Burnishing, or oxidation, became known a long time ago. Previously, this treatment was used to protect metal from corrosion, but now - mainly for decorative purposes. It is not difficult for a craftsman to carry out a burnishing at home in order to give the metal product an interesting look or to restore a hunting rifle. For this you need only desire and certain knowledge.
Ways to make burnishing at home have become
The simplest of them is coating the metal with oil and subsequent heating. This is done as follows. The workpiece is cleaned and degreased, then rubbed with a thin layer of drying oil (can be with vegetable oil). Then it is placed in a heating cabinet or an ordinary oven and heated to four hundred degrees. The result is a strong decorative film of a dark brown hue.
Another way to perform burnishing at home is to cook metal billets in a strong solution of alkali (potassium, sodium hydroxide). In this case, the metal acquires a beautiful blue tint, but the bluing is not very pronounced - light. Therefore, this method is more suitable for small cylindrical metal objects. To obtain a more pronounced blue-black shade, the workpiece must be boiled in a solution consisting of 1 liter of water, a quarter kilogram of sodium nitrite, 700 grams of sodium hydroxide and 200 grams of sodium nitrate.
The most difficult way to make burnishing at home, but also giving the best results, is the digestion of the workpiece in a molten sodium nitrate. The process should occur at a temperature of 350 degrees Celsius. In this way, you can get a very strong, beautiful bluish tint oxide film.
Gun barrel bluing
All the methods described above to make burnishing at home are of little use in order to restore gun barrels. For such work, there is a special composition that can be purchased in specialized stores. In the event that such a tool is not available in affordable stores or for some reason its use is undesirable, the following is a good way to carry out the bluing of trunks at home.
A stainless steel pipe of suitable diameter and length is used as a container. One end of the pipe is welded.
1. Trunks with abrasive materials are cleaned from rust and old burnishing, and then polished with a felt circle.
2. At both ends, the trunks are closed with chemical resistant plugs. The surface of the workpiece is degreased in two stages. First, it is simply wiped with gasoline, and then the trunks are immersed for twenty minutes in a solution heated to 70 degrees. The composition of the solution is as follows: one liter of water, 50 g of sodium hydroxide, thirty grams of soda ash, the same amount of sodium phosphate and 5 grams of silicate glue.
3. To remove the old oxide film, decapitation or weak etching is used. The barrel is dipped in a five percent solution of sulfuric acid and aged there for one minute.
4. The main process occurs using an aqueous solution of phosphoric acid (0.7 / 100), ammonium chloride (6/100), sodium hyposulfite (8/100) and nitric acid (0.3 / 100). The trunks are “boiled” at a temperature of 70 degrees. In one hour.
5. To fix the obtained oxide film, the billet is immersed for five minutes in a solution of chrompeak (120 g per liter of water). The temperature of the solution is 70 degrees.
After the procedure, metal burnishing at home ends with a thorough washing of the trunks, and in no case should they be taken with bare hands. Particular attention should be paid to safety measures with each processing method! All substances are very aggressive!