Charcoals as indicators of historical mortar age of medieval Czech castle Pyšolec.

Radiocarbon dating of charcoals and small pieces of wood collected from mortar in the torso of bergfried and buttress of the medieval Pyšolec castle was performed using accelerator mass spectrometers. Altogether, 37 samples were collected, of which 33 samples passed pre-processing criteria and chemical treatment and were dated. Two of them were Palaeolithic charcoals of likely sedimentary origin, one wood sample corresponded to a younger intrusion, six represented 'old wood' likely aged about 200 years when built in, and 24 originated from 'young wood' presumably not older than 50 years at the time of building. This highlights the need to collect large enough sample set when dating architectural remains using charcoals or wood splinters. As a rule of thumb, collecting at least 10 samples is recommended; otherwise, the dating might not be feasible at all or may yield unrealistically old estimates, by as much as 200 years for medieval castles. [ABSTRACT FROM AUTHOR]