The glass production process

We are passionate about the production of glass and with more than 200 years of experience we have become specialists in the field. We are proud to work with such a fascinating raw material for the purpose of packaging glass. From a grain of sand to a formed vial or bottle, we welcome you to join our exciting production journey.

Putting all raw materials together

At Stoelzle, we use soda-lime-silicate glass, the most popular type of glass used in the industry. The basic ingredients are sand, limestone, soda and recycled cullet. All these raw materials are weighed and then mixed together. The collection of these raw materials is referred to as a batch.

Melting & shaping the glass

All raw materials are melted in a furnace reaching temperatures of up to 1600°C. It can take up to two days for the materials to melt appropriately before the bottles can be made. The liquid glass is directed further into the feeder and at this point the forming process can begin. Glass gobs are cut off where they can then enter the moulds. Cast iron moulds and compressed air, alongside electrical driven equipment comprise an IS machine. This machine performs an impressive conversion of a viscous liquid into a solid object in a matter of seconds.

Glass drop is falling down into the mould

From hot to cold – Annealing & Inspecting

Annealing describes the process in which the glass containers are cooled after the moulding process. This is achieved in a heated furnace called a Lehr where the glass is reheated and then slowly cooled down to room temperature. As the glass containers moves towards the end of the tunnel, the outer surface is treated with a coating which serves as a protective layer. As the conveyor belt leaves the Lehr, the bottles then go through an extensive inspection process. Numerous automated inspection machines are in place where all containers are checked for defects and rectified if necessary.

Packing safely for transport

Glass is a fragile material, which makes packing our products all the more important ensuring they are absolutely safe for transport. We take pride in responsible packaging and remain flexible to the needs and wishes of our customers. We offer large trays, small trays, shrink-packaging, rented trays, carton or plastic layers, Euro or industrial pallets.