Essential Metal Surface Treatment Techniques and Their Working

Jack Lie CNC machining expert

Specialize in CNC Milling, CNC Turning, 3D Printing, Urethane Casting, and Sheet Metal Fabrication Services.

Engineers frequently conduct additional yet essential metal surface treatment techniques to prevent corrosion or improve the metal part’s physical appearance and other properties. Usually, the treatment processes are applied on the external surface of the metal pieces after they are machined or fabricated. While providing the component with enhanced protection against corrosion, these metal surface treatments also add value to the mechanical and electrical properties of the part. Eventually, it further facilitates achieving the desired functionality.

Along the same lines, this article will tell you about different metal surface treatment techniques to improve its quality, primarily focusing on their working or “how-to” aspect. For example, it will elaborate on how to paint anodized aluminum, how to remove paint from aluminum, how to remove zinc plating, how to blacken brass, and how to remove nickel plating. So, here we begin.

How to Paint Anodized Aluminum?

The anodized aluminum can be painted effortlessly due to its adhesive properties, allowing the paint to seep into the surface’s pores. Commonly, the process may take about 6 hours to complete and need a few items such as dish soap, water, brush, etching primer, sandpaper, and oil-based paint. In any case, the critical thing to remember is that the aluminum surface should be thoroughly washed and cleaned through dish soap, water, and brush.

Afterward, etching premier is applied to the surface for better adhesion of the paint, which is coated later. Make sure to let the premier dry completely. By the way, you can use sandpaper to grind away bumps and nicks on the anodized aluminum surface to attain a sleek surface finish. In the end, apply the oil-based paint onto the surface for better adhesion, and again, let it get dried. To add more value to the anodized aluminum, multiple layers of the paint might be necessary.

How to Remove Paint from Aluminum?

Having discussed the painting of anodized aluminum, it is also inevitable to answer how to remove paint from aluminum since removing the paint might be more challenging than applying the paint. The reason is that the paint usually bonds well with many types of metals, including aluminum. With regards to removing paint from the surface of the metal, you may either use home-based remedies or other professional product-based solutions.

There are many approaches used to remove paint from the surface of aluminum, but using baking soda seems the most convenient and efficient solution to the problem. For this purpose, you need a beaker filled with the solution of hot water and baking soda. Then immerse the painted aluminum in the solution, and let it be there for some time. The solution reacts with the metal and allows the paint (enamel, oil-based, or acrylic) to loosen its bond with the aluminum surface. After the immersion of one hour, you can clean the surface of aluminum from the paint.

Though using baking soda to remove paint from the surface of metal offers the best convenience, there remain some other methods as well to remove the paint from the surface of the aluminum.

With a steamer, you need to heat the aluminum bar for 30-40 minutes. Later, the bond between the paint and the surface will weaken, and the paint starts stripping and curling on the surface.

Chemical solutions might not be a popular idea in most cases. Still, they can work amazingly to remove paint from the aluminum surface. For instance, ammonia reacts with aluminum metal. It stabilizes the acrylic emulsion by increasing the pH level that weakens bonds between paint and the surface. That is how the paint can be peeled off the surface of the aluminum.

If you have to remove paint from the aluminum surface immediately with minimum effort, you should employ acidic concentrations. When the acid solution reacts with the painted aluminum surface, it loosens the paint and evaporates. Some acidic solutions to remove paint from the metal surface are concentric nitric, phosphoric, and hydrochloric acids.

How to Remove Zinc Plating?

Zinc plating is an excellent way to protect your metal against corrosion and increase metal’s mechanical and electrical properties. Nevertheless, in some instances, it might be unavoidable to remove the zinc plating from the surface of the metal. In this way, here is the answer to your question: how to remove zinc plating from the metal surface.

There are multiple methods of removing the zinc plating from the surface of the metal, but using muriatic acid (hydrochloric acid) solution comes up as the best solution. Accordingly, the following are the detailed steps to remove zinc plating using muriatic acid:

  • Step 1: The first step is the preparation of the acidic solution. You need to maintain the ratio of 1:10 of muriatic acid with water. It implies that against ten parts of water, there should be only 1 part of muriatic acid. Bear in mind, the greater the volume of solution, the harder it will be to neutralize it later. Anyways, prepare this solution in a bucket by always adding acid to water.
  • Step 2: Add baking soda to the muriatic acid solution. There should be a layer of precipitates in the bottom of the bucket. Then immerse the zinc-plated material in the solution.
  • Step 3: Having waited for 5 to 10 minutes, get the metal out of the solution and wait for three to five minutes. Hold the metal bar with the help of the holder and rinse it well under the water.

How to Blacken Brass?

How to blacken brass? It is a common question that people appear to ask on different social platforms. Instrument makers or people interested in such things are more likely to come up with questions like this. Therefore, here is a detailed answer to how to blacken brass.

Typically, brass is an alloy of zinc and copper. The most common technique of blackening the brass is associated with the coating of copper oxide on it. For this purpose, fully concentrated copper oxide is allowed to react with the small portion of silver and then with the scraps of copper unless the reaction is completed. A small amount of water is also added to avoid crystallization. Later, the piece of brass to be blackened is dipped in the solution for a few seconds. After that time, the part is heated with the flame of the Bunsen burner. This heating continues unless the piece of brass turns black. After that, the excessive oxide is removed from the surface by brushing.

How to Remove Nickel Plating?

Nickel plating is commonly utilized in most household products, from candle holders to sewing machine parts. It is often required to remove the nickel plating; for example, you might not like the embellishment. So, let’s learn how to remove nickel plating from the metal surface.

For this purpose, you need acetone and a bucket in which you could pour the acetone. After that, put the nickel-plated metal in it. For avoiding fuming and smell, it is better to cover the bucket with an aluminum foil sheet or a towel. Keep watching the progress every two hours. The process might take 24 hours for the acetone to remove or loosen the bonds of the plating. In the end, clean the surface gently with the brush, wash it with water, and let it get dried. Without a doubt, this procedure works the best to remove nickel plating from the surface of the metal.

Final Words

Recently, there has been seen considerable progress in metal surface treatment techniques. Undoubtedly, these techniques add massive value to the overall importance of the metal. Amid many other methods, the plating and painting of metal are essential since these techniques are usually cheaper but offer up to the mark results. On the other hand, sometimes, it is also vital to remove the paint or plating from the surface of metals. Whether it is about removing the zinc plating or paint from the surface of aluminum, you might come across such a circumstance.