What the markings on bottles mean

Have you ever wondered, what those small numbers, signs and symbols on the bottom of each of our glass containers mean? Are they some kind of secret language to communicate with our customers? Are they just random characters to keep end customers guessing what they might mean?

We have to disappoint you. Each and every single symbol on the base or the heel of Stoelzle Glass Group items has a specific meaning. In this article, we want to explain to you what the symbols are all about so you no longer have to guess.

Where can I find embossed markings?

Engravings are most commonly found on the base or heel of the glass item. Whether the markings are located on the base, the edge, or a combination of the two depends on the shape of the item. For new product developments, we can adjust the location according to customer's wishes.

What do the different markings mean?

Manufacturer's mark: The manufacturer's mark clearly shows the glassworks where each container was produced. Each glassworks uses a specific symbol to enable clear identification. Our Stoelzle glasses are marked with the abbreviation "STO" as standard. Pay attention to the little logo and you will be suprised how often you will find it.

Mould code: One of the most important markings is the mould code. There are different ways to display the mould code. It can be represented in the form of alphanumeric numbers, digital codes or a dot code. The mould code is used to uniquely identify the glass container. Digital and dot codes can be used for automatic sorting at the cold end, while alphanumeric codes require manual sorting.

Standard marking: If a container is standardised, it is either marked with the symbol "M" or the symbol "ε". “M” is used for products whose capacity is less than 40 ml and "ε" for containers that hold more than 40 ml. If this standard is visible on a bottle, the volume must also be indicated.

Volume and fill level: In general, you will find information on the volume on the bottom of each glass bottle or jar. This either can be the nominal volume, the fill level or even both of the mentioned volumes.

Bearing surface: If you look at a glass container from below, the bearing surface is visible. While the bearing surface is generally required for the production process, it may have various shapes. For non-circular containers, 3-point support is often used. For round containers, it is a matter of aesthetics which option is chosen - both ribbed patterns and dots are commonly used.

Additional markings: Depending on a company's individual needs, other types of markings can be embossed to the bottom of bottles. Dab noses are often used to enable precise decoration and labeling. When realising customised product developments, the customer's logo or other symbols can be depicted on the bottle. Whitby worked with Stoelzle to design a unique bottle base in the shape of an ammonite, representing the Whitby coastline.