Decorative Engraving Techniques - Cold Glass

Intaglio Engraving

From earliest times, glass makers have decorated their wares using a variety of glass engraving techniques including Intaglio, Stipple, Cameo, Cutting, Etching and Sandblasting.  The earliest glass engraving techniques were borrowed from Mesopotamian artisans who skilfully made Royal and Government Seals by carving designs into extremely hard stone.

Intaglio engraving cuts patterns into glass using a hard material such as flint, diamond-pointed tools or cutting wheels.  Cutting wheels were often made of copper and Emery, an abrasive powder, was used to aid the cutting process.  Wheel cutting was difficult with early glass but enjoyed a comeback in the late 17th. Century when George Ravenscroft developed Lead Glass which is softer and easier to work with. Diamond point Intaglio engraving, used and developed extensively by the Romans, Islamic glass makers and the Venetians, involved scratching a design into the surface of the glass using a diamond-pointed instrument.

Roman period intaglio engraved brooch in amethyst

 

 

 

Glass marriage goblet decorated using stipple engraving

Stipple Engraving

Stipple engraving was developed in Holland around the 1620s whereby a diamond point would be inserted into a hammer and by gently tapping the glass to chip out small pieces, shapes and designs could be created.  The closer together the chips, the more solid the image appears.

Cutting

Cutting, as in Cut Crystal glass, involved cutting grooves to create decorative patterns and shapes using an iron or hard stone cutting wheel plus abrasives.

It was popular with the early Mesopotamian and Roman glass makers but not so much thereafter.

However, it enjoyed a revival once lead glass was developed as this made cutting much easier.

 

Cameo

Cameo describes a technique whereby more than one layer of glass is built up to create an object and then cut back to give distinctive colours and shapes.  Different coloured layers can be built up and fused together whilst cooling.

Once cool, the outer layers can be carved back to reveal the layer or layers below.  The Romans used this technique to stunning effect and the famous Portland Vase (pictured right) is an extraordinary example of the cameo method.  

The same method can be used in reverse whereby an outer shape is created, opened up at one end and, once cool, further shapes can be blown inside to build up layers before carving/cutting to create the colours and shapes.

The famous Roman Portland Vase made using the Cameo process

 

Sandblasting a pattern into glass

Etching

Etching involves covering an object in an acid resistant coating such as wax and carving the desired pattern in the coating.  By dipping the finished item in hydrofluoric acid, the acid burns the decoration into the glass.

Sandblasting

Sandblasting achieves a similar look as etching and has mostly superceded it as a technique since it is safer and less costly. Again the glass is covered to protect it  and the exposed areas subjected to blasts of air containing abrasive material at high pressure to erode the glass.