How to Store Thermal Paper and Labels

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Improper storage of thermal paper and labels causes degradation and compromises paper’s print quality and longevity. Exposure to high temperatures and humidity causes fading, smudging, or complete loss of print clarity. Prolonged exposure to light or certain chemicals can darken thermal paper before use.

This guide outlines storage methods for preserving the quality of thermal paper and labels.

Let’s begin by reviewing factors that damage thermal paper and labels.

Factors Affecting Thermal Papers and Labels

Factors that degrade the physical structure of the thermal paper and the thermal coating are.

Heat

Thermal paper is designed to react to heat. When exposed to temperatures around 60°C (140°F) or higher (activation temperature), the paper’s coating changes colour, which is how images or text are printed.

The paper can develop unwanted marks or discolouration if stored near heat sources like radiators or direct sunlight.

Even at temperatures below 60°C (140°F), prolonged exposure to heat can cause the print to darken or gradually fade.

Light

UV Light: UV light from the sun or office fluorescent lights can slowly fade and discolour thermal paper within a few months.

Over a few years, this exposure can lead to significant fading, making documents unreadable.

Indoor Lighting: Although less intense than sunlight, prolonged exposure to indoor lighting can still affect the paper over time.

Humidity and Moisture

Thermal paper is sensitive to humidity. High humidity above 60% can cause the paper to absorb moisture, leading to curling, smudging, or blackening. Direct exposure to water or other liquids can cause immediate damage.

Shelf Life

Under optimal conditions, thermal paper typically has a shelf life of 7 to 10 years for printed thermal printers and 5 to 7 years for unprinted paper.

However, exposure to heat, light, and humidity can shorten the lifespan significantly.

Chemical Exposure

Chemicals found in vinyl, plastics, shrink wraps, adhesives, carbon papers, organic solvents (including alcohol), cleaning fluids, petroleum solvents (including gasoline), ammonia, and oils can react with the thermal coating on paper and labels.

This reaction causes the coating to soften, become sticky, or discolour, leading to smudging, image distortion, or making the labels unusable.

It’s important to store thermal papers and labels away from these chemicals and in containers made from polyethylene or polypropylene.

How to Store Thermal Papers and Labels

To ensure your thermal papers and labels stay in good condition, follow these storage tips:

Care for Unimaged Paper
- First-In-First-Out (FIFO): Always use older paper stock before newer ones to ensure the thermal coating doesn’t degrade.
- Keep in Original Packaging: Unimaged thermal paper should stay in its original packaging. Mixing different types of thermal paper can affect each other’s coating, causing damage.
Control Temperature
- Optimal Range: Store thermal paper and labels in a cool environment, ideally between 15°C to 25°C (59°F to 77°F). Avoid placing them near heat sources such as radiators, heaters, or direct sunlight.
- No Heat Sources: Exposure to temperatures around 60°C (140°F) or higher causes thermal activation, which can either darken the whole paper or create dark spots. If thermal paper is left near a direct heat source for a few hours, it becomes unusable for printing.
- Avoid Temperature Fluctuations: Thermal fluctuations degrade thermal paper by causing fading, darkening, or blurring due to repeated activation of the heat sensitive coating and weakening of the paper structure. If thermal fluctuations occur below the activation temperature, they generally do not trigger the thermal coating. However, repeated fluctuations can still cause the paper to degrade over time.
Manage Humidity
- Ideal Humidity: Maintain a relative humidity level of 45% to 65%. High humidity can cause the paper to absorb moisture, leading to curling, smudging, or degradation of the print quality.
- Dry Storage: Ensure that the storage area is dry. Use moisture-resistant storage containers or packaging to prevent exposure to humidity.
- Use Desiccants: In areas with high humidity, consider using desiccant packs or humidity-absorbing materials to maintain the optimal moisture level inside storage containers. Silica desiccants are most commonly used. Calcium Chloride desiccants are used for high humidity conditions, and molecular sieves are used for long-term storage.
Protect from Light Exposure
- Avoid UV Light: Store thermal paper in a dark environment to protect it from UV light, which can cause fading or darkening. A file cabinet or a box is ideal for this purpose.
- Use UV-Blocking Materials: If storing thermal paper in a well-lit area is unavoidable, consider using UV-blocking sleeves, containers, or covers to minimise light exposure.
Prevent Chemical Exposure
- Avoid Contact with Certain Plastics: Keep thermal papers and labels away from soft plastics, PVC, plastic folders, and vinyl products. These can release plasticisers that may migrate into the thermal coating, causing it to become sticky or discoloured.
- Avoid Contact with Adhesives: Tapes, stickers, and some packaging materials with adhesives can transfer chemicals onto thermal labels, causing darkening or blurring. Keep thermal labels away from such materials.
Use Protective Storage Solutions
- Protective Packaging: Store thermal labels in protective containers designed for sensitive materials. This helps prevent dust, dirt, and accidental exposure to damaging elements.
- Avoid Overstocking: When storing rolls or stacks of labels, avoid overstacking them to prevent crushing or deforming the rolls, which can affect the print quality.

Heavy-weight thermal paper requires similar storage conditions as standard thermal paper, though its thicker structure provides slightly better durability.

Big box retail stores, logistics hubs, etc use walk-in coolers to store thermal paper and thermal rolls.

The Bottom Line

In conclusion, proper storage of thermal paper and labels is essential to maintaining their quality and usability over time.

By controlling environmental factors like temperature, humidity, light exposure, and chemical contact, you can prevent fading, smudging, and other damage that could disrupt your operations.

Following these tips will not only ensure the longevity of your thermal materials but also save you from potential losses and inconveniences in your business. Store them right, and they’ll be ready when you need them most.