Global InformationRehydroxylation dating information
Rehydroxylation [RHX] dating is a developing method for dating fired-clay ceramics.[1] This new concept relies on a key property of ceramic materials, in which they expand and gain mass over time. After a ceramic specimen is removed from the kiln at the time of production, it immediately begins to recombine chemically with moisture from the environment. This reaction reincorporates hydroxyl (OH) groups into the ceramic material, and is described as rehydroxylation (RHX).[2] The phenomenon has been well-documented over the past one hundred years (albeit more focused on limited timescales), and has now been proposed as a means to date fired-clay ceramics. The RHX process produces an increase in specimen weight and this weight increase provides an accurate measure of the extent of rehydroxylation. The dating clock is provided by the experimental finding that the RHX reaction follows a precise kinetic law: the weight gain increases as the fourth root of the time which has elapsed since firing.[3] This power law and the RHX method which follows from it were discovered by scientists from the University of Manchester and the University of Edinburgh.[4]
The concept of RHX dating was first stated in 2003 by Wilson and collaborators[3] who noted that the "results … suggest a new method for archaeological dating of ceramics". The RHX method was then described in detail in 2009[1] for brick and tile materials, and in relation to pottery in 2011.[5] The archaeological pottery first used to test the developing RHX method consisted of three categories of which the dates had already been calculated by other archaeological means. The first was an Anglo-Saxon loom-weight from 560 to 660 AD, a Samian-ware sherd from 45 to 75 AD and three Werra earthenware sherds from 1605 AD.[5] The types of samples used were deemed important for the experiment since they represented "three specific perceived issues associated with applying the RHX method to excavate archaeological pottery."[5] These issues included potsherds found in waterlogged sites, low-firing temperature ceramics, vitrified ceramics and those containing a slip or a glaze.
RHX dating is not yet routinely or commercially available. It is the subject of a number of research and validation studies in several countries.
- ^ a b Wilson, Moira A.; Carter, Margaret A.; Hall, Christopher; Hoff, William D.; Ince, Ceren; Wilson, Moira A.; Savage, Shaun D.; McKay, Bernard; Betts, Ian M. (8 August 2009). "Dating fired-clay ceramics using long-term power law rehydroxylation kinetics". Proceedings of the Royal Society A. 465 (2108): 2407–2415. Bibcode:2009RSPSA.465.2407W. doi:10.1098/rspa.2009.0117.
- ^ Hamilton, Andrea; Hall, Christopher (2012). "A review of rehydroxylation in fired-clay ceramics". Journal of the American Ceramic Society. 95 (9): 2673–2678. doi:10.1111/j.1551-2916.2012.05298.x.
- ^ a b Wilson, Moira A; Hoff, William D; Hall, Christopher; McKay, Bernard; Hiley, Anna (2003). "Kinetics of moisture expansion in fired clay ceramics: a (time)1/4 law". Physical Review Letters. 90 (12): 125503. Bibcode:2003PhRvL..90l5503W. doi:10.1103/PhysRevLett.90.125503. PMID 12688883.
- ^ "Fire and water reveal new archaeological dating method". ScienceDaily. May 25, 2009.
- ^ a b c Wilson, Moira A; Hamilton, Andrea; Ince, Ceren; Carter, Margaret A; Hall, Christopher (2012). "Rehydroxylation (RHX) dating of archaeological pottery". Proceedings of the Royal Society A. 468 (2147): 3476–3493. Bibcode:2012RSPSA.468.3476W. doi:10.1098/rspa.2012.0109.