How long does powder coating last?

Powder coatings are made by mixing specialized resins, pigments, fillers, curing agents, and other additives in a specific ratio. The mixture is then processed through processes such as hot extrusion, crushing, and screening. While they are stable at room temperature, powder coatings do have a shelf life. Expired powder coatings are not recommended for use. However, if the expired coating has been well stored and has not deteriorated, it can be used as appropriate. Let's learn more about the shelf life of powder coatings.

1. Powder Coating Shelf Life

The shelf life of powder coatings is generally 12 months, though longer is possible. Consult the manufacturer for this information. Alternatively, you can test a small amount of powder after 12 months. If no problems are found, continue using the coating. Product characteristics vary from manufacturer to manufacturer, and shelf life may also vary.

2. How to Determine Whether Powder Coatings Are Expired

2.1. Checking the Shelf Life

First, check the production date and expiration date on the powder coating packaging. Generally, powder coatings have a shelf life of 1-2 years.

2.2. Observing the Appearance

Inspect the powder coating for signs of caking, discoloration, or other obvious signs of deterioration. High-quality powder coating should be a uniform powder with no lumps.

2.3. Conduct Small-Scale Testing

If the powder coating has recently expired and appears normal, perform performance tests on a small area, such as adhesion and impact strength tests. If the test results are satisfactory, it can be used as appropriate.

2.4. Check Gloss and Surface Finish

For powder coatings that have been stored for a period of time, check the gloss and surface finish after application. A decrease in gloss and surface finish may be a sign of aging.

2.5. Evaluate Performance

Compare adhesion and flex tests, and observe the product for signs of aging and chalking after several months. High-quality powder coatings have strong adhesion and toughness, and can remain free of chalking and aging for several years.

3. Can Expired Powder Coatings Be Used?

It is not recommended to use expired powder coatings, as the material itself has deteriorated. However, if the powder coating has not been expired for a long time and does not clump, it can be used.

If the paint has recently passed its expiration date, it can be tested on a small scale if no abnormalities are present. If the paint is not past its expiration date, it can be used as appropriate.

Storage of powder coatings significantly impacts its quality. Powders should generally be stored away from sources of ignition and direct sunlight in a well-ventilated area with a temperature below 35°C. Avoid storage in areas susceptible to contamination by water, organic solvents, oil, and other materials. Different types of powder should not be stored together to prevent cross-contamination. Powders from different manufacturers must be recycled during construction, meaning that one batch should be used up before the next. Any unused powder must be kept in a sealed container to prevent contamination.

4. Summary

Powder coatings are made from specialized resins, pigments, and fillers through a specific process. They are stable at room temperature but have a shelf life. The typical shelf life is 12 months, but some may be longer. Consult the manufacturer for details. Samples can be taken for testing and used after the expiration date. Expiration can be determined by checking the expiration date (a maximum of 1-2 years), observing the appearance (no clumping or discoloration is excellent), conducting small-scale testing (testing adhesion, etc.), inspecting the gloss and surface finish, and evaluating long-term performance (for resistance to aging and chalking). It is generally not recommended to use expired paint, but if the expiration date is recent and there is no clumping, a small-scale trial can be conducted. If no abnormalities are observed, use the paint. Store away from sources of ignition and direct sunlight, keep below 35°C, ventilate the paint, and protect against contamination. Store different paints separately from the manufacturer. Reuse the paint during construction, and keep any remaining paint sealed.