Direct thermal and thermal-transfer printing both use a heated print-head to print on blank labels. However, with direct thermal printers, the print-head must be in direct contact with the label material, while thermal-transfer printers use an ink ribbon to print, made of wax or resin, and this is what comes into contact with the heated print-head.
As such, direct thermal applies heat directly to the label, which reacts with the label’s coating to generate a printout, whereas thermal-transfer printers apply heat to the ribbon, allowing the ink to then be transferred to the label.
What is Thermal-Transfer?
Thermal-transfer printing uses a ribbon to print information on labels.
The heated print-head is used to melt the ink coating of the ribbon, transferring it to the label. Since the label itself is not reactive, the print produced by this method is much more stable and a lot more durable. The ribbon is typically composed of either resin or wax, or a combination of the two.
Thermal-transfer labels are usually made from a thermoplastic film, but can be made of paper material as well.
Thermal-transfer printing is the most widely used printing process in the world for printing of high-quality barcodes.
What is Direct Thermal?
Direct thermal printers use no ink, toner, or ribbon.
Direct thermal printing uses heat to selectively activate chemically treated, thermosensitive labels. The printer’s heated print-head comes in direct contact with the label, that has been coated with a material (a leuco dye) specially formulated to change color when exposed to heat. Once heated, the thermosensitive label reacts and darkens, creating the desired print.
As such, direct thermal printers use no ink, toner, or ribbon.
One important consideration when choosing this method is that the print is unstable and prone to fading over time, especially when stored in hot or humid conditions. Scratches can also produce enough heat to create marks on the label and affect the quality of the print.
Generally speaking, thermal transfer labels will last longer and be able to withstand moisture, abrasion, and exposure to UV better than direct thermal labels. Direct thermal labels are a great choice when the labels ae used in controlled environments for simpler applications that have a short life span.
The disadvantage is that the image degrades over time, so direct thermal (DT) labels are primarily used for short-term use. DT labels will fade or brown with age and will even turn black if exposed to heat or strong sunlight.
A thermal printer, however, is inkless. They use heat to print images on the paper, which eliminates the need to spend money on ink cartridges and printing ribbons that tend to run out of ink at exactly the wrong time. By eliminating the need to replenish ink supplies, retailers save big on operational costs.