Glass - Back to the Future!

Presenting Author:
Pavlína Bozděchová

article posted 01 September 2016

Pavlína Bozděchová

Development of environmentally friendly coloured glass

Květa Sázavová & Pavlína Bozděchová
Preciosa, a.s., Opletalova 3197, 466 67 Jablonec nad Nisou, Czech Republic.

Preciosa is a Czech glass company supplying machine-cut crystal components. It primarily produces semi-finished products for the jewellery and fashion industries. The most popular products include crystal chatons, chaton roses, and glass beads. Our company believes in supporting the preservation of the environment. We enforce environmentally safe working conditions and utilize ecologically responsible technologies.
Preciosa has its own development division with a department for development of crystal and coloured glass. We develop new glass colours, modify the glass composition for new processing technologies and currently eliminate compounds from the glass composition that are toxic to the human body and pollute the environment. Removed compounds have to be replaced by other oxides in order to achieve the same properties and especially the colour of glass.
For objective measurements of colour values, a spectrophotometer with an integration sphere is used; it records a transmission spectrum in the visible range of the electromagnetic spectrum (380 nm to 780 nm). The characterization of the colour is determined by the colorimetric system CIE 1976 (L* a* b*). We measure not only coloured glass but also colour tints with low intensity in crystal glass.
The glass components PbO, As2O3 and CrVI+ have been regarded as environmentally harmful and therefore we produce lead-free, arsenic-free and chrome-free glass. PbO is a compound which is important for achieving desired optical properties and As2O3 has been used as a refining agent; it is now replaced with antimony. In our poster presentation, we compare different spectrum of colours and show how we solve other chemical elements that have to be replaced.