So many products we use in and around our homes are made from stainless steel. From bowls, to water bottles, to cutlery, to appliances, stainless steel takes up a lot of real estate.
But how much do we actually know about stainless steel?
My guess is, that since you are reading this article, not as much as you would like. You want to know more about food grade stainless steel. You want to be informed about the materials used in your home.
In this article, I explain the differences between various types of stainless steels.
As well, I scoured the internet and answered questions that are commonly asked about food grade stainless steel.
So grab a coffee, sit back, and get prepared to know everything you will ever need about food grade stainless steel.
What is stainless steel?
The key element that classifies steel as stainless is that the iron alloy (mix of several metals) is comprised from a minimum of 10.5% chromium.
The main requirement for stainless steels is that they should be corrosion resistant for a specified application or environment.
Alloying elements are added to enhance their structure and properties such as formability, strength, and toughness.
These may include:
- Chromium
- increases resistance to oxidation
- the higher the percentage, the higher increase in corrosion resistance
- Nickel
- the essential element in the 300 series of stainless steel
- provides strength and toughness
- makes material non-magnetic
- Molybdenum
- adds resistance to pitting of stainless steel due to chlorides
- Titanium
- used to stabilize stainless steel in the manufacturing process
- Copper
- added to austenitic stainless steel containing molybdenum
- improves corrosion resistance to sulfuric acid
- Carbon
- always present in stainless steel
- levels are low in all types of stainless steel except martensitic
- higher levels in martensitic provide strength and hardness
- Nitrogen
- increases resistance to pitting
- Silicon
- added to stainless steels containing molybdenum
- improves corrosion resistance to sulfuric acid
- improves resistance to oxidation
- Manganese
- replaces some of the nickel in the 200 series stainless steels
- assists in de-oxidation during the manufacturing process
The selection of a particular “type” and “grade” of stainless steel must meet the corrosion resistance requirements.
There are three types of stainless steel:
- austenitic
- ferritic
- martensitic
What is food grade stainless steel?
While there is no official classification of ‘food grade’ stainless steel, the 316 grades are commonly referred to as food grade stainless steel.
There are other grades of stainless steel that are also suitable for food processing and handling such as the 200 series, 304 and 430 types.
Stainless steel grades 200’s, 304 and 316 are considered austenitic stainless steels whereas 430 grade is considered a ferritic stainless steel.
What are Austenitic stainless steels?
Austenitic are the most common types of stainless steels.
Austenitic steels are non-magnetic stainless steels that contain high levels of chromium, nickel and low levels of carbon.
They are known for their formability and resistance to corrosion.
Nickel-based austenitic steels are classified as 300 series. The most common grade is 304, which consists of 18% chromium and 8% nickel. Also known as 18/8 stainless steel.
Eight percent is the minimum amount of nickel that can be added to a stainless steel containing 18% chromium in order to completely convert all the iron alloy to austenite.
Molybdenum can also be added to a level of about 2% for grade 316 to improve corrosion resistance.
Austenitic steels are non-magnetic in the annealed condition, although they can become slightly magnetic when cold worked (the process of strengthening a metal by changing its shape without the use of heat). They have good formability and weldability, as well as excellent toughness, particularly at low or cryogenic temperatures.
Austenitic grades also have a low yield stress and relatively high tensile strength.
While austenitic steels are more expensive than ferritic stainless steels, they are generally more durable and corrosion resistant.
food grade stainless steel 200 grade
These grades of stainless steel have low nickel content. They are referred to as chrome-manganese stainless steels.
Properties
- corrosion resistant, although less resistant to pitting than 300 series
- tough – harder and stronger than 300 series
- cheaper because of low nickel content
Applications
- dishwashers
- cutlery
- cookware
- food and beverage equipment
Stainless steel grade 304
304 stainless steel is the most common form of stainless steel used around the world, largely due to its excellent corrosion resistance and value.
Properties
It contains between 16 and 24% chromium and up to 35% nickel, as well as small amounts of carbon, silicon, and manganese. The remainder of the chemical composition is primarily iron.
Because of the high percentage of chromium contained in 304 grade stainless steel, 304 can withstand corrosion from most oxidizing acids.
That durability makes 304 easy to sanitize, and therefore ideal for kitchen and food applications.
304 stainless steel does have one weakness: it is susceptible to corrosion from chloride solutions, or from saline environments like coastal regions.
Chloride ions can create localized areas of corrosion, called “pitting,” which can spread beneath protective chromium barriers to compromise internal structures.
The high amounts of chromium and nickel give 304 stainless steel excellent corrosion resistance (except against chloride).
Applications
Common applications of 304 stainless steel include:
- Appliances such as refrigerators and dishwashers
- Commercial food processing equipment
- Fasteners
- Piping
- Heat exchangers
- Structures in environments that would corrode standard carbon steel
Stainless Steel Grade 316
Grade 316 is the most common grade of stainless steel. It is also known as 18/10 stainless steel.
Properties
Grade 316 stainless steel is an austenitic chromium-nickel stainless steel that contains between 2-3% molybdenum.
The molybdenum content:
- increases corrosion resistance
- improves resistance to pitting in chloride ion solutions
- increases strength at high temperatures
Applications
Grade 316 stainless steel is used when increased corrosion resistance is needed, such as:
- food processing
- commercial kitchens
- chemical processing
- water treatment
- swimming pool fittings
- laboratory equipment
Stainless Steel Grade 304 VS 316
Grades 304 and 316 sound pretty similar, but there are some notable differences between the two.
