Actually, the test was accurate and returned an accurate average dating for the sample that was tested: original shroud combined with mid 16th Century patch material. The original protocol called for 8 samples to be taken from eight separate areas of the shroud. Unfortunately, the protocol was literally tossed out at the last minute and only one master sample was cut from the Shroud... from the area all advisors had recommended be avoided. From that 1 cm x 5cm master sample, five sub-samples were cut. Two ~ 1cm x 1cm sub-samples cut ends of the master were given to the Arizona C-14 Lab, the next two on either end were given to Zurich and London, and the center sub-sample was retained for future reference... which later proved to be invaluable in discrediting the C-14 ages reported from the other four samples!
In fact, the range of the average datings of the four tested sub-sample showed up a major discrepency that should have raised red flags for the C14 physicists and chemists who did the test. NONE of the four tested samples dates and ranges of confidence (from 20 to 29 years plus of minus on either side of each sub-sample's average test dates) overlapped any of the other sample's dates! This should not be.
But, because the false average age fell so nicely into what they wanted it to be, none of the scientists bothered to ask themselves why there was a discrepency in something that should report the same age, regardless of the lab performing the tests.
In fact the range of reported ages for the unitary master sample, only 1 cm by 5 cm or so, spanned over an extraordinary possible 150 years... but each individual sample had only a 25 year +/- degree of confidence... which should have made the scientists sit up and take notice of something very strange.
They should have asked themselves WHY the sub-sample cut from end of the master sample closest to the main body of the Shroud would test 130 years YOUNGER than the sub-sample cut from the part of the master sample closest to the edge of the cloth. When they saw that the two in-between samples were progressively younger the farther away from the edge their position, the scientists should have again asked why and started looking at the physical make-up of their master sample (which was required by the established original test protocols but was totally ignored by those actually doing the testing!).
They would have seen what the late chemist Ray Rodgers saw and proved when he analyzed the remaining sub-sample: The sample was not homogenous! They would have found that left side of the sample was not the same as the right side and that there was a diagonal line/area running length-wise down the middle of the master sample of combined "newer" material on the left side interwoven into the older, "original" Shroud material on the right side... and that the proportions of each (running between ~65% new to ~50% new (depending on the sub-sample's distance from the edge) was directly proportional to the age discrepencies (the more newer material the younger the cloth's age was reported to be).
One of the Arizona lab's C-14 specialists, when asked "Assuming that the newer material was harvested in 1550AD, how old would the original material have to be for that much "newer" material to skew the dates to ~1260AD to ~1390AD?" replied, after doing some quick math on a calculator, "It would have to be 1st Century plus or minus 100 years."
In Shroud research and scholarship circles, a unpublished report has been circulating for many years about an unauthorized C-14 test of one of the threads taken from the Shroud in the 1978 test. That unauthorized test also returned an origin date of about 50 AD (+/- 75 years).
Now the serious part: does there exist a map of what-was-taken-from-where-when?