Thermal label printers produce
accurate, high quality images that are necessary for barcode printing and
barcode scanning. When it comes to thermal label printing, two different types
of printing methods are used. They are,
Direct Thermal and Thermal Transfer. People often confuse between direct
thermal and thermal transfer printing and most people don’t have a clear
understanding of which method best suits their needs. Thermal transfer printers
will print both thermal transfer and direct thermal labels. Direct thermal printers
are usually lower cost than the equivalent thermal transfer model. The
following post provides an explanation about direct thermal and thermal
transfer printing technologies, their advantages, disadvantages and how to
understand which printing method will best suit your needs.

What is a direct thermal Printer?

A direct thermal printer uses a
thermal printhead to heat chemically treated, heat activated label stock. The
labels feed through the printer and the printhead heats the surface of the
specially formulated label. The print is created when the label reacts by
darkening in response to the heat from the printer. This type of printing method
is more cost effective as it doesn’t need any ink or printer ribbons and the
printer is usually more compact compared to a thermal transfer printer. Direct thermal printing method is ideal for shorter
life span labels such as transport and parcel delivery labels and food
labelling. It’s also ideal for receipt printing at retail stores since they don’t require a long lifespan. They are also popular for ticketing, short
term price labels and retail industries. Most mobile printers use
direct thermal technology. The primary benefit of using a direct thermal
printer is that it’s less costly and is easier to use compared to thermal
transfer printers. The Main drawback of using direct thermal printers is that the
printed image will fade over time and is sensitive to exposure to heat and
ultra violet light. Typically, direct thermal labels have a life span of
between 6-9 months, depending on the environment and the type of label used.

What is a Thermal Transfer printer?

Thermal Transfer printers use
heat to bond or transfer a thin film of wax or resin coating that’s in a carbon
based printer ribbon onto a label. The ink is absorbed into the label creating a
durable, long-lasting image. The print quality is higher and crisper than a
direct thermal printer labels and therefore makes it ideal for printing high
density bar codes and labels that require a longer lifespan. Thermal transfer
printers use a wider variety of media than direct thermal printers; including
paper, polyester and polypropylene, film and even foil substrates.
Thermal transfer ribbons are available in different
colours, therefore printing is not restricted to just black. This type of
printing method is recommended for labels that need to last longer than 6
months. This type of printing method is ideal for product identification,
inventory labels, asset labelling, tags, certification labels, indoor/outdoor
signage, long term high density barcode labels. The main drawback of using
thermal transfer technology is that it’s more expensive and printer ribbons
need to be replaced. Note when using thermal transfer printing, the specific
label material and ribbon must be carefully matched in order to maximise the
print quality, printer performance and the print durability.

The type of printer that best
suits your needs will depend upon the nature of your application. Consider the
following factors to help you decide which printing methods better suits you. 

• What is the preferred lifespan of the
  labels? For example do they need to have
  a lifespan of more than a year?
  
• Will the labels be exposed to different
  environmental conditions? Such as sunlight, moisture or heat.
  
• Will the labels be subjected to chemicals or
  other forms of abrasives?
  
• Will the labels be subjected to surface friction?
  
• Will you need high density barcodes?

The following summary lists the
main advantages and disadvantages between direct thermal printing and thermal
transfer printing;

Direct thermal printing advantages and disadvantages

Advantages

Does not require toner, ink or printer ribbon

Less expensive than thermal transfer printers

Easier media changeovers

Need little maintenance or replacement of supplies

Disadvantages

Labels discolor or fade after some time

May require more maintenance or printhead replacement

Not ideal for harsh weather conditions

Thermal Transfer Printing advantages and disadvantages

Advantages

Higher quality compared to direct thermal printing

Labels have a longer life span over a year or more

It’s not restricted to only black and white printing

Compatible with a wide variety of materials

Disadvantages

Needs to buy printer ribbon

Expensive than direct thermal printers

Thermal printers are designed to
print within tight tolerance and to produce the exact bar widths to optimise
barcode scanning. In simplest terms the main difference between a thermal
transfer printer and a direct thermal printer is that the thermal transfer
printer require ribbons and a direct thermal printer doesn’t. Thermal transfer
involves the printheads heating the backside of a ribbon to melt and transfer
the compounds into the label in order to create the image. Direct thermal printers use a heat sensitive
label and the printhead heats the heat sensitive media directly and this causes
the colour of the material to change and create the image. Many companies find
that they need both types of printers to efficiently run their business. Finally,
it comes down to what your specific needs are.