Address:
Glafo, PG Vejdes väg 15,
SE-351 96 Växjö
SWEDEN

Visitor's address:
Vejdes plats 3

Tel: +46 10 516 63 50
E-mail: info@glafo.se

You find a map at the
"about Glafo" page.

GOLD RUBY (P9905)

The aim is to find additives, which produce the gold ruby colour directly at the forming, to avoid heat treatment of the glass.

Figure 1 Gold ruby-coloured jug.

Background
To colour glass with gold is an environmental friendly alternative but it gives only a specific tint of red, see figure 1. The colour arises when very small gold particles are formed in the glass. The particles grow to exactly the right size when the finished glass is heat treated in a controlled way, see figure 2. To obtain a correct result it is necessary to have the right time and temperature for the heat treatment and a base glass with the appropriate composition. Thus, gold ruby red is not quite easy to produce.

Figure 2 Annealing colours like the gold ruby are formed when colloidal particles during heat treatment are growing to such a size that colours appear. The size of particles yielding colour is between 10 and 80 nm.

To be able to understand and control the gold ruby it is necessary to understand the fundamental processes, which are affecting the forming of the gold ruby, i.e. the solubility, the core forming ability and the gold growth.

For the first part of the project we used a commercial glass. The ratio between gold and selenium content was varied and so were the time and temperature of the heat treatment.

For the second part we used a simplified glass composition. That makes it easier to study the influence of separate components on the development of the gold ruby colour. The studied components are: selenium, tin, antimony, lead, bismuth, titanium and iron.

When using the simplified glass and adding only gold and selenium the right colour was achieved directly at the manufacturing. Selenium is the additive, which has shown to be of the greatest importance to achieve gold ruby red. However, it is not made clear how the selenium is functioning.

CURRENT PROJECTS