TAR AND PITCH

With regard to coal-derived tar and pitch, the following definitions are appropriate to distinguish them from ostensibly similar materials from other sources and from cmde oil in particular. 

It is incorrect to refer to bitumen as tar or pitch. Although the word tar is somewhat descriptive of the black bituminous material, it is best to avoid its use in referring to natural materials. More correctly, the name tar is usually appHed to the heavy product remaining after the destmctive distillation of coal (qv) or other organic matter. Pitch is the distillation residue of the various types of tar (see Tar and pitch). 

A. J. Hoibeig, Bituminous Materia/s Mspha/ts, Tars, and Pitches, Vols. 1, 2, and 3, Wiley-Interscience, New York, 1964—1966. 

Structural carbon shapes fabricated by heating coke with a mixture of tar and pitches are porous and are made impermeable by impregnation with a resin (usually a phenolic resin). Cashew nut shell liquid resin is used when resistance to alkalis and acids is required. 

Hoiberg, A. J., (ed.). Asphalts, Tars and Pitches, Interscience Publishers (John Wiley) (1965) ANSI/AWWA C213-79, Standard for Fusion Bonded Epoxy Coatings for the Interior and Exterior of Steel Water Pipelines... 

Natural resins Pine resins, sandarac, copals, mastic, dammar, amber, frankincense, benzoe, styrax, myrrh, (plant resins) shellac (animal resin) tar and pitch (from thermal treatment of plant resins or wood) Varnishes, coatings, waterproofing materials, paint binders, ingredients of cosmetic and pharmaceutical preparations... 

Resins and wood from birch, pine and fir were used to produce tar and pitch in various regions of Europe and the Mediterranean [87 92,142 148], both for the production of adhesives and of hydro-repellents and coatings. 

In Roman times tar and pitch from Pinaceae resinous wood were used to treat the inner surface of amphorae to store fluids such as wine [ 145,149] and to seal ship planks [89,144], Heating treatments applied to natural resins and resinous wood profoundly modify the chemical composition of the original material. Diterpenoid compounds undergo aromati-zation, demethylation and decarboxylation reactions, with the formation of new compounds of a lower molecular weight that show a high degree of aromatisation [87,88]. In tar and pitch produced from Pinaceae resin and woods, retene is considered as a stable end product of these reaction pathways and nor-abietatrienes, simonellite and tetrahydroretene represent the intermediates of these reactions [87,89,150]. 

When resin or resinous wood is heated strongly, significant changes in resin composition occur, leading to the formation of tar and pitch. Chemical changes... 

Beck, C.W., Stout, E.C. and Janne, P.A. (1997). The pyrotechnology of pine tar and pitch inferred from qualitative analyses by GC-MS and carbon-13 NMR spectrometry. In Proceedings of the First International Symposium on Wood Tar and Pitch, Biskupin, Poland, ed. Brzezinski, W. and Piotrowski, W., State Archaeological Museum in Warsaw, Warsaw, pp. 181-192. 

Weiner, J. (1999). European Pre- and Protohistoric tar and pitch a contribution to the history of research 1720-1999. Acta Archaeometrica 1 1-109. 

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