Carbon-dating tests were conducted on the cloth in 1988 and suggested it was from between 1260 and 1390, other scientists have since claimed that contamination over the ages, from water damage and fire, were not taken sufficiently into account and could have distorted the results.
As a result of controversy and the fact that dating techniques have improved significantly since the 1988 tests were done, there have been numerous calls for further testing but the Vatican has always refused.
The carbon dating tests were skewed because of carbon contamination from a fire in the Middle Ages that subjected the shroud to smoke damage at that time.
Also, I saw a study once about the shroud. In this study, a botanist found spores from specific plants on the shroud.
The plants which produced the spores were found only in Bethlehem, Nazareth, and other cities and towns in the Biblical Holy Land.....places were Jesus and his disciples were located and the area where it is believed Jesus was crucified.
http://www.shroudstory.com/faq/
It’s not a fake. But then again, a man walked the earth who raised people from the dead, cured the blind, etc., and still people did not believe.
It was later determined that the piece of cloth that was carbon tested was actually from a piece that was added in the 1200s to replace the burned edges.
Plus, a plant expert found pollen that was over around 2000 years old and is only found in the Middle East.
The Shroud is now immersed in a bath of some chemical to protect it from decaying more. This chemical bath evidently prohibits any accurate carbon testing now. It really is not important. The Shroud has been proven authentic...the question is not is it real or fake, but is it Jesus or not. There is not way it was created in the middle ages as the technology for knowing the different light wave frequencies that have been used to prove it’s authenticity were known back then...the image is also contains 3 dimensional information...that precludes it from being any kind of painting, dyeing, etc.