Chromium plating is a process in which a thin layer of chromium is applied to a metal surface by means of electroplating (usually over a nickel layer). As a result, a decorative metallic sheen is imparted to the coating, it becomes very durable and the development of corrosion is slowed down. However, chrome plating is usually removed for many reasons. For example, despite the hardness of chrome plating, the coating can be damaged by wear and become unsightly, requiring removal. There are several ways to remove chromium plating, some using common everyday materials and others that use highly toxic chemical solutions. Whichever method you choose, take all necessary precautions and follow the appropriate safety rules.
Steps
Method 1 of 3: Removing chrome plating with specialized equipment
This method is used by specialized techniques to physically remove chromium from an object rather than dissolving it chemically. These methods are generally relatively straightforward and the equipment required can be somewhat expensive. In addition, the effectiveness of these mechanical methods can vary depending on the thickness of the chromium and the duration of removal.
Step 1. Use an abrasive machine
Abrasive blasting (eg sandblasting, shot blasting, etc.) is a process in which materials are abraded by the action of a sprayed powder of fine or tiny granules. Most auto dealerships and construction companies have such devices. Prolonged abrasive blasting can remove chrome plating on an object, although later it may be necessary to manually remove chrome from hard-to-reach areas of the object.
- You can use a fairly fine-grained chrome compound (eg 400-grit) so that the chrome spray will not damage the base metal.
- Please note that when using an abrasive blaster, dust and sediment are released into the air by splitting off tiny particles of chromium that can be toxic, so use proper face / mouth protection.
Step 2. Use an ultrasonic cleaner
Ultrasonic cleaners are special devices that use sound waves to clean delicate, difficult items like jewelry. An ultrasonic cleaner can even remove chrome in some situations (especially when the chrome plating has already been weakened by another method). Place the chrome elements in the basket of the ultrasonic cleaner and immerse them in a cleaning solution (often plain water), then start cleaning according to its instructions.
- Use a solvent that can dissolve chromium (such as bleach) instead of water to increase the power of the ultrasonic cleaning. Only do this if the solvent you are using will not corrode the parts of the ultrasonic cleaner as they will react anyway. For example, alkali will react with aluminum containers.
- Please note that while ultrasonic machines come in a variety of sizes, most will only have relatively small items such as jewelry, lug nuts, tools, jewelry, etc.
Method 2 of 3: Chemical Removal
These methods are generally the most powerful and effective methods available for removing chrome plating. Can completely remove thick layer, with high quality electroplated chrome finish. However, these methods also require great care. Many of the chemicals used are highly toxic and / or carcinogenic and there are specific safety requirements for their handling and disposal.
Step 1. Use hydrochloric acid
Hydrochloric acid is highly corrosive. In high concentrations, it can be used to remove chromium plating from metal objects. To remove chromium, the acid solution should be about 30-40%. Follow the steps below:
- Make a 1/3 part hydrochloric acid solution with 1 part water in a container for chemical solutions (such as a heavy-duty plastic bucket, etc.). Alternatively, you can buy a ready-made solution of sufficient concentration.
- Submerge the object in the solution for a while until the chrome is detached.
- Wash object thoroughly with soap and water, and rinse before drying.
Step 2. Use sodium hydroxide (alkali) to separate chromium from ferrous metals and carbon steel
Sodium hydroxide, commonly called lye, is a caustic, highly reactive substance. Can dissolve several types of metal coatings, including chromium, but reacts dangerously with water and aluminum, corroding aluminum and producing flammable hydrogen gas. Thus, it can only be used with items that do not use aluminum as their main material. Follow the steps below:
- Mix 8 to 12 ounces (approximately 227 ml to 355 ml) of sodium hydroxide with 1 gallon (approximately 3.785 L) of water in a container made of a neutral material (such as a heavy-duty plastic bucket).
- Soak the chrome object in the solution until the chrome comes off. This can take quite a long time, so check the condition of your part frequently.
- Wash object thoroughly with soap and water, and rinse before drying.
