The microscopist Walter McCrone found, based on his examination of samples taken in 1978 from the surface of the shroud using adhesive tape, that the image on the shroud had been painted with a dilute solution of red ochre pigment in a gelatin medium.
the shroud’s linen material was produced between the years 1260 and 1390 (to a 95% confidence level)
Seems legit
That and a shroud that had the impression of a 3D face would look a lot more like this-