The following is an excerpt from the STA Thermal Transfer Printable Overlaminates User Guide:
Thermal transfer printing (TTP) is dictated by print speed and print darkness. Print darkness tells the printhead how much heat to use to burn the dot onto the surface. Print speed is self-explanatory and usually measured in inches per second (ips) or millimeters per second (mmps). The faster you print, the more quickly the printhead must heat up and transfer the heat from the printhead to the ribbon to burn the dot onto the print surface. Static barcodes can be printed using standard print methods, but variable data within a barcode is usually printed with a thermal or digital printer. Variable data barcodes can be used for inventory tracking and traceability, product identication
and/or any other variable data as needed. If variable data is required after the label has been pre-printed, the label can have an overlaminate that accepts the variable data print from a thermal or other digital-type printer.
Companies that print static or variable barcodes typically have a grading system to evaluate the thermal print as this can be crucial for reads at box stores. If the label has an overlaminate that is TT-printable, the print must be readable as it passes through the read station. Readers can be set up to verify barcode readability immediately following the print station. Or, they can be read o-line for qualication and approval and conrmation. Readability of the printed barcode is often graded at many manufacturing plants. The reason – no matter where the product is shipped, traceability must be maintained and this is done through barcodes that MUST be readable at any and all locations where the product is shipped. If the barcode is NOT readable, the company can be ned for not having a readable barcode. This can actually cause an entire shipment to be rejected and returned.
Print durability is another issue that is important for label printers who use TTP technology. Label printers can have the labels pre-printed with company logos or static information, then, at the time of production, thermally print the required data on the label. The print needs to be durable and not scratch o as it moves through the packaging process nor can the print be scratched o later in the process or once it gets into the customer’s hands.
FACTORS THAT AFFECT READABILITY AND DURABILITY
Durability and readability are aected by print speed and print darkness. The other factors that come into play are the ribbons, the printheads and the label surface. For example, a DNP wax ribbon on a Zebra printer will print dierently on an Intermec printer using the same speed and darkness. It doesn’t mean that it won’t print, it just means that the speed and darkness need to be adjusted.”