Advice 1: How to identify bronze

Modern industry knows a variety of complex metal alloys, but, perhaps, the oldest and most common – bronze: an alloy of copper with tin, beryllium, chromium, aluminium. This alloy is used not only in production but also arts and crafts. The master is made from malleable bronze figurines, jewelry, coinage.
How to identify bronze
To determine the bronze, then to know the composition of the alloy that you have in your hands. For those who work with bronze, rather superficial inspection. Clean the item from dust and corrosive oxides. Then go to the usual inspection or binocular magnifying glass, but pick the proper lighting. Make a test macroscopic mechanical clearing with a scalpel or sharp knife.

Already by the color of the slice, you can determine what, before you alloy. Depending on the composition of the bronze has a different color. If the bronze contains 90% copper, it is red if copper 85% the alloy becomes yellow if 50% are white, 35% are steel gray.

Alloys of copper with beryllium bright red, and aluminium – have pastel shade and sometimes stringy inclusions.


For a more precise analysis, conduct a chemical examination with the reagents. Place 0.05 g of the alloy in the form of sawdust or shavings into the beaker, add 10 ml of nitric acid, which was pre-dilute with water in 1:1 ratio, cover the beaker glass. After dissolve a greater quantity of alloy, heat liquid in a water bath nearly to boiling and soak it hot for 30 minutes. If after this experience at the bottom of the beaker will appear a white precipitate, so the product is made of bronze.
In an industrial environment, use the spectrometer. This device is based on the existing parameters of the physical properties of metal and its particle (e.g., scraping), is conducting a study into its components.

In laboratory conditions it is possible to analyze the photometric method, based on the interaction of lead diethyldithiocarbamate in chloroform with copper ions in an acidic medium, resulting in the diethyldithiocarbamate copper. The uninitiated can understand the reaction to change the color of the liquid in the test tube with the test material in the presence of the bronze alloy content is painted in yellow-brown color.

Advice 2: How to clean bronze

Bronze candlesticks and statues give the interior a unique and special flavor 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 blue-green oxide coating. This is especially true of things that were stored in basements or attics. Bronze can be cleaned to give them the original appearance.
How to clean bronze
You will need
  • -sulfuric acid;
  • -potassium dichromate;
  • -ammonia;
  • -acetic acid;
  • water;
  • -sawdust;
  • -soda ash;
  • protection sunglasses;
  • -glassware;
  • -rubber gloves;
  • woolen cloth;
  • wax or paraffin.
If bronze is not oxidized too much and need to clear only the individual spots on the surface, apply the following method. Clean the item by washing in a warm solution of soda ash. Rinse it with water.
Make a mess of acetic acid and sawdust. When the sawdust will swell, the resulting mass wipe the bronze item using wool cloth. Acetic acid when this corrodes the oxides and sawdust Polish the product. After processing the thing rinse with cold water and wipe.
In case of strong contamination by oxides of the surface of the subject, prepare the following composition. To 1 liter of water take 10 g of potassium dichromate and 20 ml of concentrated sulfuric acid. Pour the solution into a glass vessel up to the top (including the volume of the object). The course will dip into a solution and observe the process of dissolution of oxides.
As soon as the areas of clean metal surfaces, immediately remove the object and place it into the solution of ammonia to neutralize the acid. Then wash the product with water and wipe and dry. Process with sulfuric acid and potassium dichromate requires care and skill not to damage the metal.
After cleaning the bronze, its surface is preferably waxed. This can be done using wax and cloth or alcohol solution of the wax or paraffin. This treatment will protect the object surface from oxidation.
You need to remember the rules of working with acid. In particular, in the preparation of solutions is necessary to pour acid into water, not Vice versa.

A solution of sulfuric acid and potassium dichromate is a very caustic and corrosive substance. Pour it in glass vessels. At work you have to use gloves and safety glasses.
Useful advice
Dichromate potassium can you buy in stores chemicals. Sulfuric acid is in the automobile.

Advice 3: How to distinguish brass from bronze

To distinguish bronze from brass and, moreover, to determine the exact composition of the alloy is possible only in special laboratories (e.g., methods, spectroscopic analysis). Unfortunately, at home (especially when it is impossible to cause scratches or otherwise damage the object) the range of possibilities will be quite limited. However, there is an algorithm that gives even an approximate, but still results.
How to distinguish brass from bronze
You will need
  • Accurate scales and a transparent graduated container with water; a calculator; a strong magnifier or a microscope, samples of bronze and brass chipped.
Start with visual analysis. You must thoroughly clean the item and place into the sunlight. As a rule, the darker bronze of brass, and, if you evaluate the color, the bronze goes into the "red" spectrum (i.e. from reddish to brown) and brass in yellow up to white. However, this method is extremely inaccurate, so proceed to the next step.
Analyze the alloy density. You will need accurate scales and a transparent, graduated container with water. Lowering of the object in water is determined by its volume, weighing a lot. Density is the ratio of body mass to its volume, and transfer format C (kg/ cubic meter). Typically, bronze is denser than brass, and the dividing line lies at the value of 8700 kg/cu. m. 8400 – 8700 kg/cubic meter – almost certainly brass. 8750 – 8900 – almost certainly bronze.
Finally, the structure of the alloy. It should be noted that what is needed are samples of items which can be uniquely identified as bronze and brass; the samples must be chipped.
For the actual analysis will need a strong (preferably binocular) microscope or magnifying glass (even children). The analysis is placed in view at the same time sample (cleavage) and the object of analysis. What we should look for? On the structure of the alloy – as they say, his "grain". Generally, bronze is larger and more coarse grain than the brass.
Bronze and brass are alloys based on copper (about 90%).
Typically, the main alloying element in bronze is tin, for brass – zinc. This is in principle true for the alloys made before the beginning of the 1980s (that is, the task was limited to the identification of zinc in the alloy). Later, however, the zinc began to enter into the composition of bronze, so the measurement is now based on complicated methods of determining the percentage of elements in the alloy, which is practically impossible at home.
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