Throughout the centuries in Murano the glass masters produced with glass several different kinds of coloured rods, all meant to be used together by heating them and by constructing a whole mass of glass which is then worked in a final shape. This techniques were widely used until the 16th century, when the downfall of Murano glass industry began.

When it was "rediscovered" by the middle of the 19th century a Venetian antique dealer called Sanfiriquo contracted in such quantities the Murano glass factories for objects made in this technique reproducing the earlier designs that the entire range of different designs was since then called simply Zanfirico.

An especially prized glass paste, invented by Murano glassmakers during the first half of the 17th century. It was given this name because its manifacturing process was tricky and of uncertain success for even the most experienced  glassmaker, and was therefore a ventura or chance. The preparation of 'aventurine' is long and delicate, resulting in the formation of small copper crystals, foliated and shining (stelle or stars, from whence stellaria, as 'aventurine' was also known in the past), and was kept a closely guarded secret across the centuries by a small number of skilled glassmakers. The glass is removed from the furnace in blocks, after having been slowly cooled, and its characteristic appearance can be seriously impaired during remelting. Once cold, it is cut like a hard stone, or worked hot with special care. Ordinary 'aventurine' is a brownish colour with stelle, whilst an even more highly valued type, known as verderame, takes on a copper green colour of superb effect.

AVVENTURINA

BALLOTON

A metal mould, giving a cross-relief effect on glass. Inside the mould are small square-capped "points" (needles) which, when the glass is blown, result in the cross-relief pattern.

With careful handling this depression are kept in place during the blowing and shaping process, leaving a geometrical pattern of great effect.

BOLLINATO

A particular decorative effect used in thick glass and consisting of a myriad of large and small “bubbles”, distributed in layers within the thickness of the glass.

It may obtained with two methods.

The first method requires the glass to be rolled on a plain metal surface covered with small sharp spikes so that, as they print a depression on the glass in its malleable state, it comes out with “holes” which will be then covered with another layer of glass, resulting in air bubbles trapped in correspondence to each “hole”.

The second method involves the use of a conic mould patterned with spikes on the inside, in which the glass is blown, creating the air bubbles that will be covered by a layer of glass.

CALCEDONIO

A vitreous paste with a dark base, red when transparent, with multicoloured veins, imitating a variety of natural chalcedony, zone agate.

Invented in Murano in the mid 15th century, its difficult preparation requires the addition of various metallic compounds to the glass mixture, in specific ways and at specific intervals.

The secret of its manufacture lost between the end of the 18th century and the first half of the 19th , was rediscovered by Lorenzo Radi in the 20h century

FENICIO

A type of decoration obtained by applying the hot vitreous threads of pasta vitrea (opaque coloured glass with a ceramic-like consistency) around the walls of blown glass objects. These threads are then “combed” with a special tool in order to create repeated festoon motifs. Once reheated and blown, these can be incorporated into the wall of the object to produce a smooth surface.

This decorative technique was  introduced into the Murano glasswork at the end of the 16th century, but we do not know what it was called then.

The term fenicio (Phoenician) was adopted during the 19th century when similar decorations were found in pre-Roman, Phoenician and Egyptian glassware.

A refined hot-working technique invented at Murano in the first half of the 16th century. The complex working of "filigree" blown glass objects requires the use of crystal rods prepared beforehand and containing vitreous lattimo (milk glass) or coloured threads in smooth or spiral designs. There are various types: reticello or netted filigree, with a delicate thread net inside the crystal wall; a retortoli, twisted filigree with threads twisted into a spiral pattern (also called zanfirico after the venetian antique dealer Antonio Sanquirico, who commissioned numerous copies of antique glass pieces made using this technique in the first hal of the 19th century).

FILIGRANA

SCAVO

Literally, excavation glass, for the particular finish alike to the antique Roman glass brought to light from excavation.

The characteristic feature of this type of glass, introduced by Cenedese in the 1940s and then developed through the years, is an overall surface rough mat finish, predominantly grey but with splashes of various colours.

The uneven appearance and opaque colour are the results of the reaction of salts and mineral oxides scattered over the surface of the object during the last phase of work.

Sommerso (submerged) is a decorating technique used to obtain several layers of glass in a single object.

This thick glass is obtained by superimposing several layers of cristallo (clear) and transparent coloured glass, still attached to the blow-pipe, and repeatedly immersing the object during the process in the various pots of molten coloured glass.

There are many variations on this technique because some layers of transparent glass can be replaced with other types of glass, for instance bubble glass, gold leaf glass etc., the inclusion of which produces fine chromatic effects.

Sommerso glass was especially popular during the 1930s.

SOMMERSO

ZANFIRICO

The filigree, or reticello, is obtained using slim glass rods containing threads of opaque, usually white, glass. These rods, which are pencil shaped are placed side by side on a refractory plate and heated in the furnace until they melt and incorporate to became a single piece. The "slab" obtained in this way then "wrapped" around a cylinder of clear, incandescent glass so that only the internal thread (white or coloured) are visible. The glass is then blown as usual, and various objects (vases, glasses, etc.) modelled. In the case of the classic reticello technique, the operation described above is completed in two successive hot-working phases,  the result of which is a criss-cross pattern. Considerable skill and artistic talents are needed to carry out this operation successfully.

Among the several designs of Zanfirico canes the most delicate is the half-filigree technique, the final aspect of a glass piece made in this technique is that of a piece completely "wrapped" in glass threads, all very close "packed" together.

GLASS TECHNIQUES