Technical Guide



What is Thermal Paper?

Thermal paper contains a transparent dye which changes to a colour (usually black) when heat is applied. Thermal printing is therefore a different technology which involves printing without ink.

Although most thermal papers produce developed images in black, there are other colours such as blue, red or green which are also available.

For storage for at least 3 years from its manufacturing date, keep it in a dark place with low humidity and below 25 degrees Celsius. Further, you can wrap it up properly to prevent contact with toxins from the environment.



Properties of Thermal Paper :

  • Image Stability - how long the thermal print will be readable when stored in correct conditions.
  • Density - Optical density value measured from thermal printed image.
  • Static sensitivity - The temperature at which the thermal image starts to formulate. (Low static sensitivity means image formation at high temperatures and vice versa)
  • Dynamic sensitivity - The speed and energy level at which thermal paper is printed. (Higher dynamic sensitivity equals better quality.)

Benefits of Thermal Paper Printers :

  • Small, quiet and less susceptible to vibration.
  • Can be installed and used in any orientation.
  • Works regardless of whether the printer is right-side-up, upside down, or sideways.
  • Maintenance costs and total ownership costs are lower.
  • Lesser chance of a paper-jam due to shorter paper path.
  • Requires no ribbons or cartridges.
  • No toner or ink to spill.
  • Can produce images that withstand temperatures up to 270°F (132°C)




Applications of thermal paper :

Point-of-sale receipts such as ATM receipts, bus tickets, railway tickets, boarding passes, retail billing receipts, utility bills, Credit/debit card machine receipts, labelling etc. It is interesting to know that about seventy percent of all thermal paper sold is receipt paper.



Types of Thermal Paper :

1. Standard :
Standard thermal paper is a paper with a minimum caliper of 0.55 micron and a GSM range of 50 and above, which is convenient for use on all available printers and give an image intensity of 1.10+ with DPI of 203.

2. With or without the top coating :
A top coating over the coating of dye protects the dye from damage during handling. The top coating focuses the heat from the thermal print head on the active coating resulting in much sharper print results.They offer resistance to discolouration, fading, water, oils, grease etc. and even increase archival storage for up to 25 years.

3. Paper or Synthetic Media :
A synthetic media such as polypropylene can be used as an alternative to paper. This is usually a premium grade providing higher tear resistance and durability. It also offers resistance to degradation, adverse environmental conditions, etc.

Things to consider before selecting the right thermal paper for you :

It's common for most documents to look perfect when they come out of the printer, but the real test is whether they will hold up over their expected life span.

We can therefore consider the following key factors before choosing a paper :

1. Durability and thickness :
It is no secret that the thicker the paper, the more durable it is. However, a balance needs to be maintained as thicker paper results in less paper roll. This results in more frequent roll changes.

2. Intended lifespan and archive-ability :
Besides heat or moisture, if your paper needs to be archived and stored for long periods of time, the material chosen should have the appropriate lifespan to suit your requirements.

3. Potential exposure to heat or moisture :
If your work involves higher temperatures of exposure to extreme conditions which could result in wear and tear, you choose opt for a synthetic medium that is more resistant.

4. Top coating :
Some thermal papers have a top coat which provides extra protection against environmental exposure. Depending on your requirement, you could opt for a paper with or without the top coat.

BIS (Bureau of Indian Standards) for Thermal Paper :

The Bureau of Indian Standards is the National Standards Body of India under Department of Consumer affairs, Ministry of Consumer Affairs, Food & Public Distribution, Government of India. As the need for thermal paper increased in day-to-day affairs, the Bureau of Indian Standards took up the matter of standardizing and creating common parameters for production of thermal paper in India.

The BIS - Thermal Paper Specification was published in July 2021. It covers various aspects for the collective developments of activities on the lines of standardization, manufacturing specifications and quality certifications for thermal paper.

Click here to read the document published by BIS (Bureau of Indian Standards) for Thermal Paper.




Troubleshooting Thermal Paper Defects based on Caliper of the Paper.

Paper thickness or caliper of paper is measured in microns. Thicker paper rolls tend to be more durable. The chart below shows the various defects when using thermal paper and how to troubleshoot them.

DEFECT DESCRIPTION TROUBLESHOOTING
Poor start When the paper at the start appears different from the remainder of the roll Reduce web cross-deckle caliper variation.
Dished roll A concave or convex misalignment of a progressive roll edge that is immediately observed upon unwrapping Reduce cross-deckle caliper variation.
Telescoped roll A concave or convex misalignment of a progressive roll edge that is observed after the roll has started to be unwound Reduce cross-deckle caliper variation.
Starred end Observing a 'star' pattern that is often symmetrical but frequently missing one or more rays Keep cross-deckle caliper variation to a minimum.
Cracked edge Also known as an edge tear which is a broken edge of the web extending usually for a short distance Often heavy coating or size application is the cause. Maintain uniform sheet caliper at the edge.
Baggy paper Also known as "slack areas", "baggy end", "slack end", "baggy center", or "slack center", this refers to a web with non-uniform draw Normally the thick area results in a baggy area. Reduce cross-deckle caliper variation to a minimum.
Air shear burst Air trapped in the winding roll lubricates the internal layers of paper to the extent that some sections relieve themselves more than others resulting in irregular separation or rupture of the web Minimize cross-machine sheet caliper variation.
Caliper shear burst An irregular separation or rupture of the web, generally occurring between an area of relatively high and low caliper and normally extending some distance in the machine direction Minimize cross-machine sheet caliper variations. Until this can be accomplished, run soft rolls if possible.
Cross-machine tension burst An irregular separation or rupture of the web. While the defect is normally in the machine direction, the fiber separation is in the cross machine direction. Minimize cross-machine sheet caliper variation.
Partial machine-direction tension burst Partial machine direction tension burst refers to a partial, irregular separation or rupture of the web Reduce cross-deckle caliper variation to a minimum.
Rope marks Bands of relatively uniform width around the roll at a constant distance from the edge - Rope marks usually show in the thinner areas. Minimize cross-machine sheet caliper variations, basis weight, moisture, etc.

203, 300 or 600 DPI in Thermal Printing

Just like pixels in an image, printing quality is defined by DPI or dots per inch. Obviously, the more DPI (dots per inch) the sharper is the print quality.

The thermal printer you choose must therefore be able to accommodate your chosen print-head size. While it is common that 203 and 300 dpi print-heads are used interchangeably, 600 dpi print-heads often require a higher quality printer.
203 dpi printing :
Works well on direct thermal and thermal transfer labels, shipping labels with large text & barcodes, all standard paper and synthetic stocks.
It is important to note that small 5 and 5 point text is not recommended and labels 1" x .25" may not print scan-able barcodes.

300 dpi printing :
Works well on direct thermal and thermal transfer labels, shipping labels, asset labels, product labels, all standard paper and synthetic stocks.
300 dpi is the most popular print-head for the majority of label sizes. It is widely used as smaller labels print well and 6 or 7 point text also prints easily.

600 dpi printing :
Works well on labels for electronics, jewellery, eyeglass, small assets and synthetic stocks using resin ribbons.
600 dpi is necessary for printing 5 point text, all types of barcodes and QR codes. Although more expensive, 600 dpi print-heads have a greater lifespan and archive-ability with greater quality print as compared to 203 or 300 dpi.

CONTACT US

India
Unit No. 103, 1st floor ,
Opp Marshal Palace,
Above South India Bank,
Gokhivare, Vasai East-401208.

+91-9823301116

thermpaper@gmail.com

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Membership Number : CPPRI-AI:2022-2

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