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The ''tula'' is an alloy of silver, lead, copper and sulfur, its color is dark gray, almost black. It's characterized by a low melting point (500 °C) compared to the silver one (about 800 °C). The process involves etchings on the silver overlay, which are then filled by the molten alloy, in order to obtain a decorative contrast between the white of the silver and the dark engravings covered by the ''tula'' alloy.  

The ''tula'' is an alloy of silver, lead, copper and sulfur, its color is dark gray, almost black. It's characterized by a low melting point (500 °C) compared to the silver one (about 800 °C). The process involves etchings on the silver overlay, which are then filled by the molten alloy, in order to obtain a decorative contrast between the white of the silver and the dark engravings covered by the ''tula'' alloy.  

La tecnica del ''niello'' è antichissima, e si fa risalire agli egizi. La lavorazione è molto difficoltosa anche quando avviene, come nel caso classico, per rivestire lastre di argento inciso; diventa ancor più complessa nel caso del rivestimento di una stilografica, dove la forma cilindrica rende tutt'altro che semplice fare aderire la lega alle incisioni. Data la sua rarità, ed il grande valore artigianale, le penne realizzate con questa lavorazione hanno un grandissimo interesse collezionistico.

The ''niello'' technique is ancient and dates back to the Egyptians. The processing is quite difficult when is made, as in the classical case, to coat silver engraved plates, It becomes even more complex in the case of the coating of a fountain pen, where the cylindrical shape makes it far complex to put the alloy in to the engravings. Because of its rarity, and the great craft value, fountain pens made ​​in ''tula'' have a great interest to collectors.

==Riferimenti esterni==

==Riferimenti esterni==