Idea tha Bioplastic Coating Contaminated Carbon 14 Sample - Not Widely Accepted
The hypothesis that a bioplastic coating on the Shrouds fibers skewed the carbon 14 dating has repeatedly been demonstrated to be invalid.
Leoncio Garza-Valdes and Stephen Mattingly of the University of Texas claimed finding an organic bioplastic contamination on the Shroud that would not have been removed with the cleaning process that the carbon 14 dating labs used in 1988.
The bioplastic idea gained acceptance among many Shroud researchers when Harry E. Gove, a nuclear physicist at the University of Rochester who designed the carbon-dating methods used on the Shroud, gave tentative support to Garza-Valdes and Mattingly. Jeffery L. Sheler, writing in the July 24, 2000, issue of U.S. News & World Report, quotes Gove as saying, "There is a bioplastic coating on some threads, maybe most." Gove goes on to say that if there is a sufficient quantity of bioplastic it "would make the fabric sample seem younger than it should be."
But the bioplastic idea came up short. Garza-Valdes had said: "With a scanning electron microscope, I found the fibers were completely covered by the bioplastic coating (polyhydroxyalkanoate) and by many colonies of fungi which usually thrive on this polymer..."
But other scientists find this statement flawed and this probably explains why the bioplastic idea was never published in a peer reviewed journal. For one thing, there is no way to determine the definitive composition of an organic material by scanning electron microscope. Garza-Valdes provided photomicrograph showing a "filamentous cell" that turned out to be an ultimate cell from the flax structure. Furthermore, it is well known that such polymers (they do exist on some ancient objects) obtain their carbon material from the host (fibers in this case) and not from the atmosphere, hence they do not significantly alter the C14 dating. Even if they could alter the date, the amount of material needed would need to be significant. On this point, Gove took exception with the bioplastic theory and agreed.
Ray Rogers explained: "Even assuming that the coating formed all at once in the 20th Century during a high fallout time, when bomb-produced 14C was high, an observable error in the age determination would require the addition of a significant amount of material to the surface of the Shroud."
Because significant material could be easily detected, fibers from the Shroud were examined at the National Science Foundation Mass Spectrometry Center of Excellence at the University of Nebraska. Pyrolysis-mass-spectrometry examination failed to detect any form of bioplastic polymer on fibers from either non-image or image areas of the Shroud. Additionally, laser-microprobe Raman analysis at Instruments SA, Inc. in Metachin, NJ, also failed to detect any bioplastic polymer.
