How to chrome metal

Content

Steps
Method 1 of 4: Using chrome for decorative purposes
Method 2 of 4: Use a hard chrome plating for large parts
Method 3 of 4: Hexavalent Chromium Solution
Method 4 of 4: Electrolysis System
Tips
Warnings
What do you need

The chromium plating process consists in obtaining by an electrolytic method a thin surface layer of chromium on a part, usually made of metal with low corrosion resistance. Chromium is a fairly common metal, which, however, is almost never used in its pure form. You won't find items made from chrome, however chrome plating is widespread. This process makes it possible to obtain very bright, glossy, mirror-like metal surfaces of parts of cars and motorcycles, plumbing fixtures, and many other household and industrial objects. With its high resistance to oxidation, chromium protects metals and reduces surface friction. Chromium plating is a highly specialized process using highly toxic, volatile and carcinogenic substances (such as chromic and sulfuric acids), with very harmful production wastes. If you are interested in this process, be sure to follow all safety measures.

Steps

Method 1 of 4: Using chrome for decorative purposes

1 Chromium can be applied decoratively to corrosive metals such as steel, brass, copper, aluminum, stainless steel.
- Chromium reflects light well, has a more aesthetic and smoother appearance compared to other coatings such as paint.
- In decorative electrolytic chrome plating, nickel and chrome are applied to a metal object such as a wheel rim or a car bonnet.
- Nickel provides a smooth, shiny surface and improves corrosion resistance.
- A very thin layer of chromium on top of the nickel protects it from tarnishing, scratching and rusting.

Method 2 of 4: Use a hard chrome plating for large parts

1 Hard chrome plating, also known as industrial or engineering chrome, is used on stressed parts (eg steel) of large machinery to reduce friction and wear.
- The hard chrome plating is not harder than other chrome plating, it is simply thick enough to measure its hardness.
- Hard chrome coatings are three orders of magnitude thicker than decorative coatings.

Method 3 of 4: Hexavalent Chromium Solution

1 To make 3.79 liters (1 gallon) of solution, mix 936 grams (33 ounces) of chromic acid and 9.36 grams (0.33 ounces) of distilled water.
- The proportions may be slightly different, depending on the area of the chrome-plated surface.
2 Stir the solution in the immersion bath used for experiments or chemical treatments.
- Degrease and clean parts thoroughly before coating.
- When preparing the solution, add the ingredients carefully, avoiding splashing.
- Remember that the solution is carcinogenic.
- Be extremely careful, as the solution is prone to fire and can also interact with many other substances, which is unsafe.

Method 4 of 4: Electrolysis System

1 Dissolve nickel plates in chromic / sulfuric acid.
2 Connect the positive pole of the power source to the solution.
3 Connect the negative pole to the part and immerse it in the solution.
- A negatively charged part will attract positively charged metal ions to itself.
- The thickness of the coating is determined by the duration of the electrolysis process.
- Maintain the temperature of the solution between 35-46 degrees Celsius (95-115 degrees Fahrenheit) for a decorative finish.
- For hard chrome plating, keep the solution temperature between 49-66 degrees Celsius (120-150 degrees Fahrenheit).
- When working with reagents, be sure to use a respirator and other protective equipment.
4 After coating, rinse the part under running water several times.

Tips

To obtain a uniform coating, preheat the part to the solution temperature before submerging it in the bath.
Chromic acid is highly corrosive, however it can be stored in a tightly closed glass container and filtered before next use.

Warnings

The rules for the disposal of acid solutions are strictly regulated by law; follow the local regulations.
When working with acids, be sure to use protective equipment such as goggles, an apron, a respirator mask, heavy rubber gloves.
Chromic and sulfuric acid enter into dangerous reactions with acetone, alcohols, sodium, potassium, ammonia, arsenic, hydrogen sulfides, phosphorus, pyridine, selenium, sulfur and many other substances.
Avoid any contact of acids with skin.
Before starting work, stock up on a first-aid kit that is easily accessible to all participants in the experiment.
Chromic acid solution reacts quickly with many materials, including common fuels, which can cause fires and fires.
Avoid breathing any vapor.
Remember that chromic acid solution is a carcinogen.