Is it True that Stainless Steel Cannot be Stained?

Stain Removal

Have you ever wondered if the high-end stainless steel range you just purchased can really avoid staining?
© Alan Kaplanas/Corbis

Stainless steel is a popular material found in bathroom sinks, kitchen appliances, and iconic buildings like New York’s Chrysler Building and St. Louis’ Gateway Arch. The material is known for being durable, versatile, and “stainless.” This name implies that it is resistant to stains and corrosion [source: Pistor].

Stainless steel is a type of material that is resistant to rust and unsightly blemishes due to its corrosion- and oxidation-resistant properties. The various types of stainless steel are made up of a combination of iron and at least 10.5 percent chromium (sometimes rounded up to 11 percent by engineers). When chromium is exposed to moisture and oxygen, it produces a thin oxide film that covers the product, which protects it from further damage and ensures that it always appears shiny and smooth [source: International Stainless Steel Forum].

The development of this amazing material has been attributed to various European and American metallurgists. The Germans developed an acid-resistant steel in 1908, which was used for the hull of a yacht. Two other Germans, P. Monnartz and W. Borchers, discovered that metal containing at least 10.5 percent chromium had superior resistance to corrosion. Elwood Haynes from America patented one type of stainless steel precursor in 1911, while English researcher Harry Brearley developed a similar material around the same time. After a legal battle, the two collaborated to market their products as the American Stainless Steel Company. These and other stainless metals found their way into cutlery, airplane parts, golf clubs, and other items almost immediately [source: Cobb].

However, not all stainless steel is created equal.

Different Types of Stainless Steel

Most stainless steel cookware is part of the austenitic steel group.
© Tobi Seftel/Corbis

Stainless steel is classified into four main types based on structure and composition. The most common type is austenitic, which accounts for 65 percent of all stainless steel produced. Austenitic steels can be found in products that range from cutlery and cookware to automotive trim and industrial applications. It contains at least 16 percent chromium, no more than 0.15 percent carbon, and typically includes nickel or manganese for added durability [sources: American Welding Society, Styria].

Ferritic stainless steels typically contain up to 27 percent chromium, as well as aluminum or titanium but have little or no nickel. While these materials are highly resistant to corrosion, they are less durable than their austenitic counterparts. Ferritic steels are more affordable than austenitic varieties and are commonly used in mufflers, exhaust systems, kitchen counters, and sinks [sources: American Welding Society, Styria].

Martensitic stainless steels are not as corrosion-resistant as austenitic and ferritic varieties but are known for their extreme strength and durability. The material contains 12 to 14 percent chromium, along with small amounts of molybdenum (0.2 to 1 percent) and carbon (0.1 to 1 percent). These steels also contain little or no nickel (less than 2 percent). Martensitic stainless steels are magnetic and are often used in products where this feature is useful, like a kitchen backsplash to which a spice rack or other metal object can be attached without using fasteners [sources: American Welding Society, Styria].

Duplex stainless steels are a combination of austenite and ferrite that provide improved corrosion resistance, strength, and durability. The mixture of half austenitic and half ferritic materials results in a steel with more chromium and less nickel than pure austenitic steels. These steels are commonly used in chemical plants and piping applications. Despite its durability, stainless steel is not completely stain-proof. The protective layer of film can break down over time, leading to corrosion and pitting. The level of rust resistance depends on the materials used to create the steel, with more chromium providing greater corrosion protection. It is important to note that many advertised stainless steel products are actually plated and susceptible to damage if scratched, and buyers should clarify the materials used. To clean stainless steel appliances and products, soap and water are usually sufficient, with tougher stains requiring household remedies like olive oil or vinegar. Some products are tagged with numbers indicating their proportions of chromium and nickel, with higher percentages providing greater protection against corrosion.

Additional Information

Author’s Note: Can Stainless Steel Really Resist Stains?

Stainless steel is a material that has been labeled as “stainless” just like my pants have been labeled as “wrinkle-free.” Although my pants have a “no-iron” tag, there are different opinions on when wrinkles should be removed. I have worn the pants straight out of the dryer and ended up looking like I slept under a dumpster. Thus, truth in advertising is questionable.

