Bluing gives the metal two important qualities. It gives steel products a noble black tint and at the same time provides a durable anti-corrosion coating.
It is necessary
- - container for bluing
- - protective equipment
- - metal for bluing
- - abrasive material
- - liquid for degreasing
- - copper sulfate
- - sulfuric and hydrochloric acid
- - sulphate soda
- - potash alum
- - water
Prepare a container for bluing. It is desirable that it be made of galvanized steel. If there is no steel, you can use a wooden product. Attach small metal hooks to the sides of the container. You can hang steel parts from them. Try to size the hooks so that the steel does not touch the walls during bluing.
Before steel is burnished, it must be processed. Treatment refers to the process of removing the oxide film and traces of rust. This is a very important and time consuming process. The quality of the subsequent metal coating depends on it. You can start removing the old coating using sandpaper with a sufficiently coarse grain. Then they gradually reach the zero treatment. If you are trying to do bluing at home, you can try using a drill with a wire brush for sanding. But this must be done very carefully, constantly monitoring the pressure. If you overdo it, you will have to spend twice as much time fixing the scratched surface. You can finish sanding with fine emery dust.
A well-polished part must be degreased. The fact is that an oxide film can appear only on a perfectly clean surface. Therefore, in no case should this procedure be neglected. Degrease the metal in different ways. The simplest option is to wipe the steel with acetone, gasoline or white spirit. But it is better to use the following method. Rinse the part in hot soapy water. Then immerse in a weak solution of caustic soda. It should be noted that an increase in the temperature of the solution has a positive effect on the quality of metal cleaning. The optimum temperature is 100 degrees Celsius. It is advisable to immerse the parts in the solution for 30 minutes. This time is quite enough. To complete the degreasing process, rinse the steel in water or pour over with boiling water.
Now you can burn steel. Prepare copper sulfate. It must be dissolved in water. Then you need to add a little sulfuric acid. Approximately 20 drops per liter. Now you can immerse the parts in the solution and wait until they turn red. After removing it from the solution and rinsing it in water, you need to transfer the steel to the next solution. It is made from sodium sulfate and hydrochloric acid. You need to take natra 800 grams per liter. And acids - a little less than one-eighth of a glass per liter. The solution should be heated to boiling water. Immerse metal for 30 seconds. Do not touch the parts with your hands. After that, after washing the steel elements in cold water, they are immersed in a final solution of potash alum and water. In the ratio of one liter of water to one third of a glass of alum powder. Leave the parts in this solution for at least ten hours, or even longer. The procedure is completed by rinsing and drying the product. As a result, the detail becomes black with a noble blue tint.