Assumptions to carbon 14 dating
Other processes may affect the local concentrations of carbon-14.These effects are corrected for by comparing samples from different locations. Int Cal09 and Marine09 radiocarbon age calibration curves, 0-50,000 years cal BP.  This was the scroll “Testament of Qahat,” for which the radiocarbon date was about two centuries older than the date based on paleography. Evolutionists have long used the carbon-14, or radiocarbon, dating technique as a “hammer” to bludgeon Bible-believing Christians.While the small variations in isotope decay that have been reported may not invalidate all isotopic dating, they raise questions about the assumption of completely uniform decay rates.A second assumption is that the sample being dated has not experienced any loss or contamination of C over its history.
C dating consists of measuring the amounts of carbon-14 and carbon-12, and sometimes C-13, in a sample.
Violations of this assumption can frequently be identified.
Three additional assumptions are necessary in radiocarbon dating in order to estimate the initial concentration of C could be caused by changes in the intensity of the cosmic radiation or in the strength of the earth’s magnetic field.
The reasonableness of this assumption probably depends on the environment around the sample.
A sample that is sealed from the surrounding environment is more likely to avoid contamination or loss than one in an open environment where materials may be carried into or out of the sample by water or simple diffusion.
Why do ancient samples of coal, diamonds and other carbon-containing materials consistently contain  The first such curve was published by: Arnold, JR and WF Libby. High-precision (super 14C measurement of Irish oaks to show the natural 14C variations from AD 1840 to 5210 BC.