Rehydroxylation [RHX] dating is a developing method for dating fired-clay ceramics. 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. 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 dating increases as the fourth root of the time which has elapsed since firing. The concept of RHX dating was first stated pottery by Wilson and collaborators [ 3 ] who noted that read article "results … suggest a new method for archaeological dating of ceramics".

The RHX method was then described in detail in [ 1 ] for brick and tile materials, and in relation to pottery in RHX dating is not yet routinely or commercially available. It is the subject of a number of research and validation studies in several countries. The concept of clay ceramic expansion, post-firing, has been the object of discussion for a long time, first noted by Schurecht in [ 6 ] to explain crazing in ceramic glazes, and confirmed in by McBurney that this and the expansion of ceramic bodies is due to the intake of moisture from the environment.

Init was proposed that moisture expansion could extend over much longer periods of time, contrasting with the previous research over dating limited time scales. For example, if the weight of a fired-clay ceramic increases as a result of RHX by 0. The reason pottery this quartic root dependence is uncertain, however further research is pottery conducted to explain why, including NMR and IR spectroscopy.

First a small sample of the material is obtained. To do so, the ceramic artefact is wet cut using a water-cooled saw to avoid producing heat and consequently causing some dehydroxylation. After the preparation of the sample is complete, it is transferred to a microbalance chamber and exposed to water vapour at a controlled temperature identical to the first Pottery and relative humidity to determine the kinetics of the mass gain through recombination with water. Once this think, westchester hookups consider has been carried out for the desired length of time on average one to two daysthe mass data are recorded.

Once the RHX rate is determined, it is possible to calculate exactly how long ago it was removed from the pottery, [ 4 ] and therefore assign a date to the material.

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To determine the date of the material, the rate of the pottery gain needs to be calculated using the following equation:. The older the sample, the greater the mass gained from combining chemically with water, since the initial mass of the sample is equal to the sum of that of the original fired material pottery the water combined with it over its lifetime. To ensure the date is accurate, either multiple samples from the same artefact can be taken and analysed, or the sample can be dated again using an alternative means and the results compared.

When developing the method, it was important to understand whether variations in humidity affect the RHX mass gain rate of the ceramic material. Little research had not yet examined this in-depth. Therefore, a study was carried out dating samples from the XIX th and XX th centuries, [ 11 ] in which they dehydrated the samples to remove any physically and chemically bonded water and placed them in conditions which were varied between dry and humid extremes.

The conclusion was that variations in humidity do not affect the kinetics of RHX since it only affects the physically bonded water content, rather than the chemically bonded hydroxyl ions. Neither systematic nor transient changes in humidity have an effect on long-term rehydroxylation kinetics.

However, they do affect instantaneous gravimetric measurements or introduce systematic error, for example through capillary condensation. Changes in temperature can strongly affect the rate of RHX and this may impact the calculated age of the ceramic. To illustrate this, the hypothetical example of a year-old sample is used. Therefore, after the first years, the rate of RHX increases. The mass of the material also begins to increase at a faster rate than previously. The method of calculation is based on temperature data for the location, with adjustments for burial depth and long-term temperature variation from historical records, [ 12 ] such as seasonal and climatic changes.

This information is used to estimate an effective lifetime temperature or ELT which is then used in the dating calculation. Closer analysis revealed that the exterior of the brick contained vitrified elements, indicating that it had been exposed to extreme heat since the original time of firing.

This was dating to the brick having been dehydroxylated by the intense heat of incendiary bombing and fires during World War II. The main application of the RHX technique is to date archaeological ceramics.

Yet most archaeological material contains components which causes either addition mass gain or additional mass loss during the RHX measurement process.

Removing the contaminants without affecting the RHX technique is currently being researched. The method deemed the most effective out of the others tested consisted of an acid-base treatment, using hydrochloric acid HCl to clean the samples, followed by a solution of hydrogen peroxide H 2 O 2 to oxidise them.

Though pottery has only been established on bricks and tiles of up to 2, years of age, research is continuing to determine whether RHX can be accurately used on any fired-clay material, for example earthenware of up to 10, years of age.

Extracting Pottery Residue for Radiocarbon Dating

The potential capacity for further adsorption of water could extend to 10, years, since the kinetic power law on which the method relies remains true for large time scales. The original work of Wilson and co-workers was undertaken on construction materials, bricks and tiles. These studies have encountered issues with components within the ceramics, including the mineralogy or the temper added to the clay, causing either addition mass gain or additional mass loss during the RHX measurement process.

The quality of data generated by the Manchester and Edinburgh groups has been due to analysing fired-clay materials which do not contain these components. Efforts to successfully replicate the original work and overcome the challenges presented by archaeological ceramics are underway in several academic institutions worldwide.

One example of this research is a study from that was conducted on sherds of XIX th century Davenport ceramics excavated in UtahUnited States of America to assess the validity of the original method, specifically the rate equation.

Therefore, in order to dehydrate the sample effectively, a suitable temperature needs to be chosen to avoid compromising the integrity of the sample components. It was also concluded that more research needed to be carried out to further examine the effects of mineralogy on RHX dating. A more recent analysis from on potsherds from southern ApuliaItaly proved the potential for the RHX method to become a reliable "alternative or ancillary" [ 21 ] means of dating ceramics. The samples used were fragments of Byzantine pottery which had been dated previously by association with other artefacts using radiocarbon analysis.

Meanwhile, it was noted that since RHX dating has not been tested sufficiently, it cannot yet replace more conventional ways of dating pottery, such as pottery which has extensive proof of its accuracy. The ages calculated for the Byzantine sherds through RHX dating were concurrent with the known ones. The study also emphasised the possible value of this method in refining chronological pottery seriation in cases where the pottery style remains similar over extended periods of pottery in a specific region, such as the Byzantine vessels examined.

Overall, the RHX dating technique shows great potential within the field of Archaeology and research dating to allow for its use in more general studies. Contents move to sidebar hide. Article Talk. Read Edit Dating history. Tools Tools. Download as PDF Printable version. In other projects. Wikidata item. Method for dating fired-clay ceramics.

Power-law kinetics [ edit ]. Dating methodology [ edit ]. Technical issues [ edit ]. Check this out and application of the method [ edit ]. References [ edit ]. Proceedings of the Royal Society A. Journal of the American Ceramic Society. Physical Review Dating. Bibcode : PhRvL.

PMID May 25, May ISSN Proceedings - American Society for Testing and Materials. Journal of Archaeological Science. Bibcode : JArSc. Hall, C. Bibcode : JArSc. E Izvestiya, Physics of the Solid Earth.

Archaeological dating by re-firing ancient pots

Bibcode : IzPSE. Physics World. Applied Clay Science. Bibcode : ApCS Quaternary This web page. Bibcode : QuGeo.

Power-law kinetics

A southern Italian case study". European Journal of Postclassical Archaeologies. Categories : History of ceramics Ceramic engineering Dating methodologies in archaeology Ceramic materials Archaeology. Hidden categories: CS1 maint: multiple names: authors list Articles dating short description Short dating matches Wikidata.