Thermal Paper Caliper & Basis Weight

This is our last post on the four main aspects of thermal paper that affect its grade.

Caliper: Paper Thickness is often referred to as caliper and is measured in mils or thousandths of an inch. Not matter if you are making books or rolls of paper the caliper and number of sheets or length in feet will determine the thickness of the book or the Outside Diameter of the roll. You may find the need to measure the caliper of the paper you are using to compare it to another product or to a printer specification at some point and it would be good to do that in an accurate number.

The best way to measure would be with a Micrometer which comes in a few styles. The best way to measure paper would be to fold the paper in half, fold it in half again, measure the thickness with your gage and divide by 4. This will give you an average over a few location points and you will not capture a high or low spot.

Basis weight: At times the basis weight of the paper will go hand-in-hand with paper caliper and the basis weight identifies the paper's weight in pounds of a ream (500 sheets) in the basic size for that grade. In metric terms would be the weight in one square meter of paper or f/m2. Basis 70 would mean that 500 sheets 25" x 38" would weight 70 pounds. This is equivalent to 104 g/m2 in the metric system.

Please Note: The basic size is not the same for all paper grades (25" x 38" for coated and offset, 17" x 22" for writing papers, 20" x 26" for cover papers and there are others). Typically if you're working with similar paper your basis size will be the same.

In summary, Sensitivity, Environmental Resistance, Archivability and Caliper are the four main aspects of thermal paper that affect its grade.

Archivability of Thermal Paper

A common concern regarding thermal paper is the length of time the paper's images will last. There are many types of thermal paper designed for a variety of applications. Some products are formulated for long image life and others are designed to balance economy and short duration use. Depending on the type of paper you use, the image could last anywhere from five to 25 years.

The life of the image depends on two critical selections: 1) Ensuring that the paper is matched to the thermal printer such that the image color is fully developed and 2) Selecting the appropriate paper grade to match the needs of the end user. For example, thermal products designed for airline ticketing or long life receipts have significantly improved image stability over products formulated for short duration labels or grocery receipts.

The higher the paper's resistance the longer its image will last (as long as the paper is stored under proper conditions). Standard resistance has a 5 year image life. High resistance has a 7-10 year image life. Ultra high resistance provides the ultimate in image retention with a 20-25 year image life.

Consider using paper with high image resistance if you print:

• ATM Receipts
• Coupons
• Merchandise Receipts
• Receipts needed for expenses or tax reasons
• Gaming, Tote, or Lottery tickets
• Anything with souvenir value such as concert tickets

Or event tickets or passes for:

• Sporting events
• Amusement parks, water slides
• Ski lift tickets
• Hunting or fishing game licenses
• Transportation

Please contact us for more information on thermal paper or any other point of sale application.

The Environmental Resistance of Thermal Paper

When deciding which thermal paper grade is right for you, it's important to consider the environment in which it will be used. The life of any thermal image may be reduced by exposure to heat, humidity, excessive light or contact with chemicals such as plasticizers, oils, solvents, adhesives, water, and some printing inks. If your receipt needs to be kept for a long period of time and winds up in your wallet or purse, on the dashboard of your car, or near a window exposing it to excessive ultraviolet (UV) light, you could have a problem maintaining the receipt's image if not caught in time.

The chemistry combination of the thermal coating is sensitive to UV light and may exhibit some image degradation with extended exposure to office light, or shorter exposure to intense UV light. Some standard paper grades are more sensitive than others. The stability of the image will depend upon the degree to which the image was originally developed, and the intensity of the UV light and the character of UV (% of UV range in a light source). Background development may also occur with prolonged exposure to UV light.

To increase environmental resistance or durability of thermal paper a top coat can be added. This top coat provides extra protection against mechanical stresses, exposure to chemicals or environmental effects. A coating on the back of the paper (back coat) provides additional protection during printing, laminating, and numerous other processes. This higher paper grade is available in various paper weights and thermal activation speeds.

If your application puts this product in harsh conditions or your image needs to last, it would be worth looking into the different qualities of thermal paper available in the market.

Thermal Paper Sensitivity

We’d like to take a more in-depth look at Thermal Paper Sensitivity. Paper Sensitivity is a significant factor when selecting a thermal paper for your application. The sensitivity of a thermal paper refers to the degree to which it reacts to heat (energy). A high sensitivity product will create a better image than a low sensitivity product when given less heat or energy. Images that need to be rich and dark require a high sensitivity thermal paper.

