What is the difference between
thermal transfer and direct thermal?
Thermal transfer requires a ribbon to create the image on the
label stock. It has a heated matrix head that melts the wax, wax/resin
or resin ribbon to transfer the pigment to the paper. Direct thermal
papers have a heat sensitive coating on the face of the label
stock and do not require a ribbon. The coating on direct thermal
papers is activated when it comes into direct contact with the
heated matrix head (most of the older fax machines used this technology).
Many of the thermal printers on the market today can be used with
either material. You can identify direct thermal stocks by heating
them with a lighter or putting them on a warmer plate for a coffee
maker. Thermal transfer can be marked or written on by using a
silver coin like a nickel.
How does a thermal printer
sense where to begin printing?
A thermal printer uses one of three ways to
signal when to begin printing.
- Most commonly used is the gap between the
labels, this is generally specified to be between 1/8"
and ¼".
- A sensor notch may be located at one or both
edges of the product. This is the preferred method on tag stocks.
- A black sensor bar may be printed on
the backside of the liner.
In all three of these methods, a sensor light
is used to detect the variation when one of these configurations
passes through the printer. When one of these signals is detected
the printer software is instructed to begin printing the next
label.
What is meant by label repeat
and why is it important?
The "repeat" of a label is the measurement from the
top of one label to the top of the next label. This is the measurement
that is used to determine if tooling is available for printing,
die cutting, perfing and folding the label.
What is meant by the specification
OD?
Thermal labels furnished on rolls must fit in a certain space
inside the printer. The term outer diameter is often abbreviated
as OD and refers to the maximum diameter of a roll that will fit
in the printer. Rolls with an 8" diameter are common in the
thermal market.
My customer is batch processing
and fan-folded products would work better for his need. Is this
possible with thermal labels?
Yes, many thermal printers take either rolls or folds. If the
manual does not mention this fact please call us for assistance.
We can do further checking if needed or send a small stack for
testing.
What is the shelf life of
a label?
Most products are warranted for one year from the date of purchase.
The adhesive may remain usable for a longer period of time but
deterioration of the adhesive becomes more rapid after a year.
Note: Once the label has been applied to the substrate, the life
span is indefinite.
What are the most important
items to know when requesting a quote on a label?
- How will your customer print it? Dot matrix,
thermal transfer, laser, ink jet, etc.…
- What is the label
being applied to? Corrugated, plastic, glass, etc.…
- What is the environment?
Clean, dust, dirt, frost, oils, moisture, etc.…
- What is the application
temperature?
- What is the service
range required?
- Permanent or removable
adhesive? If removable, how long before label will be removed?
- Type of face stock
- Number of colors,
numbering, perfs, slits etc.
- Label dimensions
- width, depth, repeat
- Roll, fold or sheet
- Packaging requirements
Why are there different types
of ribbons for thermal transfer applications?
The type of ribbon to be used is determined by the material being
printed on and the application. Listed below are the most common
types of ribbons and their applications.
- Wax ribbon- general purpose ribbon for most
paper face stocks. Most economical ribbon. Used for shipping
labels, inventory control, retail product labeling, and other
data processing applications.
- Wax/Resin combo- Used when durability is
a factor. Used with a wide variety of face stocks including
coated materials, Kimdura, polypropylenes etc. Used for drum
labels, pallet labels, frozen products and other applications
where smudge-resistance and short term outdoor exposures are
factors.
- Resin ribbon- most durable ribbon of all.
Resists heat, abrasion, oils and solvents. Designed for high-end
synthetic label materials such as polyesters and silver polyester.
Used for nameplates, automotive, asset labels and UL labels.
How wide should a ribbon
be for a thermal transfer label?
To avoid unnecessary wear on the print head, the ribbon should
always be slightly wider than the label carrier.
What are the advantages
and disadvantages of the two types of thermal labels?
Thermal transfer:
- Thermal transfer labels are usually more
economical even when the cost of the ribbons is added in.
- There are many more substrates available
for thermal transfer printing.
- The thermal transfer image is more durable
and stable over time.
Direct Thermal
- This method is often used in retail
applications when changing a ribbon would be inconvenient.
- Higher resolution bar codes are possible
with direct thermal than with thermal transfer.
- IR scanning is possible with direct thermal
labels. This is a method of scanning that can read a bar code
through contaminents such as blood or dirt. This method requires
a special direct thermal face stock.
