How to Protect Galvanized Steel Sheet from White Rust?



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16 March 18
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Special attention needs to be paid to the prevention of white rust on the surface of the zinc coating when storing galvanized steel sheet. White rust will not only affect its appearance, but also decrease the zinc coating, causing the deterioration of product quality. Therefore, white rust is the warning of a poor storage environment which should be handled immediately.

Galvanized Steel Sheets​​

How to Prevent White Rust?

1. Conduct Surface Treatment During Galvanized Steel Sheet Production

Chromatic Treatment

It refers to the method of immersing galvanized steel sheet in chromatic acid solution to enable the surface of zinc coating to be covered by thin film of low activity. Even if the chromatic acid membrane is slightly damaged by hit, the chromatic anhydrous around can dissolve in water to cover the injured area and form new film again. This method can effectively prevent white rust for its self-recovery and protection function.

Chromatic treatment is mainly for applications without painting. Moreover, the surface with chromatic acid coating appears yellow. Do not mix it with rust.

Oiled Treatment

It refers to the method of oiling the galvanized steel sheet to prevent zinc from contacting the air directly. It has a good rust-proof effect for moisture condensation and water immersion. However, oil on the surface of the steel sheet must be wiped off before painting.

Parkerizing Treatment

If galvanized steel sheet is for the purpose of painting, phosphate membrane treatment can be adopted. Phosphate will be firmly attached to the galvanized surface to make it loose and porous, thus providing good footing for coating and getting strong adhesion effect. Users only need to conduct simple degreasing before painting.

Fingerprint-Proof Resin Paint Film Treatment

Cover the galvanized steel sheet with a layer of organic resin paint film to prevent any scratch or bruise during the molding or forging process of steel sheet and roller. It also can avoid finger mark or sweat stain from operation personnel during the machining and handling process, thus preventing rust.

Galvanized Steel Sheets in Coils​​

2. Storage Requirements for Manufacturers

Galvanized steel sheet products should be stored in a well-ventilated area. In the season of high humidity and large temperature difference, drying machine or drying oven can be used to prevent moisture condensation.

3. Storage Requirements for Users

Special attention must be paid when storing the galvanized steel sheet:

Do not be immersed in water;
Store it in a well-ventilated place. Keep it away from the area with large temperature difference or where moisture condensation easily occurs;
If it is immersed by dew or water, it should be dried immediately. Or open the package to ventilate it with an electric fan.

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info@sinowellmetal.com
Fiona.yu@sinowellmetal.com
www.sinowellmetal.com

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