Some copper friends ask how to deal with the yellowing of white copper surface? First of all, we need to understand, why it will be yellowing?
White copper surface yellowing, there are generally three reasons:
First, oxidation
White copper in the air, especially in the environment of high humidity, the surface of copper and nickel and other metals will be slow oxidation reaction with oxygen, the formation of a layer of oxide film. With the passage of time, this layer of oxide will gradually thicken, resulting in yellowing of the surface.
If white copper is in a hot environment, the oxidation reaction will accelerate. For example, being in close proximity to a heat source or being subjected to heat during processing may cause the surface of white copper to yellow more quickly.
Corrosion
White copper may come into contact with some chemicals, such as acids, alkalis, salts and so on. These chemicals will react with the surface of white copper, destroying the structure of its surface and causing yellowing. For example, in an environment containing chlorides, white copper is prone to corrosion, producing yellow corrosion products.
Galvanic corrosion may occur when white copper is in contact with other metals and in a humid environment. The potential difference between the different metals causes electrons to flow, which accelerates the corrosion process and causes the surface of white copper to yellow.
III. Dirt and contaminants
Dirt, grease and other pollutants in the air will adhere to the surface of white copper. These dirt will not only affect the appearance of copper, but also interact with moisture and other substances in the air to promote the oxidation and corrosion process, resulting in surface yellowing.
Human fingerprints and sweat stains contain salts, oils and other substances that leave traces when they come into contact with the white copper surface. If not cleaned in time, these traces will gradually accumulate and make the surface of white copper yellow.
Here are some treatments on yellowing for the reference of copper friends only!
Soil method:
White vinegar: pour white vinegar on a soft cloth and then gently wipe the surface of white copper. White vinegar can remove the dirt and oxides on the surface and restore the brightness of white copper.
Lemon juice: citric acid in lemon juice can remove dirt and oxides, and at the same time, it can make the surface of white copper more bright.
Baking Soda: Baking soda is a mild abrasive that removes surface tarnish and oxides and restores the brightness of white copper.
Toothpaste: The abrasive in toothpaste removes surface tarnish and oxides and restores the brightness of white copper.
Professional cleaners can also be used: professional cleaners usually have stronger tarnish removal capabilities and can effectively remove surface tarnish and oxides from white copper.
Caution! Avoid using materials or tools that are too rough to scratch the surface of white copper.
Before cleaning, you can test in an inconspicuous place to make sure the cleaner will not damage the white copper surface.
After cleaning, the white copper surface should be thoroughly rinsed with water and dried to prevent moisture residue from causing the surface to rust again. Regular maintenance of the white copper surface can be done by using substances such as grease or wax to prevent the surface from oxidizing and rusting ......
Polishing method:
Use fine sandpaper (e.g. 2000 mesh or above) to gently polish the surface of white copper to remove yellow oxides. Pay attention to the same direction when sanding to avoid scratches. Then use a soft cloth dipped in polishing paste to polish, so that the white copper surface to restore the luster. For some small white copper jewelry or parts, you can use electric polishing tools for polishing, but pay attention to control the polishing time and strength, so as not to over-polish and damage the surface of white copper.
Focus on prevention and coating protection:
Apply a transparent protective coating, such as varnish and nail polish, on the surface of white brass. These coatings can isolate the air and moisture to prevent oxidized yellowing of the white copper surface. The coating should be even, thin and transparent so as not to affect the appearance of white copper. You can also use professional metal protective agents, such as anti-rust oil, anti-rust paint and so on. These protectants have better protective effect and can protect the surface of white copper for a long time.
