Dating materials and Carbon 14

Society, and especially industry, is an organism in constant advance and evolution. There are objects or techniques that we use today that 50 years ago would have seemed unthinkable to us, and we always have our eyes set on the future and on continuous improvement. Therefore, today we want to talk about a different topic that often goes unnoticed, such as knowing the past through the dating of objects. If you are interested in this topic, keep reading!

What is dating materials?

Dating is the action of assigning or giving a certain time space to an event, or in the case of materials, to an object. Put more simply, it consists in knowing what date the object is, or if some objects are older than others.

Types of materials dating

When we want to know the date of a certain object, there are two possible ways to do it: relative dating and absolute dating.

• Relative dating: this type of dating is not exact and cannot give a specific date, although, nevertheless, it is very useful, since it can determine which objects are older and which are newer.
  The clearest example of this type of dating is in sedimentary deposits. In these deposits, layers of earth are formed, being older the lower they are located. When viewing these layers, it is difficult to determine what date they are, but they serve perfectly to date relatively.

• Absolute dating: this type of dating, unlike absolute dating, provides an exact or quasi-exact date of the antiquity of what is measured. The accuracy and precision of the dating will be determined by the technique used and by the material of the object, but it usually gives the necessary information for the objects that are usually studied.

Materials dating techniques

As we have commented, there are two different types of dating, but we are going to focus on absolute dating, as it is the one that tends to have the greatest interest. Within absolute dating, dating techniques are distinguished depending on the type of material:

• Techniques for organic materials (with carbon): For materials that contain carbon, the most widespread technique and the one that usually gives the best results is that of carbon 14 or radiocarbon dating.
  This technique is based on measuring the number of radioactive isotopes of carbon 14 that are present in an object. These isotopes are constantly generated in the atmosphere (CO2), and plants absorb it through photosynthesis. Then animals, by ingesting plants, absorb these isotopes. Therefore, plants and animals, until they die, incorporate isotopes of carbon 14, but when they die, this process ceases, lowering the concentration of isotopes slowly exponentially. This loss of isotopes is half in 5730 years and reaches amounts impossible to measure after 60,000 years.
  Additionally, there are certain metals that contain carbon in their composition. Such metals, in the form of alloys such as steel, can also be dated using this technique.

• Techniques for ceramic materials: For ceramic materials, as they do not normally contain carbon, carbon 14 cannot be used to date them. In these cases, the thermoluminescence technique is usually used.
• Thermoluminescence as such is the emission of light that occurs in certain crystalline materials when heated. For this phenomenon to occur, the material has previously had to receive radiation for a certain time, to accumulate the necessary energy to later illuminate itself. In turn, the material must also be insulating or semiconductor.
  Materials such as fluorite, apatite, calcite or quartz meet these requirements, so by this method it is possible to know what was the date on which the ceramic materials were baked and produced.
• Techniques for metallic materials: Few techniques are available for these materials and are being actively investigated, as they are based on a certain metal or oxide each.
  To date metallic materials, therefore, it is used to analyze the metals themselves, alloys and impurities presented in the samples, and to compare the percentages of their composition in order to determine the date.

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