bioplastic

Garza-Valdes and the Mayan Jade Artifact

In 1983, Leoncio Garza-Valdes, a medical doctor in San Antonio, Texas, and an amateur archaeologist, was examining a Mayan jade artifact that was assumed to be modern forgery. He was puzzled by lacquer-like coating on the object that he speculated might have been produced by bacteria. Garza-Valdes took the artifact to the radiocarbon dating lab at the University of Arizona. Scientists there were able to scrape off enough of the coating, as well as some bloodstains on the object, to give a date of about A.D. 400. The carving style suggested that the age should have been about 200 B.C.. However, if the bioplastic-polymer, for that is what it seemed to be, had been forming over the centuries, it would be a mixture of older and newer material. So perhaps the object really was 600 years older.

Following the carbon dating of the shroud, it occurred to Garza-Valdes that perhaps the fibers of the shroud were also coated with a bioplastic coating. And perhaps this also affected the carbon dating of mummy 1770. If ancient linen was subject to such a coating, then all bets were off on the carbon dating of the shroud until it was examined.

Garza-Valdes managed to inspect *** in Turin. Stephen Mattingly ****

The Ibis Mummy

Things were heating up. Harry Gove, a prominent radiocarbon dating expert from the University of Rochester in New York, who had wanted to be part of the carbon dating of the shroud and not been selected, was now involved. Ann Rosalie David, who had been part of the team that had studied mummy 1770, was involved as well. They met at the University of Texas Health Science Center in Austin. David brought a mummy of an ibis, a bird that the ancient Egyptians considered sacred. They had been careful to select one that seemed unlikely to have been rewrapped. They extracted samples of both tissue and bone from the bird as well as linen fabric from its wrappings. These they took to the National Science Foundation Accelerator Mass Spectrometry Facility at the University of Arizona, one of the same labs involved with the shroud’s dating.

The linen appeared to be newer than the bird it wrapped. And unless the bird was rewrapped—which seemed implausible to the four researchers—then appearances contradicted reality. They clearly saw something that seemed to be a bioplastic coating. But they entertained another possibility as well: the bird’s diet.

Conflicting Results

They noted that  radiocarbon measurements on charcoal and snail shells from the Graeco-Roman period in Egypt gave very conflicting results. The snail problem has surfaced. Not only might snails be a problem, but so to might anything that ate snails from water rich in depleted carbon like those found in artesian spring in Nevada.

But they seemed to prefer “bacterial infestation.” And the concluding paragraph of their paper makes this clear, but with a significant amount of caution.

Meanwhile, although the results of the present measurements include the possibility that the bioplastic coating observed on the cloth fibers of the wrappings of the ibis cause it to yield a radiocarbon age several hundred years younger that it true age, they are far from definitive. It would be premature to draw any conclusions about the true age of the Turin Shroud from these measurements. (49)

 U.S. News & World Report

It didn’t play out that way. If you were looking for a way to dispute that carbon dating of the shroud, you had it. Though it may have been premature of draw any conclusions about the true age of the shroud you could say, quite validly, that the sheen was off the carbon dating of the shroud. Unless Gove, et. al. were proven wrong, there was reason for reasonable doubt. 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.”

Garza-Valdes and the Scanning Electron Microscope

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 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.

No Bioplastic

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.

Lloyd A. Currie

As the Associated Press, the BBC and The New York Times reported on Rogers’ paper, some people wondered, just as Ball had, if it was possible that threads “were woven into the old cloth so cunningly that the textile experts who selected the area for analysis failed to notice the substitution.”  Others wondered if there was perhaps more to the story. Was this the whole story? How could such a mistake in radiocarbon dating happen? Was there something to learn from this?

About a year before Rogers’ paper was published, in early 2004, the Journal of Research of the National Institute of Standards and Technology (U.S. Department of Commerce, NIST, U.S. Government Printing Office) published an important paper by Lloyd A. Currie. Currie, a highly regarded specialist in the field of radiocarbon dating and an NIST Fellow Emeritus, wrote a seminal retrospective on carbon 14 dating. Because the Shroud of Turin was such a famous test, Currie devoted much of his paper to it.

Like Rogers, Currie dismissed any argument that radiocarbon labs had done anything wrong in dating the Shroud of Turin. Currie also rejected, as Rogers also had done, the theories of scorching effects or contamination caused by a bioplastic polymer. Significantly, Currie acknowledged that disguised mending was a viable explanation. He cited the work of Rogers and Arnoldi. He found it credible.