The most popular and often used method for calibration is by dendrochronology.
The science of dendrochronology is based on the phenomenon that trees usually grow by the addition of rings, hence the name tree-ring dating.
Dendrochronological findings played an important role in the early days of radiocarbon dating.
Dendrochronological dating and wiggle-matching of radiocarbon dates allowed us to determine the narrow chronological intervals of icon creation.
Although five icons were dendro-dated successfully, one failed to be reliably cross-dated with the existing master tree-ring chronologies and it was dated by radiocarbon wiggle-matching.
It should be noted that a BP notation is also used in other dating techniques but is defined differently, as in the case of thermoluminescence dating wherein BP is defined as AD 1980.
It is also worth noting that the half-life used in carbon dating calculations is 5568 years, the value worked out by chemist Willard Libby, and not the more accurate value of 5730 years, which is known as the Cambridge half-life.
Carbon consists of 99% carbon-12, 1% carbon-13, and about one part per million carbon-14.
Results of carbon-14 dating are reported in radiocarbon years, and calibration is needed to convert radiocarbon years into calendar years.Calibration of radiocarbon results is needed to account for changes in the atmospheric concentration of carbon-14 over time.These changes were brought about by several factors including, but not limited to, fluctuations in the earth’s geomagnetic moment, fossil fuel burning, and nuclear testing.Age ranges are calculated either by the intercept method or the probability method, both of which need a calibration curve.The first calibration curve for radiocarbon dating was based on a continuous tree-ring sequence stretching back to 8,000 years. The results of dendrochronological and radiocarbon dating by means of accelerator mass spectrometry (AMS) of six medieval icons, originating from northern European Russia and painted on wooden panels made from Scots pine, dated to the 15th to 17th centuries are presented.