What’s behind a Glass object? Which is the prime material from which an idea of Glass Design takes shape? What defines a Semi-worked? A short journey through sand and rivers and furnaces, to get an idea of what there is behind the creation of a glass work shaped by a Murano Glass Master.

Raw material? The silica sand A Glass Master needs this resource (often as semi-worked) to be able to start off with his/her own artistic creativity. The silica sand is the basis of various types of products. All fine quality products as well as glue, adhesive materials, bituminous sheaths … and Glass. The latter is composed of a homogeneous mixture of various substances, assuming a pasty consistency when heated to high temperatures. Its first component is the silica, in the form of silica sand, to which other substances will be added to facilitate its melting and to make stable (and also particularize) the structure of the manufactured product.

The sand of silica sands? To date it comes from Fontainebleau. A fine and purified river sand that makes the glass transparent without the metal oxides which would instead colour it. During the processing, Glass transparency as well as its colourless determine the purity of the mixture (silica sand + melting substances such as sodium oxide). As a matter of fact some oxides contain impurities that give a more or less intense reflection/colour of green depending on the oxide’s invasiveness. Here is the difference of Fontainebleau’s sand. Its capacity of optimizing the combination of the sand with the melting substances necessary for the process without losing transparency and beauty.

From Flux to Dyes, the Semi-worked takes shape Therefore, to the silica sand one adds the melting substances and then dyes such as metal oxides to obtain well defined shades/colours. For example: cobalt to obtain blue; copper to obtain azure; iron for green … This mixture is put in oven at 1500o , the degrees required to make it workable, in order to create a mouldable mass glass (Semi-worked) which after 6/8 hours of honing will make possible the actual glasswork. The Semi-worked (among which, for example, glass pipes or plate glass) are produced directly in Murano by companies specialized in this field.