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https://www.wikihow.it/Distinguere-l%27Ottone-dal-Rame
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Copper is a pure metal, so every object made with this material has more or less similar properties;brass is instead an alloy of copper, zinc and often other metals.The hundreds of different combinations make it impossible to develop a single, foolproof method for recognizing all brass.That said, the color of this alloy is generally distinctive enough to distinguish it from copper.
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Clean the metal if necessary. Both copper and brass, over time, develop a patina which is usually green, but can take on other shades.[1] If you can't see any portion of the original metal, try one of the techniques described in this article, which are generally effective for both materials;To avoid risks, you can however use a commercial product specific for copper and brass.
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Hold the metal under a white light. If the surface is very shiny, you may see false colors due to reflected light.[2] Observe it in sunlight or near a white fluorescent light bulb, not a yellow incandescent one.
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Recognize the reddish color of copper. It is a pure metal that always has a red-brown color.The 1, 2 and 5 euro cent coins are copper plated, so they can become a good comparison reference.[3]
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Inspect the yellow brass. The term brass refers to an alloy that contains copper and zinc and its final color varies based on the proportion of the two metals.However, in most cases brass has a pale yellow or yellow-brown color similar to bronze.Brass alloys are widely used to make screws and mechanical parts.[4]
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Find out about red or orange brass. Many other common alloys take on an orange or reddish-brown hue because they contain at least 85% copper;[7] they are used in the production of jewelry, decorative buckles or in piping.[8] Any hint of orange, yellow or gold indicates that the material is brass and not copper.If the alloy is almost entirely copper, you should visually compare the object to a pure copper tube or a piece of costume jewelry.If you still have doubts, it could be either copper or brass with such a high percentage of copper that any distinction is useless.
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Recognize other types of brass. Those that contain a lot of zinc have a bright golden color, a yellowish-white hue and even white or gray.[9] These are uncommon alloys, as they cannot be machined, but you can encounter them in jewelry items.[10]Advertising
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Strike the metal and listen to the sound it makes. Since copper is quite soft, it produces a dull, round sound.[11] An old test conducted in 1867 defined the sound emitted by copper as "dead", while that of brass is "a clear ringing note".[12] It's not easy to judge the difference if you don't have experience, but learning this method could be useful for people with antiques or collecting as a hobby.
- This method works best with thick solid metal objects.
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Look for engraved marks. Brass objects made for industrial purposes often have an engraved or printed code, which allows the exact composition of the alloy to be identified.The coding criteria for brass are the same for both North America and Europe and include an acronym with the letter C followed by several numbers.Copper rarely has any identifying marks, but if you want to be sure, compare the brand you read on the object with those in this short list:
- The UNS system in force in North America uses codes that begin with C2, C3 or C4 or that fall in the range between C83300 and C89999.Copper, if marked, bears codes between C10100 and C15999 or between C80000 and C81399,[13] although the last two digits are often omitted.
- The current European system provides a code starting with "C" for both copper and brass;however, alloy marks end in the letters L, M, N, P, and R, while copper marks end in A, B, C, or D.[14]
- Antique brass items may not have these codings.Some old European standards (sometimes still in use) require the use of the chemical symbol of each element followed by the percentage.Anything containing "Cu" (copper) and "Zn" (zinc) is considered brass.
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Check the hardness of the material. This test is generally not very useful, as brass is only slightly harder than copper.[15] Some types of treated copper are particularly malleable, so you are able to scratch them with a coin (which is impossible to do with any brass alloy).[16] However, in many cases it is not possible to have an object that is capable of scratching one material but not the other.
- Copper bends more easily than brass, but it is difficult to draw exact conclusions from this test (especially without damaging the object).
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- Copper is a better conductor than brass, reddish electrical wires are therefore made of copper.
- In some cases, the terms "red brass" and "yellow brass" used in the metal industry indicate a specific material, but in this article they have been used only to describe colors.
- Almost all musical instruments defined as "brass" are made of brass and not copper.The higher the copper content in the alloy, the warmer and deeper the sound emitted by the instrument.[17] Copper is used for some components of wind instruments, but does not appear to affect the sound.[18]
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