Originally posted by RJHinds You did not read. This was not the normal C-14 testing, but FT-IR testing. That is Fourier transform infrared (FTIR) spectroscopy which can be used to date things.
I did my graduate work in atomic spectroscopy and I believe that FT-IR can only be used for dating in an indirect way. For example if it is known that a certain painting pigment was only in use during a certain time period, FT-IR can confirm whether the pigment is present in a painting and if so, that can date the painting to the time period. I am not aware of how FT-IR was used in looking at the shroud.
Originally posted by JS357 I did my graduate work in atomic spectroscopy and I believe that FT-IR can only be used for dating in an indirect way. For example if it is known that a certain painting pigment was only in use during a certain time period, FT-IR can confirm whether the pigment is present in a painting and if so, that can date the painting to the time period. I am not aware of how FT-IR was used in looking at the shroud.
It has advanced since your graduate work. It now can be used to date both organic and inorganic particles as I understand it. FT-IR is the way these last dates were obtained because no part of the shroud has to be destroyed that way. The scientist have determined that the shroud is not a painting, so obviously they would not use Ft-IR if it could only date paintings.
I can't say this dating method is accurate since I am not a scientist. However, it has been stated that it is a very accurate dating method and there is no examples of wildly inaccurate dates given like there is for C-14 dating.