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Technology Comparison: Direct Thermal vs. Thermal Transfer

02 February 2019
Technology Comparison: Direct Thermal vs. Thermal Transfer

Thermal transfer and direct thermal are two options for printing variable data on tags and labels. IIMAK explains the differences between these technologies and how to select the right print method for your application.

What is direct thermal?

Direct thermal printing uses chemically treated, heat-sensitive label stock that darkens when exposed to heat from the thermal printhead. Leuco dye is the essential ingredient in the chemistry that allows this heat reaction to take place. Direct thermal printers have no ink, toner, or ribbon. This simple design makes direct thermal easy to use. However, because a printed direct thermal stock contains the chemistry to darken throughout its life, this darkening reaction can take place unintentionally whenever the material is exposed to high heat. Similar fading can occur with UV exposure. Direct thermal substrates include a select range of paper and film with varying levels of quality, depending on topcoats.

Direct Thermal Technology

Graphic: Direct Thermal Technology

What is Thermal Transfer?

In thermal transfer printing, a thermal transfer ribbon is required to produce an image on thermal transfer receptive tags and labels. The media and ribbon travel together under the thermal printhead. As the printhead elements are heated, the ink is transferred from the ribbon to the receptive media to produce a printed label. The ribbon contains a backcoat that glides along the printhead and protects it from contact with the label surface extending the printhead life. There are a broad range of media and ink types that can be used to adapt to most any application and durability requirements.

Thermal Transfer Technology

Graphic: Thermal Transfer Technology

How to choose the right technology?

Direct thermal is well-suited for simpler applications that have a short life-span in environments with limited exposure to UV. While direct thermal requires only one media type, the label material is in direct and constant contact with the print head, which can increase wear and shorten the printhead lifespan. By using varying label and ribbon formulations, thermal transfer printing can be used for a variety of applications, from simple everyday printing to harsh environment. Thermal transfer ribbons can more readily withstand heat, sunlight, abrasion and chemical exposure than direct thermal and as a result can produce higher print quality, durability and label longevity.


Summary Comparison
 


Direct ThermalThermal Transfer
Print Quality(+) Print quality can vary depending on grade. Non-topcoated (economy) labels can be a lighter black with hazy print quality that may impact barcode scanability.(+) Sharp, crisp, dark black print quality and highly scanable barcodes with all ribbon qualities.
(+) Color thermal transfer ribbons provide visual cues for identification.
Durability(-) Direct thermal media will darken when exposed to high heat and will fade with UV exposure.
(-) Susceptible to scuffing and marring with abrasion and wear and tear.
(+) The proper label and ribbon pairing can withstand heat, sunlight, abrasion and chemical exposure.
Print Speed(-) Slower print speeds recommended.(+) Faster print speeds possible.
Ease of Use(+) One consumable is simpler to install and manage inventory.(-) Although two components are required, materials are easily single sourced.
Application(-) Short life.(+) Archival quality of which will last well over 1 year.
Media/stock selection(-) Limited range of paper and film stocks available with direct thermal chemistry.(+) Broad range of substrates and ink types to meet application needs.
Maintenance Costs(-) Printhead life is significantly lower. According to the printer OEM, printheads are expected to last 25-50% of the life of thermal transfer printhead.(+) The backcoat of a ribbon protects the printhead from abrasion caused by the stock. This allows a thermal transfer printhead to outlast a direct thermal printhead by 2-4x.


Contact IIMAK with your custom requirements.