Why is my electroplating flaking off?
By Smart Water Tech Allen Huang 2024-09-27
Electroplating is the most common surface treatment process for faucets. Why do some faucets have blistering, peeling or even rust on the surface of the electroplating layer after only using it for a while?
Some faucet manufacturers may explain that this is caused by the use environment being too humid. The root cause of this phenomenon is the poor surface treatment process of the faucet.
Brass and stainless steel are commonly used base materials for faucets, and their surfaces need special treatment after processing.
Brass faucets are usually electroplated, while 304 stainless steel faucets are mostly brushed.
Electroplating, mirror effect
Brushed, frosted effect
Why does the faucet need surface treatment?
1. Improve aesthetics
The electroplated surface has a crystal-clear mirror texture and can be used as a mirror, reflecting clearly.
The brushed surface is formed by grinding to form lines, similar to the silk satin effect. Although the brightness is not as good as electroplating, the brushed surface is not easy to leave fingerprints, which is convenient for subsequent cleaning.
2. Improve anti-corrosion performance
Regardless of whether electroplating or matte surface treatment is used, the most practical purpose is to prevent the faucet substrate from being corroded by water and air, causing damage to the substrate and thus affecting the health of the water quality.
Faucet electroplating process
Electroplating is a process that uses the principle of electrolysis to plate a layer of metal or alloy on the metal surface to prevent rust and improve wear resistance.
1. Three-layer electroplating
The brass faucets produced by Smart Water Tech for internationally renowned faucet brands mostly use three-layer electroplating.
Semi-bright nickel, bright nickel, and chromium are plated on the refined copper body.
The nickel layer (including semi-bright nickel and bright nickel) plays an anti-corrosion role. Since nickel itself is soft and dark in color, a layer of chrome will be plated on the nickel layer to harden the surface and increase the brightness.
Low-end electroplated faucets generally have a nickel layer of about 5 microns and a chrome layer of about 0.1 microns. High-quality faucets have a nickel layer of about 15 microns and a chrome layer of about 0.3 microns.
2. Why do we need five-layer electroplating?
Some factories also do five-layer electroplating. Is five-layer electroplating better than three-layer electroplating? Why do we need five-layer electroplating?
Usually, "five-layer electroplating" includes three layers of copper, such as hydrogen copper, pure copper, and acid copper, and then nickel plating and chromium plating.
The problem lies in the substrate. The three-layer electroplating uses a refined copper substrate, while the copper material used for the five-layer electroplating contains more impurities, and there are still bumps on the surface after polishing.
Therefore, it is necessary to electroplate the copper layer again on this copper substrate. Just like we use putty to smooth the wall surface, fill the outer layer of the body to meet the electroplating standard, and then nickel and chromium are plated.
The essence of "five-layer electroplating" is a remedy that has to be used due to defects in the copper substrate and manufacturing process, but it is often used by some factories as a selling point to trick buyers. Due to the high-sounding rhetoric, non-professionals in the industry are easily fooled by the exaggerated propaganda, so be careful to distinguish when purchasing.
3. Electroplating test
How to tell whether the electroplating quality of faucets is high or not?
The industry has a professional test: the acetic acid salt spray test (AASS).
A special salt spray test chamber simulates a high-concentration acidic salt spray environment. Compared with the natural environment, the salt concentration of chloride in the salt spray used in the test is several times or dozens of times that of the salt spray content in the general natural environment, which greatly increases the corrosion rate and can quickly test the corrosion resistance of the product electroplating layer. By conducting a salt spray test on the product, the test results can be obtained quickly and accurately.
The salt spray test standard for electroplated products can be found in GB/T 6461: "Rating of specimens and test pieces of metals and other inorganic coatings on metal substrates after corrosion tests". Whether the electroplating of leading products meets the standards is mainly based on the protection rating; that is, the percentage of the ratio of the corrosion area to the total area is divided into several levels according to a certain method, and a certain level is used as the basis for judging whether it is qualified.
| Defect area A/% | Rating RP or RA | Defect area A/% | Rating RP or RA |
| No defects | 10 | 2.5 | 4 |
| 0 | 9 | 5.0 | 3 |
| 0.1 | 8 | 10 | 2 |
| 0.25 | 7 | 25 | 1 |
| 0.5 | 6 | 50 | 0 |
| 1.0 | 5 |
According to the existing national standard, a faucet electroplating acid salt spray test that reaches level 9 for 24 hours is a qualified product, and some manufacturers with strong technical levels can maintain the electroplating effect at level 10.
Note that the salt spray rating does not mean that the longer the test time, the better the electroplating effect. The key lies in the rating achieved. For example, if it is level 10 for 24 hours and level 9 for 48 hours, then the electroplating effect is level 10, and the time meets the national standard requirements.
If the product can achieve a test time and the highest protection rating that far exceeds the national standard requirements, the electroplating quality is high, it is more corrosion-resistant after installation, and it can remain bright and beautiful for a long time.
3. The faucet wire drawing process
Faucets with stainless steel as the base material, especially 304 stainless steel, generally do not need additional electroplating treatment due to the strong corrosion resistance and rust resistance of the material itself. Instead, they are treated with wire drawing on the surface to make it less likely to leave water stains and traces.
Wire drawing is also called sand sweeping. Through the grinding material, the metal surface is mechanically moved back and forth and chemically corroded so that the surface of the workpiece has a layer of uniformly distributed texture.
Wire drawings can be divided into manual and mechanical drawings.
Common mechanical wire drawings include flat-pressure abrasive belt wire drawings, non-woven roller brush wire drawings, wide abrasive belt wire drawings, and centerless grinding wire drawings.
Different wire drawing methods will produce different wire patterns. Usually, wire drawing patterns can be divided into straight lines, random lines, wavy lines, spiral lines, etc.
For ordinary stainless steel faucet products with no texture, the pre-treatment abrasive belt should reach 400 mesh. For those with texture requirements, the abrasive belt should reach 600 mesh.
Most stainless steel faucets are made using a brushed process. Some of our stainless steel faucets are specially electroplated for beauty and uniqueness.
Some factories use cheaper 201 stainless steel as the base material. Since 201 stainless steel has poor corrosion resistance and may rust after long-term contact with a humid environment, it is also electroplated to isolate water vapor from direct contact with the base material. Pay special attention to this when purchasing stainless steel faucets.
The above is an introduction to the surface treatment of copper faucets and stainless steel faucets.