Practical Test: Thermal Label Overprinting

Overprinting with Thermal Printers: Insights from Our Practical Tests

Whether it’s a best-before date, weight information, or an ingredient list, overprinting labels after production is an important requirement for many of our customers. Two main technologies are commonly used: direct thermal and thermal transfer printing. Direct thermal printing is particularly suitable for short-life labelling. It requires a specially coated, heat-sensitive label material, often referred to as direct thermal paper. The heated printhead reacts with the coating, causing the surface to darken in the areas required. Thermal transfer printing, on the other hand, applies ink from a ribbon directly onto the label, allowing a wide range of materials to be used without them needing to be heat-sensitive. This process produces durable and resistant results, with the quality depending on both the ribbon type (e.g., wax or resin) and the label material.

To provide practical guidance on material performance, we carried out a series of tests in collaboration with Meto. Using their PrintHybrid thermal printers, which support both direct thermal and thermal transfer printing, we focused on thermal transfer overprinting and tested a variety of our standard materials available in the online configurator. Each material was tested with both a wax ribbon and a resin ribbon to observe differences in print quality. These results offer useful guidance, although actual performance may vary depending on your own printer and application conditions.

Wax vs Resin Ribbons: Which One Works Best?

Ribbon selection depends mainly on the label material:

• For film-based labels, a resin ribbon is usually recommended, as wax ribbons are not sufficiently smudge-resistant.
• For paper labels, we generally recommend coated papers for optimal results. However, our tests with the PrintHybrid printers have shown that wax ribbons also perform well on porous papers, producing clear and durable prints even on these more absorbent materials.

Key Factors for High-Quality Thermal Transfer Prints

Beyond ribbon choice, print speed and temperature strongly influence the final result:
Excessive heat combined with slow print speed can damage the material, particularly films, as there is a risk of the printhead burning through the label.
Adjusting temperature and speed also affects print density. Lower temperatures with higher speed can produce lighter grey tones rather than deep black.
Our test results table summarises how different materials performed with each ribbon type and includes practical observations from our trials.

label.co.uk tests Meto PrintHybrid

Compatibility with Other Thermal Printers

The materials used in our tests should be compatible with most thermal printers, including Zebra models. However, we recommend carrying out a preliminary test with your own printer to ensure optimal results. Label rolls can be supplied with a range of core sizes and the correct winding direction for your application. This flexibility helps to minimise downtime and ensures consistent performance when integrating labels into your processes.

Testing Tips and Practical Advice

These results are based on tests with specific Meto printer models and are intended as a guide rather than a guarantee. Actual performance may vary depending on your equipment, settings, and application. For the best results, we recommend testing materials under your own conditions. Our customer service team can provide sample labels and guidance to help optimise your setup.

If you have suggestions for additional materials or use cases to test in the future, we welcome your ideas and will consider them in upcoming trials. You can reach us by telephone on +44 (0) 203 588 1080 or by email: info@label.co.uk.