that discarding the blind-test method would expose the results – whatever they may be – to suspicion of unreliability. Shredding the samples would not solve the problem, while making it much more difficult and wasteful to clean the samples properly.
Colonetti', Turin, "confirmed that the results of the three laboratories were mutually compatible, and that, on the evidence submitted, none of the mean results was questionable." Although the quality of the radiocarbon testing itself is unquestioned, criticisms have been raised regarding the choice of the sample taken for testing, with suggestions that the sample may represent a medieval repair fragment rather than the image-bearing cloth.The main part of the shroud does not contain these materials." He speculated that these products may have been used by medieval weavers to match the colour of the original weave when performing repairs and backing the shroud for additional protection.Based on this comparison Rogers concluded that the undocumented threads received from Gonella did not match the main body of the shroud, and that in his opinion: "The worst possible sample for carbon dating was taken." As part of the testing process in 1988, Derbyshire laboratory in the UK assisted the Oxford University radiocarbon acceleration unit by identifying foreign material removed from the samples before they were processed.It is hypothesised that the sampled area was a medieval repair which was conducted by "invisible reweaving".Since the C14 dating at least four articles have been published in scholarly sources contending that the samples used for the dating test may not have been representative of the whole shroud.
These included an article by American chemist Raymond Rogers, who conducted chemical analysis for the Shroud of Turin Research Project and who was involved in work with the Shroud since the STURP project began in 1978.