Difference between revisions of "Tell Brass from Copper"
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Copper is a single metal, so every copper object has roughly the same properties. Brass, on the other hand, is an alloy of copper, zinc, and often other metals as well. The hundreds of different combinations means there is no single, foolproof way to identify all brass. That said, the color of the brass is usually distinct enough to separate it from copper. | Copper is a single metal, so every copper object has roughly the same properties. Brass, on the other hand, is an alloy of copper, zinc, and often other metals as well. The hundreds of different combinations means there is no single, foolproof way to identify all brass. That said, the color of the brass is usually distinct enough to separate it from copper. | ||
| − | [[Category:Metalworking]] | + | [[Category: Metalworking]] |
== Steps == | == Steps == | ||
===Identifying by Color=== | ===Identifying by Color=== | ||
| − | #Clean the metal if necessary. Both brass and copper develop a patina with age, usually green but sometimes other colors.<ref>http://www.minerals.net/mineral/copper.aspx</ref> If none of the original metal is visible, try [[Clean-Brass|brass cleaning techniques]]. These typically work for both metals, but to be safe you could use a commercial brass and copper cleaning product. | + | #Clean the metal if necessary. Both brass and copper develop a patina with age, usually green but sometimes other colors.<ref name="rf1">http://www.minerals.net/mineral/copper.aspx</ref> If none of the original metal is visible, try [[Clean-Brass|brass cleaning techniques]]. These typically work for both metals, but to be safe you could use a commercial brass and copper cleaning product. |
| − | #Hold the metal under white light. If the metal is highly polished, you may see false colors due to reflected light.<ref>https://play.google.com/store/books/details?id=_BtbAAAAYAAJ</ref> Look at it in sunlight or under a white fluorescent light bulb, not under a yellow incandescent bulb. | + | #Hold the metal under white light. If the metal is highly polished, you may see false colors due to reflected light.<ref name="rf2">https://play.google.com/store/books/details?id=_BtbAAAAYAAJ</ref> Look at it in sunlight or under a white fluorescent light bulb, not under a yellow incandescent bulb. |
| − | #Identify copper's reddish color. Copper is a pure metal, and always has a reddish brown appearance. A modern US penny is plated in copper (and was almost entirely copper from 1962 to 1981), so this is a good point of comparison.<ref>https://www.usmint.gov/about_the_mint/fun_facts/?action=fun_facts2</ref> | + | #Identify copper's reddish color. Copper is a pure metal, and always has a reddish brown appearance. A modern US penny is plated in copper (and was almost entirely copper from 1962 to 1981), so this is a good point of comparison.<ref name="rf3">https://www.usmint.gov/about_the_mint/fun_facts/?action=fun_facts2</ref> |
| − | #Inspect yellow brass. The word brass refers to any alloy that contains copper and zinc. Different proportions of these metals produce different colors, but the most common types of brass have a muted yellow color, or a yellow-brown appearance similar to bronze. These brass alloys are widely used in machined parts and screws.<ref>http://admin.copperalliance.eu/docs/librariesprovider5/publication-117/117-section-4-which-forms-of-brass.pdf?sfvrsn=2&sfvrsn=2</ref> | + | #Inspect yellow brass. The word brass refers to any alloy that contains copper and zinc. Different proportions of these metals produce different colors, but the most common types of brass have a muted yellow color, or a yellow-brown appearance similar to bronze. These brass alloys are widely used in machined parts and screws.<ref name="rf4">http://admin.copperalliance.eu/docs/librariesprovider5/publication-117/117-section-4-which-forms-of-brass.pdf?sfvrsn=2&sfvrsn=2</ref> |
| − | #*Some brass has a greenish-yellow appearance, but this alloy, called "gilding metal," is only used for a few specialized purposes in decoration and ammunition.<ref | + | #*Some brass has a greenish-yellow appearance, but this alloy, called "gilding metal," is only used for a few specialized purposes in decoration and ammunition.<ref name="rf2" /><ref name="rf4" /> |
| − | #Learn about red or orange brass. Many other common brass alloys can look orange or reddish brown, when they contain at least 85% copper.<ref | + | #Learn about red or orange brass. Many other common brass alloys can look orange or reddish brown, when they contain at least 85% copper.<ref name="rf2" /> These types of brass are usually found in jewelry, decorative fasteners, or plumbing.<ref name="rf4" /> Any hint or orange, yellow, or gold means the item is brass, not copper. If the brass alloy is almost entirely copper, you may need to compare it side by side with a copper pipe or item of jewelry. If you're still not sure, it's either copper or brass with such a high copper content that the distinction may not be important. |
| − | #Identify other brass. Brass with high zinc content can look bright gold, yellowish white, and even white or grey.<ref | + | #Identify other brass. Brass with high zinc content can look bright gold, yellowish white, and even white or grey.<ref name="rf2" /> These alloys are not common, since they are not machine workable, but you may find them in jewelry.<ref name="rf5">http://www.britannica.com/technology/brass-alloy#ref167378</ref> |
===Other Identification Methods=== | ===Other Identification Methods=== | ||