Related HowStuffWorks Articles

• Is stainless steel becoming obsolete?
• How to Eliminate Iron and Rust Stains
• How Iron and Steel Function
• Top 10 Eco-friendly Countertops
• Top 5 Materials Used in Car Manufacturing

Sources

• American Welding Society. “Types of Stainless Steel.” (June 23, 2013) http://www.aws.org/w/a/wj/1998/11/kotecki
• British Stainless Steel Association. “The Discovery of Stainless Steel.” (June 23, 2013) http://www.bssa.org.uk/about_stainless_steel.php?id=31
• British Stainless Steel Association. “The History of Stainless Steel.” (June 23, 2013) http://www.bssa.org.uk/about_stainless_steel.php?id=82
• Cobb, Harold. “The History of Stainless Steel.” ASM International. 2010. http://books.google.com/books?id=E30rCBeM8nkC&source=gbs_navlinks_s
• Dynamic Fabrication Inc. “Precipitation Hardening Stainless Steel.” (June 27, 2013) http://stainlesssteel-fabrication.com/precipitation_hardening_stainless_steel.asp
• International Stainless Steel Forum. “The Stainless Steel Family.” (June 23, 2013) http://www.worldstainless.org/Files/issf/non-image-files/PDF/TheStainlessSteelFamily.pdf
• Pistor, Nicholas. “Gateway Arch showing rust and decay.” St. Louis Post-Dispatch. Aug. 22, 2010. (June 23, 2013) http://www.stltoday.com/news/local/metro/gateway-arch-showing-rust-and-decay/article_75095ba4-2d7d-5811-b4f9-a7ce769ddb0d.html
• Qiu, Jianhai. “Stainless Steels and Alloys: Why They Resist Corrosion and How They Fail.” WebCorr Corrosion Consulting Services. (June 23, 2013) http://www.corrosionclinic.com/corrosion_resources/stainless_steels_why_how_p1.htm
• Stainless Online. “Ask Dr. Steel: ‘How Do You Clean Stainless Steel?’” (June 23, 2013) http://www.stainless-online.com/cleaning-stainless.htm
• Stainless Online. “Ask Dr. Steel: ‘What is Stainless Steel Stainless?’” (June 23, 2013) http://www.stainless-online.com/stainless-steel.htm
• Styria. “Stainless Steel Applications in Minerals and Industry.” (June 23, 2013) http://www.sassda.co.za/events/icda%20conference/Styria%20ICDA.pdf

FAQ

1. Is it true that stainless steel can never be stained?

No, stainless steel can still be stained, it just has a higher resistance to it than other materials. The chromium oxide layer on the surface of stainless steel is what makes it resistant to staining, but it can still be damaged by harsh chemicals or abrasive materials.

2. What are the common causes of staining on stainless steel?

Stainless steel can be stained by exposure to high heat, abrasion, or contact with harsh chemicals like bleach or ammonia. Water spots, fingerprints, and oil stains can also leave marks on stainless steel surfaces.

3. Can scratches on stainless steel cause staining?

Scratches on stainless steel can provide a breeding ground for rust or corrosion, which can then lead to staining. It’s important to clean and maintain stainless steel surfaces to prevent scratches and keep them in good condition.

4. How can I prevent staining on stainless steel?

To prevent staining on stainless steel, avoid contact with harsh chemicals and abrasive materials. Clean stainless steel surfaces regularly with a soft cloth and mild detergent, and dry them thoroughly to prevent water spots. You can also use a stainless steel cleaner or polish to maintain the surface.

5. What is the best way to clean stained stainless steel?

If your stainless steel has become stained, start by cleaning it with a mild detergent and warm water. For tougher stains, you can try using a stainless steel cleaner or polish. Always follow the manufacturer’s instructions and test the product on a small, inconspicuous area first.

6. Can acidic foods or liquids stain stainless steel?

Acidic foods or liquids like citrus juice or vinegar can cause discoloration or etching on stainless steel if left in contact for too long. To prevent this, clean up spills and stains immediately and avoid leaving acidic substances on stainless steel surfaces for extended periods of time.

7. Can stainless steel rust or corrode?

Despite its name, stainless steel can still rust or corrode if exposed to harsh environments or chemicals. Regular cleaning and maintenance can help prevent rust and corrosion, but it’s important to choose the right grade of stainless steel for your intended use.

8. Is there a difference between “stainless” and “stain-resistant” steel?

Stainless steel is a type of steel that contains chromium, which creates a thin layer of chromium oxide on the surface that helps resist staining and corrosion. “Stain-resistant” steel may not contain enough chromium to create this protective layer, and may be more susceptible to staining.

9. Can stainless steel cookware become stained?

Stainless steel cookware can become discolored or stained over time, especially if it’s exposed to high heat or abrasive cleaning methods. To prevent staining, avoid using metal utensils or harsh cleaning products, and clean your cookware thoroughly after each use.

10. How long does stainless steel typically last before staining or corroding?

The lifespan of stainless steel depends on a variety of factors, including the grade of steel, the environment it’s used in, and how well it’s maintained. In general, high-quality stainless steel can last for many years without staining or corroding if it’s properly cared for.