A Guide to the Art of Thermal Transfer
Thermal transfer labelling is becoming increasingly popular for barcodes and other applications. What is it, how does it work and what are the benefits?
When the SATO corporation produced the very first thermal transfer label printer in 1981, the makers knew they were onto something special, but they could hardly have realised just how huge their innovation would become.
Today, thermal transfer labels are the tool of choice across a variety of industries for creating robust and durable identification labels that can withstand harsh conditions and high temperatures. Here, we take a look at what they are, how they differ from conventional thermal printing and some of the uses to which they are put.
About thermal transfer printing
Thermal transfer printing uses a specialist printer, of the type invented by SATO, in combination with a panel of carbon ribbon, which is the same size as the substrate (the surface onto which you are printing). This ribbon contains wax or resin as the ink. Each dot within the print head individually heats up, melts the wax onto the substrate and applies pressure, to effectively transfer the ink.
When the dot switches off, it immediately cools, and the substrate emerges from the printer completely dry and ready for use.
This differs from conventional thermal printing, which uses a similar principle, but requires a specialist thermal substrate and does not use the carbon ribbon. Thermal transfer printing provides a more durable solution, and is effective even on surfaces that are highly heat sensitive, making it suitable for practically any application.
While the most common type of thermal printing is for the conventional black barcodes, with which we are all familiar, the technology can also be used to create colour images using exactly the same mechanism.
In this respect, the process is not so different to that in an everyday inkjet printer. A monochrome thermal transfer printer has a black panel of ribbon for each page that is being printed, while a colour printer will have either three or four coloured panels for every page.
Uses of thermal transfer labels
Although the process sounds similar, full page printouts using thermal transfer printers cannot be compared in terms of print quality to modern day inkjet of laser printers, so despite our use of the word “page,” they are seldom actually used for full page printing as such.
However, for label printing applications, particularly in industrial settings, they cannot be beaten, due to speed, reliability and the durability and waterfastness of their output.
For these reasons, thermal transfer printing has become the most popular and widespread method for printing barcodes worldwide. For even greater durability, the print can also be laminated.
The technology is also becoming increasingly common in the clothing industry, to print important information such as sizing and care instructions in a way that will withstand the rigours of daily wear and going through a succession of wash cycles.