How to clean bronze
Bronze candlesticks and figurines give the interior a uniqueness and a special aroma of antiquity. They can be extremely beautiful, but they have one drawback. Bronze objects under the influence of moisture and air, as well as other adverse factors, are covered with a blue-green coating of oxides. This is especially true for things that were stored in basements or attics. Bronze items can be cleaned to restore their original look.
You will need
- -sulfuric acid;
- -potassium dichromate;
- -acetic acid;
- - sawdust;
- - soda ash;
- -protective glasses;
- -rubber gloves;
- - woolen rag;
- - wax or paraffin.
If the bronze has not oxidized too much and only a few spots on the surface need to be cleaned, use the following method. Degrease the item by rinsing it in a warm soda ash solution. Rinse with water.
Make a porridge with acetic acid and sawdust. When the sawdust swells, wipe the bronze object with the resulting mass with a woolen rag. At the same time, acetic acid corrodes oxides, and sawdust polishes the product. At the end of the treatment, rinse the item with cold water and dry thoroughly.
In case of severe contamination of the surface of the object with oxides, prepare the following composition. For 1 liter of water, take 10 g of potassium dichromate and 20 ml of concentrated sulfuric acid. Pour the solution into a glass vessel not to the top (taking into account the volume of the object). Dip the object into the solution and observe the process of dissolution of oxides.
As soon as areas of a clean metal surface appear, immediately remove the object and place it in a solution of ammonia to neutralize the acid. After that, rinse the product with water and dry it thoroughly. The process with sulfuric acid and potassium dichromate requires some care and skill in order not to damage the metal.
After cleaning the bronze, it is desirable to wax its surface. This can be done with wax and a cloth, or with an alcohol solution of wax or paraffin. This treatment will protect the surface of the object from oxidation.
You need to remember the rules for working with acid. In particular, when preparing solutions, it is necessary to pour acid into water, and not vice versa.
A solution of sulfuric acid and potassium dichromate is a very caustic and aggressive substance. It can only be poured into glass vessels. Be sure to wear gloves and goggles when working.
Potassium dichromate can be purchased at chemical stores. Sulfuric acid is also supplied in car dealerships.