Thermal Paper Specifications: Everything You Need to Know

In this article, we will unpack the key thermal paper specifications you need to consider when purchasing thermal paper. It will give you a better understanding of the material and help you make informed purchasing decisions on your next round of thermal paper supply. Let’s start with the basics – what is thermal paper?

What is Thermal Paper?

Thermal paper is a special type of paper that produces text or images when exposed to heat. It eliminates the use of traditional and expensive inkjet printers and refills. Thermal paper is ideal for printing labels, receipts, and tickets due to its durability, reliability, and longevity.

What makes thermal paper unique from other papers? Its layered structure will help you appreciate its best use. Picture thermal paper as a multi-layer cake. Each layer increases its quality and durability. Like any cake, it needs a solid base before you see the bells and whistles – frosting, designs, and extra toppings.

Thermal paper structure Source: Koehler Paper

1. Base paper: The base paper is a component that is strong and durable enough to withstand handling and storage. It’s made from wood-free paper and acts as a substrate for the additional layers.
2. Pre-coat: Stacked on top of the base paper is the pre-coat, which acts as a barrier to ensure the subsequent layers receive a smooth, even application of printed text and images.
3. Thermal coat: This is the most important layer in the thermal paper structure. It basically consists of three elements: color former, acceptor, and sensitizer. These elements produce a chemical reaction under heat when exposed to the printer head. This coat is in charge of the paper’s sensitivity to heat and the sharpness of the prints.
4. Topcoat (optional): Some thermal papers may have an optional topcoat that adds an extra layer of protection against environmental factors such as UV light, oils, and moisture.
5. Backcoat (optional): An optional backcoat layer is applied to the reverse side of the paper. This layer can offer additional protection and improve the paper’s performance by reducing static electricity and friction, which can benefit high-speed printing environments.

Breaking Down Thermal Paper Technical Specifications

There are many thermal paper mills in the world. Although different factories use different standards, the specifications of thermal paper are generally the same. Today, we will use Jujo thermal paper as an example to explain the specifications of thermal paper.

JujoL-KME-60 thermal paper specifications

Thermal paper specifications can generally be divided into three categories: Basic properties, Image properties, and Stability properties. Let’s get started with the basic properties of thermal paper.

Basic Properties of Thermal Paper

1. Grammage

Grammage is the most important parameter you need to consider when buying thermal paper. It refers to the weight of the paper per square meter, measured in grams per square meter (gsm). Knowing the GSM is essential to identifying the paper’s thickness, stiffness, and durability.

A high grammage means it’s thicker and can withstand more handling and environmental factors. For instance, thermal paper with a higher grammage (such as 70gsm or 80gsm) is less likely to tear or crumple, which may be ideal for printing tickets and medical records paper. Lower-grammage paper (such as 48gsm or 55gsm) is soft and lightweight and is mainly used for receipt paper printing.

2. Thickness

Thickness, as the name suggests, means how thick the paper is. It is expressed in micrometers (µm). Thermal paper’s thickness affects its rigidity or flexibility – how long it can be wound onto a roll. Thermal paper’s thickness is usually proportional to its GSM. For example, the 70gsm thermal paper is usually thicker than 55gsm paper.

The downside of thicker paper is that fewer meters of paper can fit on a roll. For example, for the popular 80mm x 80mm thermal paper roll, the 55gsm paper is 80m long, while the 70gsm paper is only 50m long, resulting in a 30m difference in length.

3. Tensile Strength (MD/CD)

Tensile strength means the maximum stress the paper can withstand while being stretched. It is measured in two directions: machine direction (MD) and cross direction (CD). MD indicates how much force the paper can withstand when pulled along its length. CD indicates how much force the paper can withstand when pulled across its width. In short, its strength determines the paper’s resistance to wear and tear, whether in printing, handling, or use.

4. Brightness

Brightness refers to the paper’s ability to reflect light, which affects how clearly the printed image or text appears. This paper property is important because if it has a higher brightness, it results in more clarity and readability in print. This is useful when you’re printing receipts and labels that require visible and legible printed information. Brightness is quantified on a scale from 0 to 100, where a higher number indicates greater brightness. For instance, thermal paper with a brightness rating of 98 is brighter than one rated at 97.

5. Smoothness

Smoothness refers to the evenness and consistency of the paper’s surface. This measurement is taken using something called the BEKK method, which is especially good for checking smoother types of paper. The smoothness of thermal paper plays a crucial role in the quality of printed images and the longevity of the print head. When the paper surface is smoother, it allows for sharper and more precise prints because the thermal print head makes better contact with the paper.

