Direct thermal printers have been available for a long time and vary greatly in reliability, robustness and price. They do not have a ribbon and work with heat sensitive (reactive) label material to produce the image. Having no ribbon allows for a smaller, compact size which is often really appealing to users. These printers often need a lot of on-going maintenance with the printing head requiring frequent cleaning to ensure smooth operation. The type of label material that can be used is limited and susceptible to tearing and heat changes. Thick robust stock cannot be used in these printers and label rolls are small meaning more change out of rolls. The label stock may also be problematical in cold climates on some thermal stock and label printers. Also direct sunlight and moderate heat will turn the label black making it difficult, if not impossible to read! There may also only be a limited range of colours of labels available.
What we found: we have used thermal transfer printer in the past. We never believed that they were suitable for test and tag labels, but as our competitors were setting up PATs with them we also did.
Metrotest selected the most robust direct thermal printer we could find and sourced the heaviest direct thermal stock available but found there to be a lot of disadvantages in using a thermal transfer printer and although the size was great, we had unhappy customers and technicians. Our testing technicians found they had to clean the heads after nearly every roll used (125 labels) and on cold mornings had to keep spare rolls in their pockets or the printer would not work.
This label material was not suitable for the range of testing we were conducting, so we changed back to the thermal transfer printer CG2 and replaced free of charge printers belonging to customers unhappy with their direct thermal printer.