Will brass lose its luster? Causes of loss, protection methods and remedies
Brass, an alloy composed of copper and zinc, has been widely used in the industrial and decorative fields for its unique golden color and excellent mechanical properties. From ancient coins to modern decorations, the luster of brass has always been its charm.
However, many people will have questions: Does brass tarnish? The answer is yes. Although the luster of brass is beautiful, it will gradually fade due to various reasons. This article will discuss four aspects: the characteristics of brass, the reasons for losing luster, the methods to prevent luster loss, and the treatment methods after losing luster.
1.Characteristics of brass
Brass presents different colors and mechanical properties due to different proportions of its components. Brass with a higher copper content is reddish in color, while brass with a higher zinc content is more pale yellow. Brass not only has good ductility, strength and wear resistance, but also has good corrosion resistance. This makes brass widely used in architectural decoration, musical instrument manufacturing, shipbuilding and other fields.
The luster of brass mainly comes from the oxide layer on its surface. The surface of fresh brass will react with oxygen in the air to form a thin layer of copper oxide. This layer of copper oxide not only protects the brass inside from further oxidation, but also gives brass a unique luster. So does brass tarnish? Of course, this oxide layer is not permanent. It will be gradually destroyed by various factors, causing brass to lose its luster.
2.Does brass tarnish—— Analysis of the reasons for losing its luster
(1) Oxidation
Brass will continuously react with oxygen in the air to form copper oxide. Over time, this layer of copper oxide will gradually thicken, and the color will gradually change from the initial bright yellow to dark red or black, eventually causing the brass to lose its original luster. In addition, if brass is exposed to a sulfur-containing environment, such as hydrogen sulfide, sulfur dioxide, etc., copper sulfide will also be generated, causing the brass surface to turn black.
(2) Acid and alkali corrosion
Although brass has a certain degree of corrosion resistance, it will still undergo chemical reactions in strong acid or alkali environments, resulting in surface corrosion. Acid-base corrosion not only destroys the oxide layer on the surface of brass, but also corrodes the brass matrix, thus affecting its gloss. For example, if brass products are stored in a humid environment containing acidic gases for a long time, the surface will gradually become dull.
(3) Friction and wear
During long-term use, brass products will gradually lose their surface oxide layer due to friction and wear. Although this oxide layer is very thin, it plays a vital role in the gloss of brass. Once the oxide layer is destroyed, the brass matrix will be directly exposed to the air, accelerating the oxidation process and causing the gloss to fade rapidly.
(4) Environmental factors
The gloss of brass is also affected by environmental factors such as ambient temperature and humidity. In a high temperature environment, the oxidation rate of brass will accelerate, causing the gloss to fade rapidly. In a high humidity environment, water is easily condensed on the surface of brass to form an electrolyte solution, which accelerates the corrosion process. In addition, dust and dirt in the air will also adhere to the surface of brass, affecting its gloss.
3.Does brass tarnish——Methods to prevent it from losing its luster
(1) Control environmental factors
In order to maintain the luster of brass products, their storage and use environment should be controlled. The temperature should be kept within an appropriate range and avoid being too high or too low. The humidity should be controlled at around 50% to avoid condensation on the brass surface. In addition, dust and dirt around brass products should be cleaned regularly to prevent them from adhering to the brass surface and affecting the luster.
(2) Prevent acid and alkali corrosion
In order to prevent brass products from being corroded by acids and alkalis, they should be stored in a dry and ventilated environment and avoid contact with acidic or alkaline substances. When using brass products, they should also be avoided from contact with acidic and alkaline substances, such as acidic juice, vinegar, etc. If brass products accidentally come into contact with acidic and alkaline substances, they should be rinsed with clean water in time.
(3) Surface treatment
1) Coating
By performing special treatment on the brass surface, such as coating with varnish or fluorocarbon resin, a protective film can be formed to prevent brass from direct contact with the external environment, thereby maintaining its luster. These coatings not only have good chemical corrosion resistance, but also improve the wear resistance of brass.
