Metal polishing is used to improve the cleanliness of the surface of devices and parts, to eliminate various traces of previous processing on them (scratches, strokes, the smallest irregularities and small dents). There are two types of polishing: preliminary and final. Pre-polishing is used to mechanically remove surface irregularities with loose abrasives. The final polishing is done with fine grinding powders.
Metal products can be polished using special polishing pastes, which include chalk, lime, tripoli, dolomite, chromium oxide, aluminum oxide and iron oxide.
At the same time, the surfaces of the finest finishing are reached by friction with a piece of woolen cloth or felt, smeared with a special paste. After polishing, such a surface will acquire a mirror-like shine.
To prepare a paste for polishing metals, take 20 g of paraffin, 10 g of stearin, 3 g of industrial fat and M 50 - 67 g micropowder. Mix all the ingredients until a homogeneous consistency is obtained.
Metals can also be polished chemically, that is, by simply immersing the object in a bath with a special polishing solution without using an electric current. For this, you can use porcelain trays or glasses.
To prepare such a polishing solution, take: 350 ml of concentrated phosphoric acid, 50 ml of concentrated nitric acid, 100 ml of concentrated sulfuric acid and 0.5 g of copper sulfate or nitrate. Mix everything.
The working temperature of the bath should be 100-110 ° C. In time, it is necessary to polish from 0.5 to 4 minutes. Polishing will produce suffocating fumes, so place the bath in a fume hood or outdoors.
If you need to polish some inaccessible metal surfaces, especially on small jewelry, then polish with wood chopsticks (linden, birch, aspen). Cut the sticks in such a shape that fits the surfaces to be treated with a cylindrical, rectangular, triangular section, with a concave and convex working part. Rub this part of the stick with the prepared pasta.
For polishing large metal surfaces, you can use wooden pads of various shapes, pre-glued with leather on the outside with the inner side.