In December 2023, UNESCO declared blown glass as Intangible Cultural Heritage of Humanity.[3]​.

Contenido

Actualmente se emplean dos tipos principales de vidrio para la técnica del soplado:.

En ambos las técnicas son artesanales, y requieren de una gran destreza, dada la fragilidad y elevada temperatura del vidrio. Con esta técnica se fabrican el "cristal de Murano".

Borosilicate glass

Commonly known by the trademark name "Pyrex", this glass is used to make pipes, earrings, bracelets, necklaces and jewelry; laboratory instruments, such as test tubes and flasks, and neon tubes in advertising signs.

It is a type of glass that is more resistant than common glass, with very good chemical resistance to water, acids (except hot hydrofluoric and phosphoric acid), salt solutions and organic solvents. It also resists high temperatures without deforming, without doing so below 550 °C.

This artisanal technique uses tools such as butane or propane and oxygen gas machines, tongs, tweezers, blowing rubber, lathes, cutting machines and ovens for tempering glass. The colors of the glasses are obtained from pyrex glass that has been previously colored (at the factory).

In order to make a craft with this technique, you need to melt the Pyrex glass until it reaches about 2000 °C, with which it can be freely molded.[2]​.

To shape the interior volume, a metal tube is often used that pierces the glass, and is inflated by lungs, with the craftsman having to calibrate the necessary air according to the diameter of the bubble or the shape they want to make. When the piece is very large, the lungs are supplied with the help of a compressor.

Recycled blown glass

In order to melt the glass, a temperature of 2000 °C is needed so that it takes on a viscous and crystalline behavior, with which it can be worked easily. Too liquid would be impossible to work with, as would too viscous.

Loads of glass are poured into an oven (in crafts, commonly built with refractory bricks), and after the loads are poured, the "melting" of the glass begins.

In order to take the glass, a hollow cylindrical steel tube or cane is used, previously heated at its end and away from the operator, in order to be at the same temperature as the glass and thus prevent thermal shock, which would make it difficult to adhere to the glass. It is introduced into the melted glass tank of the oven. Once the cane is inserted, the tube is rotated on its own axis in order to obtain the greatest amount of glass depending on the piece to be manufactured.

Once the glass mass has been taken, we proceed to give it a spherical shape on a steel plate, to be able to handle it better (all this by rotating the mass over the width or length of the plate). Once it has the desired shape, the glass ball is blown through the reed to give it the desired dimension. It is then passed into a grain steel mold and the piece is blown forcefully into the mold to give it the desired shape. In larger productions such as glasses, cups, jugs or vases, a mold is necessary to speed up production. When the desired shape is obtained, it is cut from one end with a simple blow on the cane, dropping the piece onto a container previously conditioned with asbestos cloth in its lower part and silica sand of a very coarse grain, all this with the purpose that the part where the tube was joined with the piece of blown glass serves as the mouth of some piece. Once it is deposited, with another tube previously heated to the temperature of the glass in the container at 900 °C, it is taken from the part where the opening is not and is introduced into the oven through one of its mouths in order to heat the piece and thus be able to work on it. Once the desired temperature is reached, the holes are opened little by little with pliers to give it a diameter larger than the initial one. After obtaining the calculated diameter, a piece of wood covered with newspaper (previously moistened with water) is used and the mouth is shaped as desired.

After the piece is finished, the desired applications are placed on it and it is passed to a tempering oven in order to reduce the temperature little by little and this grip has special characteristics (depending on the tempering method) such as hardness and tenacity.

In December 2023, UNESCO declared blown glass as Intangible Cultural Heritage of Humanity.[3]​.