Image Properties of Thermal Paper

6. Image Color

Image color refers to the color that appears on the paper when heated. Most thermal papers produce a black image due to the chemical reactions in the thermal coating layer. However, you can also find options that produce blue or other colors due to different chemical formulations.

7. Image Density

The left one has a higher image density than the right one

Image density in thermal paper refers to the concentration of the printed image on the paper, which affects how dark or light the printed result appears. It is usually quantified by the optical density (OD) of the printed image, which indicates how much light the image absorbs. Higher image density means the image is darker and more intense, while lower image density results in a lighter appearance.

8. Dynamic Sensitivity

Dynamic sensitivity chart

Dynamic sensitivity refers to how well the paper can produce images at varying speeds and energy levels during printing. It measures the paper’s ability to produce consistent, accurate images across varying printing conditions.

A higher dynamic sensitivity means the paper can produce a darker image with less energy, enabling faster printing speeds without requiring adjustments to printer settings. This is crucial in high-speed printing needs, where quick and efficient production is key.

9. Static Sensitivity

Static sensitivity chart

Static sensitivity in thermal paper refers to the temperature at which the thermal paper begins to form an image. It is the temperature threshold at which the thermal coating on the paper starts to react and create a visible image, or simply, it means how hot the paper needs to be before it starts turning black.

The more sensitive the paper is, the lower the temperature needed to create an image. For example, highly sensitive thermal paper tends to change color before use when stored in a warehouse in the Middle East and African countries.

10. Maximum Density

Maximum density is all about producing the darkest possible image on the paper. This high level of darkness ensures optimal contrast and readability, which are indispensable for applications such as barcodes and QR codes.

Stability Properties of Thermal Paper

11. Heat Resistance Background

Heat resistance background describes how well the paper can avoid background discoloration when exposed to heat. This feature helps prevent unwanted marks and keeps the printed information clear and legible, even in high-temperature situations.

12. Heat Resistance Image Loss

Heat resistance image loss refers to the paper’s ability to keep the printed image intact even when exposed to high temperatures. It ensures the printed information remains legible over time, making it ideal for use in environments where the paper may be exposed to heat, such as automotive or industrial settings. With good heat resistance and image loss, you can count on your prints to last, no matter how hot the temperature.

13. Humidity Resistance Background

Humidity resistance background refers to how well the paper can avoid discoloration in humid conditions. This quality helps keep the paper looking clean and the printed information readable, even when it’s muggy. If you’re dealing with a humid environment, having a good humidity resistance background will ensure your paper stays clear and free from blotches.

14. Humidity Resistance Image Loss

Humidity resistance image loss refers to the paper’s ability to keep the printed image intact even in humid conditions. It ensures that your printed information remains clear and lasts longer. With good humidity resistance image loss, you can be confident that your prints will stay legible no matter how damp it gets, such as in kitchens or outdoor places.

15. Light Resistance Background

Light resistance background is all about the paper’s ability to fend off discoloration when exposed to light. It prevents fading and keeps your images clear over time. Imagine having printed information that stays legible even after sitting in sunlight or under harsh lighting. That’s what a good light-resistant background does – it ensures your prints look sharp and readable, no matter how much light they are exposed to.

16. Light Resistance Image Loss

Light resistance image loss is the paper’s knack for holding onto the printed image, even when it’s exposed to light. This means your printed information stays clear and sharp over time, whether in sunlight or other light sources. This feature is perfect for applications where light exposure is unavoidable. It ensures that your prints remain as crisp and legible as the day they were made.

17. Image Stability

Image stability is all about how well the thermal paper can keep the printed image unfaded over time, regardless of the conditions it faces. This means your information stays clear and readable for as long as needed. This is particularly important when you store important archive documents, such as tax or legal documents. At Panda Paper Roll, our thermal paper image life can range from 1 to 10 years, depending on your application.

Final Thoughts: Consider These Specifications When You Buy Thermal Paper

Understanding key specifications of thermal paper, such as grammage, thickness, tensile strength, image density, and others, enables you to make the best choice for your needs. This knowledge guarantees top performance and clear prints while extending the life of your printed materials. It’s all about avoiding those pesky operational issues and keeping customers happy. Investing time in understanding thermal paper specs and choosing a reputable supplier, like Panda Paper Roll, ensures your business operates seamlessly and leaves a lasting positive impression on every customer.