Cast iron pipe epoxy resin is required to reach 350 hours of salt spray test under EN877 standard, especially DS sml pipe can reach 1500 hours of salt spray test (obtained Hong Kong CASTCO certification in 2025). Recommended for use in humid and rainy environments, especially at the seaside, the epoxy resin coating on the outer shield of DS SML pipe provides good protection for the pipe. With the increasing use of household chemicals such as organic acids and caustic soda, epoxy coating is the best barrier against intrusive substances, while also creating smooth pipes to prevent dirt clogging. The anti-corrosion properties of cast iron pipes make it widely used in laboratories, hospitals, factories and residences around the world.
However, if the paint is not stored properly, it may cause the cast iron pipe to become lighter or discolored after painting, affecting the appearance quality and protective performance of the product.
1. The correct storage method of A1 epoxy paint
A1 epoxy paint is a high-performance protective coating, and its storage conditions directly affect the stability of the coating and the coating effect. The correct storage method includes the following aspects:
1. Temperature control
Suitable temperature: A1 epoxy paint should be stored in an environment of 5℃~30℃ to avoid high or low temperature affecting the chemical stability of the paint.
Avoid extreme temperatures: High temperature (>35℃) will cause the solvent in the paint to evaporate too quickly, and the resin component may undergo polymerization reaction, which will increase the viscosity of the paint or even cause curing failure.
Low temperature (<0℃) may cause certain components in the paint to crystallize or separate, resulting in decreased adhesion or uneven color after painting.
2. Humidity management
Dry environment: The relative humidity of the storage environment should be controlled between 50% and 70% to prevent humid air from entering the paint bucket.
Sealed and moisture-proof: The paint bucket must be strictly sealed to prevent moisture from penetrating, otherwise it may cause paint stratification, agglomeration or abnormal curing.
3. Storage away from light
Avoid direct sunlight: Ultraviolet rays will accelerate the aging of epoxy resin, causing paint color changes or performance degradation. Therefore, the paint should be stored in a cool, light-proof warehouse.
Use dark containers: Some A1 epoxy paints are packaged in dark colors to reduce photosensitivity. The original packaging should be kept intact during storage.
4. Avoid long-term standing
Turn over regularly: If the paint is stored for a long time (more than 6 months), the paint bucket should be turned over or rolled regularly to prevent the pigment and resin from settling and stratifying.
First-in-first-out principle: Use in order of production date to avoid paint failure due to expiration.
5. Stay away from chemical pollution
Store separately: Paint should be kept away from chemicals such as acids, alkalis, and organic solvents to avoid chemical reactions that cause deterioration.
Good ventilation: The storage area should be ventilated to prevent the accumulation of volatile substances that affect the quality of the paint.
The following are the packaging photos of SML Pipe & fittings in DINSEN warehouse:
2. Analysis of the causes of cast iron pipe color lightening or discoloration
If A1 epoxy paint is not stored properly, the cast iron pipe after painting may have problems such as lightening, yellowing, whitishness, or partial discoloration. The main reasons include:
1. High temperature causes resin aging
Phenomenon: The color of the paint turns yellow or darker after painting.
Cause: Under high temperature environment, epoxy resin may oxidize or cross-link, causing the paint color to change. After painting, the paint on the surface of cast iron pipe may lose its original color due to resin aging.
2. Moisture intrusion leads to abnormal curing
Phenomenon: White fog, whitening or uneven color appear on the surface of the coating.
Cause: The paint barrel is not tightly sealed during storage. After moisture enters, it reacts with the curing agent to generate amine salts or carbon dioxide, resulting in fog defects on the surface of the coating, affecting the metallic luster of cast iron pipe.
3. Photodegradation caused by ultraviolet radiation
Phenomenon: The paint color becomes lighter or color difference occurs.
Cause: The ultraviolet rays in the sun will destroy the pigment and resin structure in the paint, causing the surface color of the cast iron pipe after painting to gradually fade or discolor.
4. Solvent volatilization or contamination
Phenomenon: Particles, shrinkage holes or discoloration appear on the paint film.
Cause: Excessive solvent volatilization makes the paint viscosity too high, and poor atomization during spraying leads to uneven color.
Impurities (such as dust and oil) mixed in during storage will affect the film-forming properties of the paint and cause defects on the surface of the cast iron pipe.
3. How to avoid abnormal color of cast iron pipe after painting
Strictly follow the storage conditions and ensure the requirements of temperature, humidity, light protection, etc. Improper storage of cast iron pipe with A1 epoxy paint may cause the color to become lighter, yellower or discolored. By strictly controlling the temperature, humidity, light protection and other conditions, and regularly checking the pt status, coating defects caused by storage problems can be effectively avoided, ensuring that the aesthetics and protective performance of the cast iron pipe are in the best condition.
Post time: Apr-29-2025
