Wood, ivory, bone, textiles may be dated and analyzed by different methods:
- Radiocarbon - C14
- Modernity marker
- X-Ray radiography
Radiocarbon - C14
Radiocarbon dating determines the time elapsed since the death of the body (the felling of the tree or the death of the elephant for example). A sample of 30 mg is sufficient.
Radiocarbon dating is based on the measurement of the decay of the isotope carbon 14 (C14) contained in all organic materials.
A living organism assimilates carbon without distinction. The proportion of C14 remains stable throughout life.
When the body dies, the exchanges with the outside stop. The amount of C14 then decreases over time according to a known law: its concentration is halved every 5730 years.
By measuring the ratio C14 / C total, define a time interval.
The accuracy of dating depends on the length of the material. It can vary from 30 years for materials older than 300 years, 200 years younger (between the 18th century and 1954), because of the necessary calibration ages C14.
Atmospheric nuclear testing in the middle of the 20th century have greatly increased the concentration of carbon-14 in the air. That is why animals and vegetals who lived after 1954 contain abnormally high levels of C14.
These abnormally high levels of C14 define a modernity marker.
We can easily distinguish an authentic object of the late 19th - early 20th centuries and a copy of the late 20th century.
In addition, the measurements obtained for objects post-1954 allow very precise dating (interval less than 5 years).
The observation by X-ray radiography is used to evaluate the homogeneity of the piece and identify restoration areas, areas of connection between ancient and modern materials.
Dendrochronology can date the wooden objects to a few years, counting and analyzing the morphology of the growth rings (or rings) of trees.
Unfortunately, this technique is limited to timber growing under midlatitudes. That is why it is not applicable to African objects in particular. In addition, it requires the observation of an area with dozens of rings (several cm).