I believe that there are several things wrong with these hypotheses.
Even assuming that the coating formed all at once in the 20th Century during a highfallout time, when bomb-produced 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.
For example, they detected traces of furfural from the anomalous pentosan gum layer in the radiocarbon-sample area. Adler spent many hours looking at samples from the Shroud under microscopes and running microchemical spot tests.
The scientific study of the Turin Shroud is like a microcosm of the scientific search for God. It is simply not known how the ghostly image of a serene, bearded man was made. The image remains inexplicable, baffling, downright weird.
It does more to inflame any debate than settle it . Ball’s assertion that it is not known how the image was made is correct. So far, even with the best of modern technology no one has been able to replicate it. Its mysterious qualities are among the most entertaining and intriguing aspects of the shroud.
The chemical components of biopolymers can be detected with great sensitivity. Rogers took authentic Shroud fibers, which she laboriously extracted from the STURP sampling tapes by washing them free of adhesive with xylene (not a solvent for any "bioplastic polymers"), to Metuchen, NJ, for laser-microprobe Raman analysis.
The analysis is extremely sensitive, but nothing was observed that would indicate a "bioplastic polymer." She also took fibers to the NSF Mass Spectrometry Center of Excellence at the University of Nebraska.