Plastic bottles (PET)

Inkjet printing (CIJ) is the most established technology for variable information on PET bottles and is widely used across the beverage industry. The inkjet printer can print directly on the curved surfaces of the bottle, in different positions (neck, shoulder, bottom) and at high speeds without affecting the production flow.

The choice of ink is absolutely crucial for the result. PET bottles are often exposed to condensation and rapid temperature changes, which makes the surface difficult to mark. The ink used here is quick-drying, has extra strong adhesion and is developed not to smear – even on cold or damp bottles. For dark bottles, pigmented ink can be used for maximum contrast, so that the marking remains clear and legible.

Another advantage is that CIJ is highly adaptable during production changes. The machines can be easily adjusted for different bottle sizes and layouts without stopping the line. This makes the technology cost-effective in productions with many SKUs (unique article numbers).

Labelling is the most versatile option for PET bottles as it combines branding and traceability in the same solution. A label can carry both the design that makes the bottle attractive on the store shelf and the necessary information such as batch number, best-before date and barcodes.

There are several different application methods:

• Wrap-around – a label that wraps around the entire bottle.
• Half or 3/4 wrap-around – perfect for smaller amounts of information or when you want to leave part of the bottle visible.
• Zone labels – where a smaller label is placed on the shoulder, bottom or specific areas of the bottle to complement the main graphic label.
• Print & apply – system where the label is printed and applied in one step.

CO₂ lasers are most commonly used on PET bottles. The marking is sharp and durable, making it ideal for batch numbers, best-before dates and traceability codes that must be legible throughout the product's lifecycle.

An important aspect is that PET plastic comes in different varieties – transparent, colored or recycled – and these react differently to lasers. For transparent PET, a CO₂ laser can create a subtle but clear marking by etching the surface, while colored or pigmented PET often provides higher contrast. For producers using recycled PET (rPET), we at Logimark can optimize the laser settings so that the marking remains clear despite variations in the quality of the material.

The advantages of laser are many:

• Permanent marking that cannot be worn away or erased.
• High operational reliability – no risk of stoppage due to running out of ink or labels.
• More environmentally friendly because the technology does not require consumables.