Not too surprising. I can reproduce stigmata on my hands with just a rusty thumbtack.
A professor of organic chemistry at the University of Pavia, Garlaschelli made available to Reuters the paper he will deliver and the accompanying comparative photographs.
They placed a linen sheet flat over a volunteer and then rubbed it with a pigment containing traces of acid. A mask was used for the face.
The pigment was then artificially aged by heating the cloth in an oven and washing it, a process which removed it from the surface but left a fuzzy, half-tone image similar to that on the Shroud. He believes the pigment on the original Shroud faded naturally over the centuries.