How to judge the quality of thermal paper?

To judge the quality of thermal paper, one can consider several key aspects, including its appearance, reaction to heat, and light sensitivity. Here are some specific methods to assess the quality:

1. Appearance

• Color: Quality thermal paper should have a slightly greenish tint. If the paper is very white, it might indicate that excessive fluorescent powder has been added to the protective and thermal coatings, which could compromise quality. Bright reflectivity may also suggest an excessive amount of fluorescent agent.

• Uniformity: The paper should appear smooth and even, without noticeable unevenness in the coating. Unevenness in the coating can affect the quality of the printed images.

2. Heat Test

• Fire Test: Using a lighter or match, gently heat the back of the thermal paper. Observe the color that appears after heating. Good quality thermal paper should turn a dark greenish-black, with even color blocks that gradually fade from the center outwards. If the paper turns brown, it suggests an unreasonable thermal formula, which may result in shorter storage life. Additionally, if there are fine stripes or uneven color blocks in the blackened area, it indicates uneven coating.

3. Light Sensitivity Test

• Sunlight Exposure: Another method is to use a fluorescent marker to coat a printed section of the thermal paper and then expose it to sunlight. The faster the paper darkens, the shorter its expected storage life. This test accelerates the reaction of the thermal coating to light, giving an indication of its durability.

4. Physical Properties

While not directly related to the visual or chemical tests, the physical properties of thermal paper are also important indicators of quality. Some key physical properties to consider include:

• Tensile Strength: This measures the paper's resistance to tearing or breaking under tension. Higher tensile strength indicates better durability.

• Tear Resistance: The ability of the paper to withstand tearing forces without breaking. A higher tear resistance is desirable for applications where the paper is likely to be handled roughly.

5. Additional Considerations

• Brand Reputation: Choosing thermal paper from a reputable brand with a proven track record of quality can provide an extra layer of assurance.

• Compliance with Standards: Ensure that the thermal paper meets relevant industry standards and regulations, particularly if it will be used for specific applications such as receipts or labels.

In summary, judging the quality of thermal paper involves a combination of visual inspection, chemical testing, and consideration of physical properties. By paying attention to these aspects, one can select thermal paper that meets their specific needs and ensures reliable performance.