colourless glass

The transepts have rose windows in yellow, brown, green and colourless glass.

Manganese has its own purple colour which can balance out the iron colour to make colourless glass.

Trace element analysis of colourless glass showed these were made using sands from different sources and giving some support to the de-centralised production hypothesis.

It is used in small quantities to counteract the blue colour due to cobalt impurities and so to create (apparently) colourless glass.

Earlier examples were made of clear greenish, brownish or almost colourless glass, while later on they often had green, amber, blue or wine-purple colour.

Bohemian glass-workers discovered potash combined with chalk created a clear colourless glass that was more stable than glass from Italy.

The slightly higher amounts of iron in the Early Anglo-Saxon glass results in a colourless glass, with a green-yellow tinge.

From around 70 AD colourless glass becomes the predominant material for fine wares, and the cheaper glasses move towards pale shades of blue, green, and yellow.

Thus a variety of colours can be produced and experimentation allowed the glass-makers to progress from the early muddy green/yellow/brown colours towards clear-coloured and colourless glass.

The use of coloured glass as a decorative addition to pale and colourless glasses also increased, and metal vessels continued to influence the shape of glass vessels.

However, during the last thirty years of the 1st century AD there was a marked change in style, with strong colours disappearing rapidly, replaced by 'aqua' and true colourless glasses.

These were often used for the production of 'white' crystallo glass, a colourless glass or façon de venise, colourless glass of the highest quality.

Gold-band glass is a related Hellenistic and Roman technique, where strips of gold leaf, sandwiched between colourless glass, are used as part of the marbling effect in onyx glass.

By the end of the 18th century, the entire church interior had been painted white, the colourful Medieval stained glass windows had been replaced by colourless glass, and the church looked distinctly Baroque.

A flash is a thin layer of colour applied over a clear base, and this thin layer can be etched away with hydrofluoric acid to show the underlying colourless glass or to give any shade between the original deep blue (or red) to the palest tint.

Debate continues whether this change in fashion indicates a change in attitude that placed glass as individual material of merit no longer required to imitate precious stones, ceramics of metal, or whether the shift to colourless glass indicated an attempt to mimic highly prized rock crystal.

In the Middle East, the glass industry of Syria continued during the Islamic period with major centres of manufacture at Ar-Raqqah, Aleppo and Damascus and the most important products being highly transparent colourless glass and gilded glass, rather than coloured glass.