2) Electroplating
In addition, a metal film, such as nickel, chromium, etc., can be formed on the surface of brass by electroplating. These metal films can not only improve the beauty of brass, but also enhance its corrosion resistance.
(4) Regular cleaning and maintenance
Regular cleaning and maintenance of brass products is an important measure to maintain their luster. Using a mild detergent and a soft cloth to wipe can remove dust and dirt on the surface and prevent these substances from corroding the brass surface.
4.Does brass tarnish——Treatment methods after losing luster
(1) Mechanical polishing
For brass products that have lost their luster, their luster can be restored by mechanical polishing. Using a polishing machine and appropriate polishing agents, such as aluminum oxide or chromium oxide, to polish the brass surface can remove the surface oxide layer and stains and restore the brass to its luster.
Mechanical polishing can not only restore the luster of brass, but also improve its surface finish and make it more beautiful.
(2) Chemical polishing
Chemical polishing is the process of treating the brass surface with chemical reagents. The surface oxide layer and minor flaws are removed through chemical reactions, so that the brass surface is restored to smoothness and gloss. For example, acidic solutions such as nitric acid and sulfuric acid can be used to corrode the brass surface. By controlling the reaction time and solution concentration, an ideal polishing effect can be achieved.
Chemical polishing is simple to operate and low in cost, and is suitable for the treatment of large quantities of brass products.
(3) Electroplating
Electroplating is a method of depositing a metal film on the surface of brass through electrolysis, which can effectively restore and enhance the gloss of brass. For example, the corrosion resistance and aesthetics of brass can be improved by electroplating metals such as nickel and chromium. During the electroplating process, the brass product is used as the cathode and the plated metal is used as the anode. The current in the electrolyte causes the metal ions to be reduced and deposited on the brass surface to form a uniform metal film.
Electroplating can not only restore the gloss of brass, but also improve its wear resistance and corrosion resistance. It is widely used in the treatment of decorative and functional brass products.
5.Does brass tarnish——Answers to related popular questions
Does brass tarnish? Yes. So will some related jewelry made of brass also lose its luster? With these questions, let’s read on.
(1) Will brass jewelry lose its luster?
○ Pure brass jewelry itself will not fade, but it will turn black or produce green rust due to oxidation, losing its original luster.
○ Sweating and oil stains in summer will cause the surface of brass to rust, affecting its appearance.
(2) Will gold-plated brass jewelry lose its luster?
○The gold plating on the surface of gold-plated brass jewelry will gradually wear away, causing the internal brass to be exposed and oxidized, thus losing its luster.
○ The thickness and quality of the gold plating directly affect its color retention time. The plating with a thickness of 10 microns to 25 microns is more durable, while the plating below 0.18 microns is easy to fade.
○ Chemical substances, sweat, friction and humid environments will accelerate the wear and oxidation of the gold plating.
(3) Will silver-plated brass jewelry lose its luster?
○ The silver-plated layer on the surface of silver-plated brass jewelry will also gradually wear away due to friction, oxidation and chemicals, causing it to lose its luster.
○ Similar to gold plating, the thickness and quality of the silver-plated layer determine its color retention life.
(4) Maintenance suggestions:
○ Avoid wearing the same brass or plated jewelry for a long time, especially in hot summer or when doing strenuous exercise or contact with chemicals.
○ When not wearing jewelry, it should be stored in a dry, ventilated place to avoid contact with moisture or chemicals.
○ Regularly wipe the surface of the jewelry with a clean soft cloth to keep it clean and shiny.
○ For brass jewelry, you can use acidic liquids such as lemon juice or vinegar to clean rust, but after cleaning, wipe it dry and passivate it in time to prevent re-oxidation.
6.Summary
Does brass tarnish? Brass will lose its luster. This is an inevitable natural process. However, by understanding why brass tarnishes and taking appropriate care measures, we can slow the process, and when brass has already tarnished, we can also take some remedial measures to restore the luster and beauty of brass products.