Thermal printing is commonly used in a variety of industries—but which one should you use for your barcode labels? Direct thermal or thermal transfer? We’ll help you answer that question below with relevant details about both print technologies—their features and ideal applications.

What is direct thermal print technology?

Direct thermal is a print technology that utilizes a thermal printer in combination with thermal paper. The thermal paper reacts to heat causing it to change color—generally black/dark gray. The printhead selectively heats and cools to print text and images directly onto the paper.

There are two important things to know about the media when considering using this print technology in a healthcare environment:

1. It is a paper media
2. The paper is reactive to heat

This combination of features makes direct thermal a particularly good match for temporary needs that don’t involve exposure to harsh environments.

Labels printed by thermal direct technology generally struggle to withstand abrasion, chemicals or extreme temperatures. The nature of thermal media makes it especially vulnerable to heat, abrasion, and light.

If you’ve ever scratched a direct thermal printed label or receipt, you’ve likely seen the effect of abrasion firsthand—a black mark will be left behind where you scratched the paper. The darkening of the paper due to abrasion can be particularly troubling if the labels contain barcodes—if a dark mark appears in the wrong place the barcode may become unscannable.

Darkening will also occur with direct exposure to heat—this is what makes thermal printing possible—but it can backfire if high heat exposure is involved in your processes. An entire area on a label can become unreadable.

Additionally, thermal reactive paper is sensitive to light—images printed with direct thermal technology will fade over time as they are exposed to light. This slowly reduces the contrast until your barcodes become unreadable and eventually they may disappear completely.

It should also be noted that direct thermal print technology isn’t able to provide an extremely high contrast image—the darkened paper is generally a deep charcoal grey rather than a pitch black. While this makes little difference to the naked eye, it will affect the ability of a barcode scanner to read the code.

Applications

Direct thermal printing is relatively inexpensive—there is no ribbon required—and may be suitable for temporary identification within the lab or other healthcare facilities.

So what about barcoding assets and samples that are exposed to light and harsh environments or practices? That’s where thermal transfer comes in.

What is thermal transfer print technology?

Thermal transfer barcode and label print technology also uses a thermal printer, but offers more flexibility in media by adding a resin or wax ribbon. The ribbon fuses to the media when activated by heat, and by selectively heating and cooling, the printhead transfers text and images onto the media.

Two major features play into the durability of thermal transfer print technology:

1. It can be applied to an array of media, including specially engineered media
2. The ribbon fuses to the media

Thermal transfer print technology can be printed onto a variety of media—paper or synthetic. While paper isn’t suited to harsher environments, synthetic media can be engineered to perform especially well under specific exposures. Whether your practices require specially engineered media or not, the ability to accommodate a broader range of media ensures your image and label can endure your processes from start to finish.

While we almost always recommend this print technology to our healthcare customers who choose to print on-demand, it has limitations as well. For example, thermal transfer print technology can generally only accommodate one color at a time. Some models, such as the cab XC can utilize two ribbons simultaneously to provide dual color printing, however, if you plan on implementing a more complex color strategy inkjet, pre-printed labels or pre-barcoded labware might be a more suitable option.

Thermal transfer label printing is also slightly more costly than direct thermal print technology, mainly due to the requirement for ribbon, but also in part because you may require specially engineered media to withstand particular exposures. The difference in cost is typically negligible especially if the value of long-term and/or harsh environment exposure is factored in.

Applications

Thermal transfer printing is very adaptive to a wide variety of applications due to its durability and sharp image quality. We recommend this technology to our customers in the healthcare industry mainly due to its flexibility and reliability.

High resolution barcodes printed with thermal transfer technology on the right label stock with ribbon optimized for the application can withstand exposures to a variety of chemicals—from isopropyl alcohol to DMSO—and a broad temperature range—from -196 liquid nitrogen to the autoclave. It’s also very affordable in comparison to other high durability print technologies, making it a good choice whether you need your barcodes to last a few days, or a few years.

Overall, thermal transfer print technology is well suited to just about any healthcare application, though we most often supply thermal transfer solutions to facilities looking to track samples and/or donations in tubes, plates or bags throughout their processes.

As a supplier of barcode solutions to facilities with harsh processes and environments, such as those in research, discovery, and diagnostics, we aim to provide the tools to ensure barcode labels withstand those processes and environments. This is why we stand by thermal transfer print technology, it’s both resilient and budget friendly making it a great fit for labs, storage facilities and blood collection centers alike who need important information to remain legible through processing and storage.

If your facility’s processes aren’t particularly harsh and your application is more disposable, or you have more disposable applications within your facility, whether or not your processes are harsh—you could still benefit from thermal transfer, though direct thermal may also suit your needs.

Your goal in choosing a print technology should be to choose the most suitable one to your processes in order to avoid wasted time, effort and budget in the future. We hope this article helps you make that decision so you can more effectively serve your clients, patients and donors. Leave a comment below if you have any questions about either print technology and feel free to reach out to our team if you have any inquiries about our thermal transfer printing options.