Step 3. Reverse the plating process
Chromium is deposited on a metal through an electroplating process, in which an electric current is used to bind chromium to the metal at a molecular level. If you reverse this process, chrome plating can be removed very efficiently. However, this can be extremely dangerous. Not only does the process involve electrical current, but it also produces several toxic, carcinogenic chemicals as a result of the reaction. Hexavalent chromium, for example, is an extremely hazardous product. Therefore, it is better to entrust this process to professionals, the steps described below are provided for informational purposes only.
- Mix chromic acid and sulfuric acid in water, in a ratio of about 100: 1. For example, you can add 33 ounces (936 grams) of chromic acid crystals and 0.33 ounces (9.36 milliliters) of liquid sulfuric acid in distilled water to make 1 gallon (3.79 liters). Mix the solution in a suitable container used for electroplating, materials research, and / or chemical processing.
- Heat the solution. Keep the solution temperature between 35 and 46 degrees Celsius for decorative chrome and 49 to 66 for hard chrome.
- Run a negative charge from a DC power source through the electroplating solution.
- Connect the positive lead to the object to be stripped and immerse the object in the solution. The positively charged chromium will be extracted from the object.
- Rinse the object under running water. Waste must be disposed of correctly.
Method 3 of 3: Removing fake / light chrome with the right tools
Please note that no home-based process can compare to a professional solution to this problem. Since the "home" methods are compiled from various sources, hobbyists, experiments, which may be contradictory for your situation, depending on the thickness and composition of the chromium. "Home" methods are more suitable for removing fake plastic chrome plating, but may have limited effectiveness on a case-by-case basis with metallic chrome plating
Step 1. Home removal of thin and weak chromium using an abrasive
One of the easiest ways to remove chromium is with an abrasive. Mix baking soda or a solid household detergent with water to make an abrasive paste that can be rubbed into the chrome with a soft cloth until the chrome begins to give way. This method is suitable for thin chrome plating, light chrome plating, or "fake" chrome plating (eg plastic painted with fake chrome). Significant heavy-duty polishing can lead to the expected result.
Be sure to pay attention to the result, as you may scratch the base material
Step 2. Using a cooker cleaner
Certain types of chrome (especially fake plastic ones, which you may find on car models, etc.) can be removed with regular gas stove cleaners. These powerful degreasing solutions are usually sprayed in the form of a foam or spray. Apply a generous amount of cleaner (solution) to the chrome plating. Then, after 10 minutes, wipe off by scrubbing the chrome along with the cleaner (solution).
Note that some cleansing sprays can darken the base metal if not left on for too long, so you can apply the process repeatedly at short intervals until you get the desired result
Step 3. Soak the chrome part in household bleach
Another common method for removing chromium is using a bleach bath. In this case, the chrome part is completely immersed in the bleach. After about a day, depending on its thickness, the chrome should be loosened or removed completely.
- The main advantage of this method over others is that the bleach only removes the outer skin.
- After removing chromium in this way, the resulting liquid cannot be reused (for laundry, etc.), it must be disposed of.
Step 4. Use brake fluid to remove chrome plating
Conventional automotive brake fluid works as a paint thinner and also removes chrome from plastic objects. However, this method can take several days. It also requires proper handling and disposal of the brake fluid. it is highly toxic. Rub the chrome object with brake fluid and rinse after 10 minutes. Repeat the procedure if necessary to completely remove the chrome.
Note that brake fluid can dissolve plastic, so be very careful when using this method on chrome plated plastic parts (or choose another method)
Advice
Become familiar with the nature of the substrates or the metal that has been chrome plated to avoid damaging this material
Warnings
- It is very dangerous to use household chemicals, beware of contact with eyes, skin and respiratory tract; remember to wear protective gear and have a first aid kit on hand.
- Hydrochloric acid, sodium hydrochloride, sulfuric acid - are toxic, volatile and carcinogenic; Be sure to minimize risks and have special safety and first aid equipment on hand in emergencies.