Powder Coating Storage: Best Practices for Longevity and Performance

By Trylochan Khadka

Powder coatings are a popular finishing solution known for their durability, efficiency, reusability, environmental benefits, and cost-effectiveness. However, to fully harness their benefits, proper storage is essential.

Maintaining optimal temperature, humidity, and contamination control is key to preserving the performance and application quality of powder coatings. Without the right conditions, issues such as agglomeration (clumps), poor fluidization, and coating failure can arise.

In this article, we’ll explore the best practices for powder coating storage, including the impact of improper storage, transportation considerations, and key preservation techniques.

Why Proper Powder Coating Storage Matters
Powder coatings are complex formulations that contain resins, pigments, and additives designed to function under specific conditions. Improper storage of powder coatings can lead to degradation, causing problems such as uneven application, weak adhesion, and a compromised final finish.

These issues can significantly affect the coating’s durability and lifespan. To avoid these problems, proper powder storage practices should focus on:

• Ensuring consistency: Keeping powders in controlled environments preserves their flowability and particle size, leading to a smooth, even spray.
• Preventing clumping: Managing humidity and temperature fluctuations minimizes moisture absorption, reducing the risk of powder agglomeration.
• Protecting against contamination: Sealing powders away from dust, dirt, and airborne particles maintains purity and coating quality.
• Extending shelf life: Storing powders under stable conditions prevents premature degradation, ensuring they remain usable for longer periods.
• Optimizing application efficiency: Well-preserved powders reduce the risk of feed jams, inconsistent spray patterns, and other equipment issues and disruptions during coating application.

Key Factors in Powder Coating Storage
Every powder coating formulation has a specific shelf life, typically outlined in its Product Data Sheet (PDS). While most powders remain stable for six to 12 months under ideal conditions, some high-performance formulations can last even longer. However, improper storage—particularly exposure to heat, moisture, and contaminants—can cause premature degradation, leading to wasted product and costly rework.

Even before opening the box, poor storage conditions can silently compromise your powder coatings. That’s why it’s crucial to understand exactly how heat, moisture, and contaminants impact your powder coatings—and how to effectively navigate these challenges to ensure optimal performance.

1. Temperature control
Temperature plays a critical role in preserving the longevity of powder coatings. For optimal performance, they between 60 and 77 degrees Fahrenheit (15 and 25 degrees Celsius). But what happens when powder coatings are exposed to extreme temperatures? Let’s explore the potential risks of both high and low temperatures on storage conditions.

Too cold (< 60°F / 15°C)
Storing powder coatings in cold environments doesn’t directly degrade performance, but exposure to very low temperatures can make the powder brittle. When moved to a warmer, humid setting, brittle powder may absorb moisture, leading to potential application issues. To prevent condensation, always allow the powder to acclimate to room temperature before opening.

Too hot (> 77°F / 25°C)
On the other side of the temperature spectrum, when stored in extremely warm ambient conditions, powder may harden or form agglomerates, making it difficult to spray. Excess heat can also affect its chemical stability. Storing powder inside a vehicle or an unventilated area in hot weather can be especially damaging, as temperatures can exceed 140 degrees Fahrenheit (60 degrees Celsius),
rendering the powder unusable. Avoid storing powders in hot shipping docks, delivery trucks, or warehouses without air conditioning.

2. Humidity control
Powder coatings are highly sensitive to moisture, which can lead to clumping and cause performance issues such as poor adhesion, curing defects, orange peel, and difficulties in fluidization during spraying. To prevent these issues, it’s essential to store powder coatings in a humidity-controlled environment, ideally within 40% to 60% relative humidity (RH).

Let’s explore how both low and high humidity levels can impact the quality and application of your powder coatings, as well as some actionable tips to properly control humidity when storing powder coatings.

Low humidity (0%–20%)
When powder coatings are stored in low humidity conditions, electrostatic buildup increases, reducing first- pass transfer efficiency during spraying. The excessive charge accumulation can even lead to sparking in hoses, posing a safety risk. Additionally, back-ionization may occur, causing an uneven coating application that compromises the final finish.

High humidity (80%–100%)
High humidity environments introduce a different set of challenges. Powder coatings can absorb moisture, leading to clumping and poor fluidization, making it difficult to achieve a smooth, consistent spray.

High humidity can also contribute to impact fusion. This happens when powder coatings absorb moisture from the air, becoming more prone to clumping and sticking inside the feed system, hoses, and spray guns. This can increase friction and heat buildup, which leads to clogging and inconsistent powder flow. Additionally, excess moisture can cause powder particles to partially cure or soften, further increasing the likelihood of buildup within the equipment.

Excess humidity also causes electrostatic charges to dissipate too quickly, reducing transfer efficiency and leading to more waste. Furthermore, moisture trapped in the coating can result in film defects such as pinholes, gloss reduction, and adhesion failures, ultimately affecting the durability and appearance of the final product.

To maintain proper humidity levels, here are some suggestions:

• Store powders in a climate-controlled room.
• Keep powders in their original, sealed packaging when not in use.
• A humidity gauge should be used to regularly monitor the storage environment.
• If the area is prone to high humidity, dehumidifiers can help maintain a controlled atmosphere.

