Does radioactive dating work for gases
After these initial cleaning procedures, each laboratory split the samples for further treatment.
Even for the first investigation, there was a possibility of using radiocarbon dating to determine the age of the linen from which the shroud was woven.
The size of the sample then required, however, was ~500cm, which would clearly have resulted in an unacceptable amount of damage, and it was not until the development in the 1970s of small gas-counters and accelerator-mass-spectrometry techniques (AMS), requiring samples of only a few square centimetres, that radiocarbon dating of the shroud became a real possibility. The shroud was separated from the backing cloth along its bottom left-hand edge and a strip (~10 mm x 70 mm) was cut from just above the place where a sample was previously removed in 1973 for examination.
The Arizona group split each sample into four subsamples.
One pair of subsamples from each textile was treated with dilute HCL, dilute Na OH and again in acid, with rinsing in between (method a).
Following this intercomparison, a meeting was held in Turin in September-October 1986 at which seven radiocarbon laboratories (five AMS and two small gas-counter) recommended a protocol for dating the shroud. The samples were then taken to the adjacent Sala Capitolare where they were wrapped in aluminium foil and subsequently sealed inside numbered stainless-steel containers by the Archbishop of Turin and Dr Tite.
Photography of the shroud by Secondo Pia in 1898 indicated that the image resembled a photographic 'negative' and represents the first modern study.
Two were in the form of whole pieces of cloth (samples 2 and 3) and one was in the form of threads (sample 4). This corresponds to a calendar age, rounded to the nearest 5 years, of 110 cal BC - AD 75 cal at the 68 per cent confidence level (where cal denotes calibrated radiocarbon dates). Threads removed from the cope of St Louis d'Anjou which is held in a chapel in the Basilica of Saint-Maximin, Var, France.On the basis of the stylistic details and the historical evidence the cope could be dated at ~ AD 1290 - 1310 (reign of King Phillipe IV).Because it was not known to what degree dirt, smoke or other contaminants might affect the linen samples, all three laboratories subdivided the samples, and subjected the pieces to several different mechanical and chemical cleaning procedures.But the three laboratories undertook not to compare results until after they had been transmitted to the British Museum.Also, at two laboratories (Oxford and Zurich), after combustion to gas, the samples were recoded so that the staff making the measurements did not know the identity of the samples. On the basis of the Islamic embroidered pattern and Christian ink inscription, this linen could be dated to the eleventh to twelfth centuries AD. Linen from the collection of the Department of Egyptian Antiquities at the British Museum, associated with an early second century AD mummy of Cleopatra from Thebes (EA6707).Zurich precleaned the sample in an ultrasonic bath.