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historical problem for the shadow theory
. . . in referece to the wikipedia text,
solar masking, or "shadow theory"
the type of glass needed for Wilson's proposed shadow shroud process did not exist in 1357, the latest possible date for the Shroud of Turin if it was a fake-relic.
It wasn't until the nineteenth century that glass suitable for Wilson's shadow shroud could be produced. The first flat plate glass wasn't produced until 1688. Before then, plate glass was blown plate, which was rare, very limited in size and very distorted. Glass, very rare in 1356, was poor quality with many imperfections. According to the PPG Industries website:
Flat glass for windows was still rare during much of the 17th and 18th centuries. Small panes were made by blowing a large glob of glass, removing it from the blowing iron and then rotating the glass quickly so it would spread and flatten. Such glass had a dimple in its center, many air bubbles and a pattern of concentric circles, but it was transparent and effective in keeping out the weather. At the end of the 17th century, the French learned how to grind and polish cast glass to produce plate glass, but only the rich could afford it.
Great strides were made in the manufacture of flat glass during the 19th century. Compressed air technology led to flatter, better glass panes. Controlled amounts of air were used to blow a large glass cylinder, which was slit lengthwise, reheated and allowed to flatten under its own weight. Large, relatively inexpensive lites of glass were produced in this manner.
Return to summary of why the shadow theory fails. See:
solar masking, or "shadow theory"
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