Paper Sensitivity is measured on a Dynamic Sensitivity Curve which is an X-Y graph that measure Energy in mill joules vs. Density. A fully developed thermal image will typically be 1.2 density reading or greater. The dynamic sensitivity curve shows how fast a thermal paper will image or print. It is especially important when selecting the thermal printer, since the higher the dynamic sensitivity of the paper, the faster the printer is able to operate. Dynamic sensitivity curves are available for a complete range of thermal papers.

Application Needs

High Sensitivity:
· Bar codes
· Thermal tickets
· ATM receipts
· Parking receipts
· Ideal for fast speed printers

Alternatively, images that do not need to be as crisp can be created on low sensitivity products.

Low Sensitivity:
· Standard point of sale receipts
· Supermarket weigh scale labels
· Distribution and logistics labels
· Ideal for standard speed printers

Static Sensitivity curves are important when considering using thermal paper in adverse environmental conditions like high temperature and UV exposure. Lower static sensitive thermal paper is needed to ensure that the media will not image due to heat from the sun or any other external source. There are Top Coated sheets available that can help in extreme instances where you might need to balance generating a good thermal image and not getting any unwanted background development.

In general, Paper Sensitivity is a balance of the paper, printer and environment in which they are being used. 80-90% of the applications use a standard grade thermal paper and function well. There are also many thermal printers used in harsh environmental conditions that function very well using special coated thermal products that fit the application.

Variety of Thermal Paper Grades

Following our last post, some of you asked about the availability of higher grade thermal paper. A variety of grades exist. There are four main aspects of thermal paper that affect its grade.

1. Sensitivity—how much energy it takes to image the paper. The higher the sensitivity the better the image.

2. Environmental Resistance—how resistant the paper is to things such as light, heat, and moisture.

3. Archivability Years—the number of years the paper will retain its image(s).

4. Caliper—the thickness of the paper measured typically measured in mils.

POS Supply Solutions offers a wide range of OEM approved direct thermal POS products. Whether your application calls for a standard POS grade, a high durability grade with 25-year archivability, or the use of multi-colored direct thermal, POS Supply Solutions has the thermal paper roll solution for you.

In future posts we will explore each of these aspects in more detail. In the meantime, please contact us if you have further questions about thermal paper.

Why do images fade on thermal paper?

Standard POS grade thermal papers use dye and coreactant technology to form an image. The combination is slightly sensitive to ultraviolet (UV) light and may exhibit some image decline with extended exposure to office light or shorter exposure to intense UV light. The stability of the image will depend upon the degree to which the image was originally developed, the individual product design, the intensity of the UV light and the character of UV (percent of UV range in light source).

Since standard POS grade thermal paper is sensitive to ultraviolet light, it must be stored properly to encourage fade resistance. Thermal documents should be stored in a dark place at a relative humidity between 45% and 65% and a room temperature below 77°F (25°C). If these conditions are met and the recommended equipment is used to create the thermal documents, the images should remain legible for at least five to seven years.

In addition to UV light, exposure to the following materials may lead to image degradation and should therefore be avoided:

• Organic solvents (i.e. Alcohols, Ketones, Esters, and Ethers)
• Cleaning Fluids
• Plasticizers
• Petroleum Solvents
• Wet-type diazo copy paper
• Carbon papers
• Castcoated papers
• Papers containing tributal phosphate
• Dissimilar thermal systems
• Carbonless papers
• Ammonia
• Certain Oils
• Water (prolonged exposure)

Thermal paper comes in a variety of grades. We offer a plethora of paper grades to meet your needs and combat image life issues. Just let us know how we can help you!

Why blog about Point of Sale Supplies?

We receive hundreds of inquiries every year from people just like you who need a particular type of paper, ribbon, or cleaning solution and don’t know where to start. I’ll admit, even after 20+ years in the industry, it can be confusing to identify the exact type of supplies needed for an ultrasound machine, a gas station pump, a credit card terminal, or just a plain old adding machine. That’s where we come in. POS Supply Solutions prides itself on knowing the answers to your Point of Sale questions. If you stump us, we’re committed to finding the answers you need through some good old-fashioned research. Just leave a comment with your question(s) and we’ll get to work!

We also stay on top of economic trends , new POS product releases, and the global marketplace. We’re excited to discuss these things with you (and anything else regarding POS that you’re interested in!) and are dedicated to being your #1 resource when it comes to thermal paper, paper rolls, and all things Point of Sales.