| − | #Strike the metal and listen to the sound. Since copper is quite soft, it should produce a muted, round sound.<ref>https://www.highettmetal.com.au/blog/copper/how-to-tell-the-difference-between-copper-and-brass</ref> A test way back in 1867 described copper's sound as "dead," while brass emitted a "clear ringing note."<ref>https://play.google.com/store/books/details?id=0_ZEAQAAMAAJ&rdid=book-0_ZEAQAAMAAJ</ref> This might be tough to judge without experience, but learning it could prove useful for an antiquing or scrap collection hobby. | + | #Strike the metal and listen to the sound. Since copper is quite soft, it should produce a muted, round sound.<ref name="rf6">https://www.highettmetal.com.au/blog/copper/how-to-tell-the-difference-between-copper-and-brass</ref> A test way back in 1867 described copper's sound as "dead," while brass emitted a "clear ringing note."<ref name="rf7">https://play.google.com/store/books/details?id=0_ZEAQAAMAAJ&rdid=book-0_ZEAQAAMAAJ</ref> This might be tough to judge without experience, but learning it could prove useful for an antiquing or scrap collection hobby. |
#*This works best for thick, solid metal objects. | #*This works best for thick, solid metal objects. | ||
#Look for stamped codes. Brass objects made for industrial purposes often have a code stamped on them to identify the exact alloy. In both the North American and European systems, the codes for brass begin with a C and are followed by several numbers. Copper is often left unlabeled, but if you want to be sure, double check the code with this quick guide: | #Look for stamped codes. Brass objects made for industrial purposes often have a code stamped on them to identify the exact alloy. In both the North American and European systems, the codes for brass begin with a C and are followed by several numbers. Copper is often left unlabeled, but if you want to be sure, double check the code with this quick guide: | ||
| − | #*The UNS system in North America uses brass labels beginning with C2, C3, or C4, or fall between C83300 and C89999. Copper, if labeled, can use codes from C10100 to C15999, and C80000–C81399.<ref>http://unscopperalloys.org/</ref> The last two digits are often dropped. | + | #*The UNS system in North America uses brass labels beginning with C2, C3, or C4, or fall between C83300 and C89999. Copper, if labeled, can use codes from C10100 to C15999, and C80000–C81399.<ref name="rf8">http://unscopperalloys.org/</ref> The last two digits are often dropped. |
| − | #*In the current European system, both copper and brass begin with C. Brass ends with the letter L, M, N, P, or R, while copper ends with A, B, C, or D.<ref>http://www.copper.org/resources/standards/euronumb.html</ref> | + | #*In the current European system, both copper and brass begin with C. Brass ends with the letter L, M, N, P, or R, while copper ends with A, B, C, or D.<ref name="rf9">http://www.copper.org/resources/standards/euronumb.html</ref> |
#*Older brass may not conform to these systems. Some older European standards (which were used quite recently) list the element symbols followed by a percentage. Anything that contains "Cu" and "Zn" is considered brass. | #*Older brass may not conform to these systems. Some older European standards (which were used quite recently) list the element symbols followed by a percentage. Anything that contains "Cu" and "Zn" is considered brass. | ||
| − | #Check how hard the metal is. This test is usually not too helpful, since brass is only slightly harder than copper.<ref>https://www.tedpella.com/company_html/hardness.htm</ref> Some types of treated copper are particularly soft, so you may be able to scratch them with a US penny (which is never true of brass).<ref>http://www2.gvsu.edu/peirsonb/hardness_testing.pdf</ref> However, in many cases there is no convenient object that will scratch one object but not the other. | + | #Check how hard the metal is. This test is usually not too helpful, since brass is only slightly harder than copper.<ref name="rf10">https://www.tedpella.com/company_html/hardness.htm</ref> Some types of treated copper are particularly soft, so you may be able to scratch them with a US penny (which is never true of brass).<ref name="rf11">http://www2.gvsu.edu/peirsonb/hardness_testing.pdf</ref> However, in many cases there is no convenient object that will scratch one object but not the other. |
#*Copper is easier to bend than brass as well, but it's difficult to draw exact conclusions from that test (especially without damaging the object). | #*Copper is easier to bend than brass as well, but it's difficult to draw exact conclusions from that test (especially without damaging the object). | ||
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== Tips == | == Tips == | ||
*Copper is a better conductor than brass, so all reddish electrical wires are copper. | *Copper is a better conductor than brass, so all reddish electrical wires are copper. | ||
*Terms such as "red brass" and "yellow brass" can have specialized meanings in different industries and regions. In this article the terms are only used to describe the color. | *Terms such as "red brass" and "yellow brass" can have specialized meanings in different industries and regions. In this article the terms are only used to describe the color. | ||
| − | *Almost all brass instruments are made from brass, not copper. The higher the copper content of the brass, the darker and warmer the sound is likely to be.<ref>http://triggertrombone.com/guide/materials/</ref> Copper is used for some wind instrument parts, but it does not seem to affect the sound for this type of instrument.<ref>http://scitation.aip.org/content/asa/journal/jasa/49/2B/10.1121/1.1912381</ref> | + | *Almost all brass instruments are made from brass, not copper. The higher the copper content of the brass, the darker and warmer the sound is likely to be.<ref name="rf12">http://triggertrombone.com/guide/materials/</ref> Copper is used for some wind instrument parts, but it does not seem to affect the sound for this type of instrument.<ref name="rf13">http://scitation.aip.org/content/asa/journal/jasa/49/2B/10.1121/1.1912381</ref> |
==Sources and Citations== | ==Sources and Citations== | ||
