Surface Crystallisation on Beeswax Seals
| Main Authors: | , |
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| Format: | Article |
| Language: | English Slovak |
| ISSN: | ISSN 0034-5806 |
| Online Access: | http://www.viks.sk/chk/res_4_02_256_269.doc |
| Abstract: | CONCLUSIONS. The surface crystallisation of beeswax was studied with respect to historic seals. Alkenes with 31, 32, 33 and 35 carbon atoms were identified in crystalline samples together with other components of beeswax, e.g., alkanes and monoesters. Alkenes were present in the amount of 42.3-91.1%, and this variable amount most probably results from the character of the crystalline layer. As the same alkenes are also present in the beeswax itself, a crystallization of the beeswax fraction of alkenes was observed on the surface of seals when cooled. From tests with model seal castings a significant dependence of this on the temperature of the environment was found, with a critical temperature between 12°-16°C. A moderate crystallisation was observed in the temperature range of 16°-27°C whereas at 12°C and below an intense and swift crystal formation was observed on the beeswax surface. An attempt was made to explain this phenomenon using the information about the structure of beeswax and comparing beeswax with other systems composed of a polymer and a plasticizer. Alkenes were suggested to work as plasticizers in the complex beeswax mixture, which are in the liquid state at room temperature. However, a melting point of 34°-35°C was measured after their isolation. The difference between the melting and crystallisation temperature was explained by a supercooled liquid state of alkenes. Under further cooling, a change of this supercooled liquid into a crystalline solid state takes place. Although this phenomenon is supposed to be reversible to a certain extent, a temperature of 16°C is advisable as a minimum for storing seals, in order to avoid large surface crystallisation and to keep the original appearance of beeswax seals. SUMMARIES. Surface crystallisation on beeswax seals Surface crystallisation occurring on seals made of pure beeswax was investigated. The composition of crystals was determined using gas chromatography (GC), gas chromatography/mass spectrometry (GC/MS) and direct temperature resolved mass spectrometry (DTMS). Alkenes with 31, 32, 33 and 35 carbon atoms and one double bond were found to be the main components. As the same compounds are also present in beeswax itself, the crystallization of a beeswax fraction of alkenes was observed. Model seal castings were used for testing different factors, which may influence crystallisation. A strong dependence of crystallisation on temperature was found and a hypothesis was proposed explaining these observations. |
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| ISSN: | ISSN 0034-5806 |
