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Garza-Valdes and Mattingly kept up their research for several years and then parted ways. "Dr. Garza's science was fine," says Mattingly, "but then he started talking about the Holy Grail, among other things." Garza-Valdes has speculated that some of the bacteria isolated from the shroud could be remnants from the vinegar Jesus was force-fed while on the Cross. "That's absurd," says Mattingly, who nonetheless continues to back the doctor's contention that the bioplastic coating exists on the shroud.
Predictably, the radiocarbon-dating crowd is dubious about Garza-Valdes' claims regarding the bioplastic film. Although he and Mattingly have reported on the topic itself, they have never published a peer-reviewed paper on their shroud work. "The only people who have ever seen these bacteria are Drs. Mattingly and Garza-Valdes," says Arizona's Timothy Jull. "In my opinion, our sample of the shroud was very clean, and there was no evidence of any coating." Even if the hypothetical varnish existed, Jull adds, the amount necessary to throw off the dating by 1,300 years would have been visible to the naked eye. Snipes U.C. Riverside's Taylor: "At the present time, the 'bioplastic theory' has many of the characteristics of cold fusion," the here-one-day-ridiculed-the-next physics fiasco of 1989.
THE IMAGE: DIVINE OR DEVISED? Those who see flaws in the radiocarbon-dating process rest their contentions on a thin precipice of evidence. In contrast, the question of how the image got on the shroud remains a legitimate and tantalizing scientific problem--and just as vulnerable to extrascientific exegesis. The image's most likely origin is an oxidation process akin to the natural aging of linen, but somehow accelerated in the fibers composing the "picture." Some have suggested that an enterprising artist could have created the image of a crucified man by daubing an acidic liquid (everything from sweat to lemon juice to sulfuric acid) on the cloth in the appropriate places and then exposing the material to heat. To attain a three-dimensional look, several investigators have suggested that a wet cloth was put over a bas-relief of a man and then burnished with iron oxides.
Throwing microbes into the mix would actually ease the production of an image. Says microbiologist Mattingly: "Imagine you've just come back from jogging and you're all sweaty, and you gently press a towel against your face. Now instead of throwing it into a corner, you set it carefully aside for several months. When you wiped your face, you transferred to the towel sweat, detritus and microbes that will grow and eventually form the image of a face."