Challenges in Glass Bottle Coding

As stated above, date coding on glass bottles is essential for industries that produce and package perishable goods, as it conveys important information about the product. This information is useful to both the manufacturer, who uses batch numbers for quality control and logistics purposes, and to consumers, as it clearly states the product’s expiration date. In addition to expiration dates, barcodes and batch numbers are commonly required for traceability and compliance with regulatory standards.

However, as in any mass production, glass bottle coding, or coding on any type of glass container, is all about the volume and the ability to print on as much glass in as little time as possible. It may sound unreal, but it’s not uncommon for bottling companies to date code print on 100,000 bottles every hour. This means that the coding process has to be reliable and fast on top of being legible, ensuring the right data—such as expiration dates and barcodes—is printed clearly for compliance and traceability.

Direct-to-container coding technologies allow manufacturers to apply compliance information directly onto glass bottles, ensuring regulatory marking requirements are met while also supporting sustainability efforts.

Glass bottle coding isn’t as easy as it sounds due to inherent challenges associated with printing on glass.

Printing on glass has its own set of challenges due to the material properties of glass. Many consider glass to be fragile, implying a lack of strength, but that’s far from true. Glass isn’t fragile; it’s brittle and often used for its strength and recyclability. Glass bottles are considered challenging substrates because their non-porous surface and ability to be molded into various shapes make reliable marking difficult.

What makes glass bottle coding so challenging is the fact that glass is a non-absorbent material with a relatively smooth surface and a frequently curved form. This makes the material very hard to print on, as the non-absorbance means that the ink takes longer to dry and cure, the smooth surface might promote smears, and the curved surface area might affect the consistency of the print. The right equipment and technology are critical for effective marking on glass bottles, especially in varied production environments where dust, hygiene, and equipment specifications can impact code quality.

This issue of non-absorbency is mostly solved by using fast-drying inks, while modern printers have their way of dealing with glass bottle curvature, such as using specialized print heads. However, ink selection is also an issue, especially when printing on returnable bottles, which rely on a special, washable ink. The ink has to be durable enough to withstand the rigors of bottling, storage, distribution, transport, and use by the end consumer without being erased in the process. Surface pre-treatment methods like flame or plasma treatment can increase the surface energy of glass, thus improving ink adhesion.

However, once the bottles are collected and returned to the bottling company for reuse, replacing the glass bottle coding with a new expiration date and lot number is necessary.

On high-speed bottling lines, which can process up to 100,000 bottles per hour, features such as instant-drying inks and high-resolution marking are essential to ensure legibility and prevent smudging, maintaining consistent print quality even at rapid production speeds.

Printing on glass bottles isn’t always straightforward. Especially when dealing with different surfaces and environmental factors. Getting good results comes down to using the right equipment, choosing the right ink, and accounting for the environment the bottles are in.

• Fast, consistent printing at high production speeds
• Good adhesion and quick drying on glass surfaces
• Lower maintenance since constant ink flow helps prevent clogging

If you’re interested in glass bottle coding and are in the market for glass bottle coding printer equipment, don’t hesitate to contact KEYENCE and inquire about our line of continuous inkjet printers.