In addition, samples need to be thoroughly cleaned to remove carbon contamination from glues and soil before dating.
Moving away from techniques, the most exciting thing about radiocarbon is what it reveals about our past and the world we live in.
Radiocarbon dating was the first method that allowed archaeologists to place what they found in chronological order without the need for written records or coins.
If 1% of the carbon in a 50,000 year old sample is from a modern contaminant, the sample will be dated to around 40,000 years.
Because of this, radiocarbon chemists are continually developing new methods to more effectively clean materials.
Rachel Wood does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
Australian National University provides funding as a member of The Conversation AU.
The second difficulty arises from the extremely low abundance of C, making it incredibly difficult to measure and extremely sensitive to contamination.
In the early years of radiocarbon dating a product’s decay was measured, but this required huge samples (e.g. Many labs now use an Accelerator Mass Spectrometer (AMS), a machine that can detect and measure the presence of different isotopes, to count the individual C atoms in a sample.
Radiocarbon dates are presented in two ways because of this complication.
The uncalibrated date is given with the unit BP (radiocarbon years before 1950).
The calibrated date is also presented, either in BC or AD or with the unit cal BP (calibrated before present - before 1950).