Radiocarbon dating explained endpoint not updating 2016
Even a hypothetical sample containing absolutely no radiocarbon will register counts in a radiocarbon counter because of background signals within the counter.
First, any instrument which is built to measure radiocarbon has a limit beyond which it cannot separate the signal due to radiocarbon in the sample from the signal due to background processes within the measuring apparatus.
Link: Radiocarbon Dating of the Turin Shroud: New Evidence from Raw Data © Oxford University 2019 Abstract: In 1988, three laboratories performed a radiocarbon analysis of the Turin Shroud.
The results, which were centralized by the British Museum and published in Nature in 1989, provided ‘conclusive evidence’ of the medieval origin of the artefact.
Some organic materials do give radiocarbon ages in excess of 50,000 "radiocarbon years." However, it is important to distinguish between "radiocarbon years" and calendar years.
These two measures of time will only be the same if all of the assumptions which go into the conventional radiocarbon dating technique are valid.
Radiocarbon is not suitable for this purpose because it is only applicable: a) on a time scale of thousands of years and b) to remains of once-living organisms (with minor exceptions, from which rocks are excluded).