Glass can be blown, pressed and engraved. And there are many other ways of manipulating this material. What effects do the different techniques have? Museum Boijmans Van Beuningen’s collection contains numerous objects that illustrate different traditional glass working techniques and show what is possible with this fascinating material.
An experienced glassblower inflates a glob of molten glass with the aid of a long metal tube. He creates a regular shape by rapidly rotating the blowpipe as he blows; if necessary the shape can be refined with metal instruments. Other pieces of molten glass can be fused to it; this is how a piece like a goblet on a base is made.
The heated glass is often blown in a wooden mould. This mould can be opened and the cooled and hardened glass object can be removed from it. Several products exactly the same shape can be made using this method.
The hot molten glass is poured into a metal mould and if necessary pressed in with a plunger. This can only be done with shapes that ‘release’, in other words can be removed from the mould after cooling without difficulty. This means that the possibilities are limited.
Glass engraving (diamond and wheel)
A glass object can be decorated by scratching a design into it with a hard, pointed object. In the 17th century this was done with a diamond stylus. Any design can be created by this technique - a pattern, a landscape, human figures or lettering - but there is a significant risk that the glass will break. From the 18th century onwards, the designs were usually engraved by holding the piece against a fast-turning wheel. Far less detail can be achieved this way but large surfaces can be ground.
Stipple engraving is a highly specialized technique where a design is built up from tiny dots tapped into the glass with a hard, sharp tool such as a diamond stylus. The engraver can create every conceivable half tone by varying the depth of the dots and the distance between them.
Facets can be ground into a glass object by pressing it against a rapidly rotating disc and adding water and extremely fine sand.
While a piece of glass is still on the blowpipe it remains hot and quite malleable. Expert glassblowers can fuse a layer of glass of another colour around this piece of glass. The glass has to be rotated and blown near the open fire the whole time. The end product will have a two-coloured wall; one colour on the inside and one on the outside. A two-coloured product is made by grinding off or engraving the outermost layer.
Reticello or filigree (filigrana)
Making reticello or filigree is a difficult technique for glassblowers. Extremely fine, thin canes of glass are twisted together while the product is being blown and shaped. The main difficulty lies in keeping the spacing between the canes absolutely regular. A sophisticated, almost graphic effect can be created in the glass by inflating the object more or by rotating it. Well-known examples are wineglasses with twisted stems into which a spiral of white, red or red and white threads has been introduced.
A selection of glass objects
Biography of a Glass
I’m made of glass.
I was born around 1725 in England and then brought to the Netherlands, where I was engraved with a rapidly rotating copper wheel. My engraving shows a coat of arms and two monograms in calligraphy, HMAH and FHR. What do those letters stand for? For the man and woman at whose marriage I once starred? Or am I a testimonial to some other joyful event? Perhaps on that occasion, many people drank from me! But unfortunately I have forgotten that and my memory deserts me about the events after the great party.
At the end of the nineteenth century, when I was more than 150 years old, I came into the possession of a rich Rotterdammer: Elie van Rijckevorsel. He was crazy about me and allowed me to shine among the other special pieces from his collection, on display in his private art room.
In 1910, Elie donated me to Museum Boymans because he felt that more people should be able to look at me, and from that moment on, I had my own inventory number: 604 KN&V. Here I am cherished, inspected, washed, protected and admired in all sorts of different exhibitions.
And now you are looking at me: nice to meet you!