How to make DURAN®

Delivery of raw materials, preparation and melting process

The raw materials (silicon oxide, boron oxide, sodium/potassium oxide mix and aluminium oxide) are delivered in powder form and stored in silos. All our suppliers have been audited and the consistent high quality of the raw materials is confirmed by an analysis certificate.

The batch is mixed fully automatically using highly precise scales and automatically controlled transport and mixing equipment. This precludes composition errors. A proportion of DURAN® cullets is added to the powdered raw material.
The batch is then transported to the melting tank via a conveyor belt. The melting process is the central stage of glass production. The batch is melted at a temperature of approximately 1600°C. The aggregates are heated electrically and operated around the clock.

Forming procedure – glass moulding press

The liquid glass falls into a mould and is pressed into the desired shape using a cooled, hydraulic or servo-electrical driven stamp. DURAN® desiccator bases are manufactured using this procedure, for example.

Forming procedure – rotational blowing machine

This procedure involves blowing liquid glass into a mould. The glass is then reheated to shape the spout, for example. DURAN® beakers, Erlenmeyer flasks and coffee pots are manufactured using this procedure, for example.

Forming procedure – press and blow production

In the case of press and blow production, the liquid glass is made into the right shape by a stamp and a mould. At this point, the thread is then pressed. Using a grappler, the item is then placed in another mould, where it is blown into the final shape. This is how DURAN® laboratory glass bottles with thread are manufactured, for example.

Forming procedure – glassmaker (manual glassware manufacture)

By continuously rotating his pipe, the glassmaker collects a certain amount of liquid glass. He then shapes it by blowing while rotating the pipe at the same time. The glass blower gives the item its final shape by placing it in a closed mould and blowing into it.  This procedure is used to manufacture large-volume DURAN® items.

Post processing and control

Once the products have been moulded, they are cooled and printed using the screen printing method. Ceramic paint is generally used for this, which fuses with the glass to form an inseparable layer when it is baked. The products are then tempered in the cooling conveyor. This burns in the printing paint and removes stresses from the glass. After passing the visual quality control, the products are packed and prepared for dispatch to the customer.