GLASSMAKING TERMS

Hot applications. A technique frequently used on Murano involving the application of threads, borders, handles, etc., of various shapes, colours and sizes, during the working of a glass object. Only when the decorations are perfectly even and precise is the final product considered to be a success, from an aesthetic point of view.

An especially prized glass paste, invented by Murano glassmakers during the first half of the XVIIth century. It was given this name because its manufacturing process was tricky and of uncertain success for even the most experienced glassmaker, and was therefore an “adventure” . The preparation of “avventurina” is long and delicate, resulting in the formation within the vitreous mass of small copper crystals, foliated and shining (“stelle”, or stars, from whence the name “stellaria” by which it 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 thefurnace 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” treated with copper is a brownish colour with “stelle”, whereas an even more highly valued type, known as “verderame” takes on a copper green colour of superb effect.

A metal die, giving a cross-relief effect on glass. Inside the die are small square-capped “points” which, when the glass is blown, result in the cross-relief pattern. By covering a PEA stamped in this way with a layer (COPERTA) of glass-using the SOMMERSO technique, for example-an effect is obtained whereby hundreds of minute air bubbles are trapped between two layers of glass.

A particular decorative effect used in thick glass and consisting in a miriad of large and small “bubbles” , distributed in layers within the thickness of the glass. It may be obtained in two manners: the first requires the glass that is being worked to be rolled on a metal surface covered with small sharp “points” so that, as they print a depression on the glass in its malleable state, it comes out with “holes” which will be successively covered with another layer of glass. The result is a real air bubble which remains “trapped” in correspondence to each “hole”. A second system is to use a conic mould patterned with “points” on the inside in which to blow the glass which will come out with “holes”. The subsequent overlay of transparent glass will make the “bubbles” themselves appear.

Semi-finished product consisting in a “stick” of solid or hollow glass successively cut into segments of varying length. They were documented in glassmaking on Murano as early as the XVth century where there is note of a master “canér” (cane- maker). The working procedure is similar to that of bead production. The canes are used not only for the production of minute conterie beads and “lamp-work beads“ but also in the furnace , for example, when the canes are laid parallel side by side or cut into sections and gathered up in hotwork by the still malleable glass. (see also MURRINE)

(literally: coloured in fusion) This expression is still used at Murano. It refers to glass that is coloured whílst still molten, using oxides or mineral salt.

(Cotizza or cotticcia, i. e. not cooked through) A pile of large pieces of glass, usually the size of river pebbles. Cotizzo may also be obtained by pouring molten glass removed from the pots into the CONCHE and then leaving it to cool. During the cooling process the glass contracts and breaks into large pieces. Cotizzo is often re-utilized as a catalyst in the glass mixture. The 1766 Capitulary of the Murano Glass mentions “cotizzi of glass and crystal, as the shapeless glass mass taken from the pot is called”. (see MARIEGOLA)

A type of decoration obtained by applying hot vitreous threads around the walls of blown glass objects. These threads are then “combed” with a special tool in order to create repeated festoons. Once reheated and blown, these can be incorporated into the wall of the vase to produce a smooth surface. This decorative technique was introduced to the Murano glasswork at the end of the 16th century or in the 17th 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. The word graffito was also used (see also VETRI PIUMATI and A PETTINE) and then abandoned.

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 colored threads in smooth or spiral design. 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 half of the 19th century). In recent decades, new and original types of filigree have been invented at Murano. Today the decoration which has parallel rods with straight internal threads worked so that they take on a diagonal slant, is called “half filigree “. Towards the middle of the 16th century, as we are informed by the MARIEGOLA DEI FIOLERI, redexello and retortoli glass objects were already being produced. The filigree, or the 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 become a single piece. The “slab” obtained in this way is then “wrapped” around a cylinder of clear, incandescent glass so that only the internal threads (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 talent are needed to carry out this operation successfully.

A very thin square of pure gold, usually 8cm by 8cm in size, which is “lifted“ by the glass in its molten state during the initial phases of work. The gold may then be covered by a successive layer of transparent glass. If the glass is blown, the gold leaf is pulverized and creates a suggestive effect of “golden dust”. The oldest known Murano glass pieces with gold leaf date back to the second half of the XVth century. The use of silver leaf was introduced in the XIXth century, and also required a successive layer of glass to prevent undesired oxydation.

A decoration consisting in an apparent cracking of the surface of blown glass, obtained by dipping it in water during the working procedure. The reaction which occurs, a sort of “puckering”, produces an “icy” effect. This technique has been known since at least the XVIII th century.

A difficult Murano glassmaking technique. It consisted of welding together two hot open-sided blown glass objects, generally of different colours, along their two edges of equal circumiference, in order to obtain different colour zones in the same object.

Glass covered with a thin vitreous layer of a different color. Frequently used in the XXth century, it is in fact a variation of the so-called” Doublé glass

Diamond point engraving was introduced to Murano for the first time by Vincenzo d’Angelo on mirrors in 1534 or 1535, and in 1549 this same Vincenzo obtained a privilegio or patent for engraving mirrors and blown glass with a diamond point. With the façon de Venise, Venetian style glassware, it spread throughout Europe, especially the Tyrol and the Netherlands. Engraving with a small wheel of abrasive stone or metal derives from hard stone engraving, and was applied with splendid results in Germany and Bohemia during the 17th century. At the end of the same century it was also introduced to Venice with the arrival of the German engravers.

Glass fragments, usually colored, which are “wound” around white glass, giving it the colour of the fragments (the word derives from macchia: stain). Maciette, macie fine: fragments of ever finer grain.

Maestro (master) is a fairly recent word for the person in charge of a team of artistic glassmakers, who is responsible for the running of the PIAZZA, the glass production area. In ancient times he was known as scagner.

A traditional Murano decoration consisting of an ondulating design, made by applying a thread of hot glass to a surface and “pinching” it with BORSELLE DA PISSEGAR. In practical terms, it actually comprises a twist of glass which is placed on the object being made and fashioned into the characteristic ondulating pattern.

A small glass cylinder, often with a small bobéche beneath it, into which candles can be inserted. It may form part of a candlestick or is found on the arms of a chandelier.

Indicates the blowing of a very thin, usually coloured glass, which is successively used in thin blades or scale-like fragments for the decoration of various objects during hotwork.