3. Protection from sunlight and contaminants
Direct exposure to sunlight can overheat powders, leading to premature degradation. Additionally, direct exposure to contaminants like dust, oil, or moisture can compromise powder flow and application quality.

Best practices to prevent contamination:

• Store powders in sealed containers or their original packaging.
• Store in an enclosed, clean area away from potential pollutants.
• If using a hopper-fed powder system, ensure the hopper is sealed when not in use.
• Always wear latex gloves when handling powder coatings to prevent the transfer of moisture, oils, or contaminants from your hands.

Managing Agglomeration
Even when stored correctly, the physical properties of powder coatings can change over time. Agglomeration can occur due to moisture accumulation or improper stock management, leading to spray inconsistencies such as gun surging. To prevent and manage agglomeration effectively, here are some suggestions to consider:

• Store powder coatings in a dry, ventilated area to minimize moisture absorption.
• Ensure containers remain sealed when not in use to prevent exposure to humidity.
• During transportation and handling, avoid prolonged pressure on lower layers by reversing the back pressure at the base, preventing compression and caking.
• Before application, gently roll the sealed liner to redistribute the powder.
• If moisture has been absorbed, allow the powder to acclimate in an open container until humidity stabilizes.

Shipping and transportation come with their own set of challenges when it comes to powder coating storage. As we’ve already discussed, extreme temperatures and humidity fluctuations can severely affect the performance and usability of powder coatings, making the transportation process even trickier.

To ensure powders arrive in optimal condition, we recommend minimizing exposure to high temperatures during transit. If the powder must travel long distances, it's essential to keep it in a temperature-controlled environment. In hot climates, opting for overnight or express shipping can reduce prolonged heat exposure and minimize risk.

While refrigeration is not typically necessary, temperature control remains vital. Certain specialized powders may even require refrigerated transport if they are particularly sensitive to heat. During the winter months, powders shipped in freezing temperatures should be allowed to acclimate before opening to prevent moisture buildup or damage.

Ultimately, the goal is to minimize transit time—the less time powder coatings spend in uncontrolled environments (such as hot shipping docks), the lower the risk of degradation. For manufacturers and distributors, following these guidelines will help ensure your customers receive products ready for flawless application.

Epoxy-based powders are more sensitive to heat and moisture, making controlled storage essential. Polyester powders are generally more stable but can still degrade if exposed to high humidity for extended periods. Lastly, hybrid formulations can have varying storage requirements depending on the specific chemical blend.

Therefore, referring to the manufacturer’s guidelines for optimal storage conditions and best practices will be your best bet to properly take care of the specific powder formulation you are working with.

Can Powder Recover from Improper Storage?
If a powder coating has been stored improperly, there are some steps to determine whether it is still usable:

• Clumped powder: Sieving the powder may help break up minor clumps, but excessive clumping may indicate permanent damage. For instance, heat-damaged powder that has fused together is usually not recoverable.
• Moisture absorption: Moisture-exposed powder may still be usable if thoroughly dried, but quality may be compromised.
• Manufacturer consultation: If unsure, you can always check with the manufacturer’s technical team to assess whether the powder can still be used.

Practical Powder Coating Storage Tips for End Users
While manufacturers take every step to deliver coatings in peak condition, we can’t forget about the end user. Ensuring proper storage on the user’s end is just as important to maintain performance and durability.

Before using a stored box of powder, follow these best practices to keep your powder coatings in top shape and prevent the aforementioned issues.

1. Inspect the packaging.
Carefully check the box and liner for any tears, punctures, or breaches. A compromised package can allow moisture or contaminants to affect the powder. If any damage is found, transfer the powder to a clean, airtight container before use.

2. Check for clumping and flow issues.
Lightly shake or roll the sealed liner to feel for hardening or large clumps. If mild agglomeration is present, sieving or fluidizing the powder with dry compressed air can help restore its flow. If the powder has absorbed significant moisture and become hard and compacted, it may no longer be usable and should be discarded appropriately.

3. Conduct a small-scale test before full application.
Always spray a test panel before committing to a full-scale application. Observe fluidization, spray consistency, and adhesion to ensure the powder is still in prime condition. If issues arise, adjustments in application settings, humidity control, or pretreatment may be needed.

4. Follow FIFO (first in, first out) inventory management.
Use older powders first to prevent exceeding shelf-life limits. Store newer shipments behind existing stock to rotate inventory efficiently.

5. Regularly monitor storage conditions.
Measure temperature and humidity levels consistently to ensure they remain within recommended ranges.

6. Acclimation.
Before using, allow powder coatings to acclimate to the shop environment for at least 24 hours after removing them from the environmental room. This helps prevent application issues caused by temperature or humidity differences.

Proper storage of powder coatings is essential to ensure their longevity and performance. By following the best practices outlined in this guide, manufacturers, applicators, and end users can maximize the shelf life and efficiency of their powder coatings, reducing waste and ensuring high quality, flawless finishes in every application.

Trylochan Khadka is marketing specialist with TIGER Drylac.