Sample Selection

Radiocarbon dating is a powerful technique but selection of the best samples for dating is essential to successful application. In all cases it is necessary to think about the relationship between the sample and the events of interest.

Despite its strengths, the resolution of radicoarbon dating is limited and so it is well worth checking the resolution of the method at different time periods by simulations using OxCal.

Single entities (samples which originate from a single organism) are often the best type of sample for dating and in these cases identification to species or genus level is very useful. We can suggest people who may be able to help with this type of analysis.

Your Samples

Sample size is a constraint in selection of samples for dating. The following table shows some common material types and the typical ideal, and minimum sample sizes for analysis.

Material	Ideal Weight	Minimum Weight	Comments
Bone, antler or ivory	600mg	100mg	Depending on collagen preservation and method used
Charcoal or charred seeds	100mg	5mg
Insect remains	50mg	5mg	Depending on the methods used
Plant remains, cotton, linen or paper	100mg	20mg
Shells or other carbonates	50mg	15mg
Sediments	50mg	15mg	Depends strongly on carbon content and fraction being dated
Silk, wool or hair	120mg	30mg
Wood	100mg	20mg

Sampling

The taking of samples is part of the dating service at ORAU and for many types of sample we would recommend either submitting objects to be sampled for return or visiting the lab so that sampling can take place on-site. In some cases we can sample on location.

In the case of samples that require specialist skills that we do not have in-house, such as the picking of forams, we can often put users in touch with those who have the relevant expertise.

Restrictions

We reserve the right to refuse samples for dating. Reasons for this include:

where the dating of the material might adversely affect our existing commitments (e.g. material enriched in radiocarbon or very large numbers of samples at short notice)
where the date may inadvertently encourage the trade in antiquities looted from archaeological sites (see our Policy on the dating of Antiquities)
where the date is intended to be used for advertising the sale of antiquities (see our Policy on the dating of Antiquities).