Material intrusion is well known in the application of carbon 14 dating.
A classic example is to be found in the dating of peat bogs.
Chemical tests show that dye is yellow alizarin from madder root complexed with alum, a common mordant. Cotton, alizarin and gum are only found in the C14 sample area of the shroud.
The roots of these plants, sometimes having decomposed, are nearly indistinguishable from the older peat.
For material that is only a few thousand years old, carbon 14 dating is very accurate and very reliable.
Because of the carbon 14 dating, the Shroud of Turin, a religious object important to Christians of many traditions (Catholic, Orthodox, Anglican, Protestant and Evangelical; conservative and liberal alike) has been cast into the spotlight of secular science.
Students will ask why a single sample from a suspect corner was used.
They will wonder why protestations from experts in the Shroud’s chemistry were ignored.
John Dominic Crossan, the famed Jesus Seminar scholar, proposed that someone in medieval times was crucified by a crafter of fake relics in order to produce the Shroud.