Radiocarbon dating the turin shroud
Levels of vanillin in material such as linen fall over time.
'Older date' "The fact that vanillin cannot be detected in the lignin on shroud fibres, Dead Sea scrolls linen and other very old linens indicates that the shroud is quite old," Mr Rogers writes.
"This stuff was manipulated - it was coloured on purpose." In the study, he analysed and compared the sample used in the 1988 tests with other samples from the famous cloth.
In addition to the discovery of dye, microchemical tests - which use tiny quantities of materials - provided a way to date the shroud.
Raymond Rogers says his research and chemical tests show the material used in the 1988 radiocarbon analysis was cut from a medieval patch woven into the shroud to repair fire damage.
It was this material that was responsible for an invalid date being assigned to the original shroud cloth, he argues.
The author dismisses 1988 carbon-14 dating tests which concluded that the linen sheet was a medieval fake.
The shroud, which bears the faint image of a blood-covered man, is believed by some to be Christ's burial cloth.
Frank Wognum, Duffort, France I think that regardless of whether it is or is not Christ's burial cloth, testing should still be allowed to take place.
It is said to have been restored by nuns who patched the holes and stitched the shroud to a reinforcing material known as the Holland cloth.
"[The radiocarbon sample] has obvious painting medium, a dye and a mordant that doesn't show anywhere else," Mr Rogers explained.
"The radiocarbon sample has completely different chemical properties than the main part of the shroud relic," said Mr Rogers, who is a retired chemist from Los Alamos National Laboratory in New Mexico, US.
Fire damage He says he was originally dubious of untested claims that the 1988 sample was taken from a re-weave.