Waxing

Wax deposition is one of the chronic problems in the petroleum industry.
The various crude oils present in the world contain wax contents of up to
32.5%. Paraffinwaxes consist of straight chain saturated hydrocarbons with carbons atoms ranging fromC18 to C36. Paraffin wax consists mostly with normal paraffin content (80–90%), while, the rest consists of branched paraffins (isoparaffins) and cycloparaffins. The sources of higher molecular weight waxes in oils have not yet been proven and are under exploration. Waxes may precipitate as the temperature decreases and a solid phase may arise due to their low solubility. For instance, paraffinic waxes can precipitate out when temperature decreases during oil production, transportation through pipelines, and oil storage. The process of solvent dewaxing is used to remove wax from either distillate or residual feedstocks at any stage in the refining process. The solvents
used, methyl-ethyl ketone and toluene, can then be separated from dewaxed oil filtrate stream by membrane process and recycled back to be used again in solvent dewaxing process.

The material evidence for the wax finish on ancient marble statues, known as ganosis, is scarce and controversial, although Greek and Latin sources describe the recipes and cultural value of this treatment. The surface treatment of a colossal Roman head from the Roman theatre of Dougga (Tunisia), dated to the end of the second century CE, is studied by a multi-analytical protocol (video-microscope, cross section, and time-of-flight secondary ion mass spectrometry of one sample). The results of this physico-chemical analysis and the comparison with ancient recipes, prove the use of ganosis on a Roman statue and explore, for the first time, the application of the recipes described in ancient sources. This result shows the potential of the Time-of-Flight Secondary Ion Mass Spectrometry analysis, detecting at the same time organic and inorganic materials and their stratigraphy, to study the ancient recipes.