Copper is a single metal. So, all objects of copper have more or less the same properties. On the other hand, brass is an alloy of copper, zinc, and sometimes other metals as well. With hundreds of different combinations, there is no one sure way to detect all brass. However, the color of brass alone is usually clear enough to distinguish it from copper.
Step
Method 1 of 2: Identifying By Color
Step 1. Clean the metal first if necessary
Both copper and brass will eventually form a patina which is usually green, but may also be other colors. If the metal's original color isn't showing, try a brass cleaning technique. The technique is usually used successfully on both types of metal. However, to be on the safe side you can use commercial brass and copper cleaning products.
Step 2. Put the metal under a white light
If the metal is really shiny, you may see false colors due to reflected light. Notice the metallic color under the white fluorescent light bulb, but not under the yellow incandescent bulb.
Step 3. Notice the reddish color of the copper
Copper is a pure metal and always has a reddish-brown color. Modern US coins are minted with copper (and were made almost entirely of copper from 1962 to 1981). So, if you have or have seen such coins, you can use them for comparison.
Step 4. Observe the yellow color on the brass
Brass is a mixture of copper and zinc. However, in different ratios, the combination of these two metals will produce different colors. However, brass is usually a dark yellow or yellow-brown color similar to bronze. This brass alloy is widely used in engine parts and screws.
Some types of brass have a greenish-yellow color. However, this alloy is referred to as "gilding metal" and is only used in decorations or special ammunition
Step 5. Identify red or yellow brass
There are many other types of brass that appear orange or fawn if they contain at least 85% copper. This type of brass is usually found in jewelry, decorative bolts, and plumbing. A tinge of orange, yellow, or gold indicates that the metal is brass, and not copper. If the brass alloy consists almost entirely of copper, you will need to compare it directly to copper pipes or jewelry. If you're still not sure, the metal should be copper or brass with a copper content so high that the difference no longer matters.
Step 6. Identify other types of brass
Brass with a high zinc content will appear bright gold, yellowish-white, and even white or gray. This metal alloy is not commonly found because it cannot be used in machines. However, you may find it in jewelry.
Method 2 of 2: Other Ways
Step 1. Hit the metal and hear the sound
Since the copper texture is quite soft, the resulting sound should be muffled and full. Tests in 1867 described the copper sound as a "dead" sound, while the brass sound as a "clear tinkling" sound. These two sounds can be difficult to tell apart if you are not experienced. However, you will benefit from learning it if your hobby is collecting antiques or collecting metal scraps.
This method works best on thick, solid metal objects
Step 2. Find the stamp code
Brass objects made for industry are often stamped. This stamp code serves to detect the mixture with certainty. In both the North American and European systems, the code for brass begins with the letter C and is followed by a number of numbers. Copper is often unmarked. However, if you want to be sure, check the code with this guide:
- The UNS system in North America uses labels starting with C2, C3, or C4 for brass, or between C83300 and C89999. If marked, copper can use codes between C10100 to C15999, and C80000–C81399. The last two numbers are often not written down.
- In the current European system, both copper and brass codes begin with the letter C. The codes for brass end in the letter L, M, N, P, or R, while the codes for copper end in the letter A, B, C, or D.
- Old brass objects may not follow this system. Some old European standards (used until recently) included the symbol for the metal element followed by the percentage. All objects containing "Cu" and "Zn" are considered brass.
Step 3. Check the hardness of the metal
This test is usually not very useful because brass is only slightly harder than copper. Some types of copper that have been processed will be so soft that they can be scratched with US coins (which is not the case with brass). It's just that, in most cases, nothing can scratch any of the metals, but neither the other metal at the same time is easy to find for this test.
Copper is also easier to bend than brass. However, drawing conclusions from those tests alone would be difficult (especially without damaging objects)
Tips
- Copper is a better conductor than brass. That's why all reddish-colored electrical wires are made of copper.
- Terms such as "red brass" and "yellow brass" can have specific meanings in different industries and regions. In this article, both terms are used only to describe the color.
- Almost all brass instruments (brass instruments) are made of brass, not copper. The higher the copper content in the brass, the darker the color of the tool and the warmer the sound will be. Copper is used in some parts of wind instruments, but does not affect the sound.
