had been taken had been floating around for some time. But no one paid much attention. In 1998, Turin’s scientific adviser, Piero Savarino, suggested, “extraneous substances found on the samples and the presence of extraneous thread (left over from ‘invisible mending’ routinely carried on in the past on parts of the cloth in poor repair)” might have accounted for an error in the carbon 14 dating. Longtime shroud researchers Sue Benford and Joe Marino independently developed the same idea and explored it with several textile experts and Ronald Hatfield of the radiocarbon dating firm Beta Analytic. The art of invisible reweaving, Benford and Marino discovered, was commonly used in the Middle Ages to repair tapestries. Why not the shroud, they thought? They believed they saw evidence of it.
  20. But the skeptically minded Rogers did not agree. He had already debunked every other argument so far offered to explain why the carbon 14 dating might be wrong. According to Ball, “Rogers thought that he would be able to ‘disprove [the mending] theory in five minutes’.” Instead he found clear evidence of discreet mending. He also showed, with chemistry, that the shroud was at least thirteen hundred years old. And he proved, beyond any doubt, that the sample used in 1988 was chemically unlike the rest of the shroud. The samples were invalid. The 1988 tests were thus meaningless. 
  21. In words that seem strange in a scientific journal that once had bragging rights to claim that the shroud was not authentic, Ball wrote: “And of course 'authenticity' is not really a scientific issue at all here: even if there were compelling evidence that the shroud was made in first-century Palestine, that would not even come close to establishing that the cloth bears the imprint of Christ.”
  22. Ball, who was familiar with the evidence, had confirmed what all shroud researchers had been saying for years: the images were not painted. Moreover, a 2003 article in the peer-reviewed scientific journal Melanoidins by Rogers and Anna Arnoldi, a chemistry professor at the University of Milan, demonstrated that the images were in fact a chemical caramel-like darkening of an otherwise clear starch and polysaccharide coating on some of the shroud’s fibers. They suggested a natural phenomenon might be the cause. If this could be proven, the images could be explained in non-miraculous, scientific terms.
  23. If there were not new claims, old ones would be repeated, as in the PBS documentary timed for Easter 2004 viewing. Supposedly, contamination in the form of a microbial "varnish" on the cloth might have skewed the theretofore devastating radiocarbon results. (The tests showed the shroud cloth dated to the 1260-1390 A.D. range, the time when, according to a Bishop's report, a forger confessed he had "cunningly painted" the shroud.) However, skeptics had long ago pointed out that, for the shroud's date to have been altered by thirteen centuries, there would have to be twice as much contamination, by weight, as the cloth itself!