Grade 304
- 18% chromium
- 8% nickel
- 0% molybdenum
- NOT chlorine resistant
- corrosion resistant
Grade 316
- 18% chromium
- 10% nickel
- 2% molybdenum
- IS chlorine resistant
- superior corrosion resistance
Well, it comes down to two factors:
- cost
- corrosion resistance requirements
If you don’t need the added resistance of 316, standard 304 grades will provide similar performance and longevity at a lower price point.
As a consumer purchasing a product, chances are you will not know what grade of stainless steel you are purchasing. Products are generally unmarked. You have to trust that the manufacturer picked the most appropriate grade stainless steel for the intended use of their product.
What are ferritic stainless steels?
Ferritic stainless steels contain a high chromium content with low carbon content and in most cases very little nickel content.
The main alloying element is chromium, with contents typically between 11 and 17%.
Carbon is kept low which results in these steels having limited strength.
They are magnetic.
Stainless steel grade 430
Grade 430 is the most common ferritic stainless steel grade in sheet form.
Properties
- composed of approximately 17% chromium
- O.K. corrosion resistance
- nickel is not present
- magnetic
Grade 430 stainless steel does well indoors.
Mild detergents and cleaners can be used on this grade.
Applications
- cutlery
- kitchen utensils
- catering equipment
- microwave oven liners
- induction heated pots and pans
- cooker hobs
- 17% chromium
- 1-6% nickel
- 0% molybdenum
- 5-15% manganese
- 0.25-0.4% nitrogen
- NOT chlorine resistant
- least corrosion resistance
Grade 304
- 18% chromium
- 8% nickel
- 0% molybdenum
- NOT chlorine resistant
- better corrosion resistance
Grade 316
- 16% chromium
- 10% nickel
- 2% molybdenum
- IS chlorine resistant
- superior corrosion resistance
Grade 430
- 17% chromium
- 0% nickel
- 0% molybdenum
- Fair corrosion resistance
Martensitic Stainless Steel
Although this is not considered a type of food grade stainless steel, there are some applications of this type of stainless steel that can be found in the kitchen.
Properties
Carbon is the key element in martensitic steels. The higher the carbon concentration is, the ‘harder’ the stainless steel will be.
Carbon levels can vary from less than 0.1% to over 1%.
The corrosion resistance of martensitic stainless steels is generally lower than
the other types of stainless steel.
Applications
The combination of high strength, good toughness, and moderate corrosion
resistance allow martensitic stainless steel to be used in a wide variety of applications
including:
- blades and cutting tools
- surgical instruments
- razor strips
- cutlery
Summary of the different types of stainless steel
Austenitic
- 18% chromium
- 8% nickel
- most commonly used stainless steels
- non-magnetic
Ferritic
- 10.5-18% chromium content
- magnetic
Martensitic
- 12-18% chromium
- high carbon content
- 0.1-1.2% carbon
- magnetic
Q&A TIme!
All of your food grade stainless steel questions answered!
Is Food Grade stainless steel magnetic?
Ferritic and martensitic grades of stainless steel are magnetic. Austenitic grades are not magnetic due to their nickel content.
Does Food Grade stainless steel rust?
Stainless steels are corrosive resistant due to their chromium content. However, with the addition of other elements, they do have a range of corrosion resistance.
In order from most rust resistant to least rust resistant, here is a list of food grade stainless steels:
- Austenitic (grade 316 is more corrosion resistant than grade 304)
- Ferritic
- Martensitic
What is food grade stainless steel made from?
Food grade stainless steel is made from different metal alloys and elements depending on the properties desired for the stainless steel, such as:
- nickel
- molybdenum
- titanium
- manganese
- copper
- carbon
- nitrogen
Does Food grade stainless steel contain nickel?
Austenitic stainless steels contain nickel. Most other types do not.
Is 304 Food Grade stainless steel?
Yes, it is an austenitic stainless steel and is considered food grade.
What types of food grade stainless steel are:
- Bowls: Austenitic – Grade 304
- Canteens: Austenitic – Grade 304
- Containers: Austenitic – Grades 304 or 316
- Cookware: Austenitic – Grades 304 or 316
- Countertops: Austenitic – Grades 304 or 316
- Cups: Austenitic – Grade 304
- Dinner Plates: Austenitic – Grade 202 or 304
- Dog Bowls: Austenitic – Grade 304
- Electric kettles: Austenitic – Grade 304
- Frying pans: Austenitic – Grades 304 or 316
- Knives: Martensitic or Ferritic – Grade 430
- Lunchboxes: Austenitic – Grades 200s, 304 or 316
- Pots and Pans: Austenitic – Grades 304 or 316
- Skillets: Austenitic – Grades 304 or 316
- Straws: Austenitic – Grade 304
- Travel Mugs: Austenitic – Grade 304
- Utensils: Austenitic – Grades 304 or 316, Ferritic – Grade 430, or Martensitic
- Water Bottles: Austenitic – Grade 304
What is the best food grade stainless steel?
That depends on what the stainless steel will be used for. There is no cut-and-dry answer to this question.
For example, if you’re looking for a high-quality knife, martensitic would be tougher than an austenitic grade. However, if you’re looking for a water bottle, austenitic grades would better since they are more resistant to corrosion.
How Do you Clean Food grade stainless steel?
For general household use, wash with a mild detergent (such as dish soap) and use a soft, non-scouring cloth to help keep the surface scratch-free.
For industrial use, a specific stainless steel cleaner may be more appropriate.
Where do you buy food grade stainless steel cleaner?
Stainless steel cleaner can be purchased from most department stores such as The Home Depot, and Walmart. It can also be found on Amazon here.
What are food grade coatings for stainless steel?
In this instance, the term food grade refers to a finish that is safe for processing food products and can easily and reliably be cleaned and sanitized.
Fluoropolymers are the most widely used stainless steel coatings.
There are two main types:
- PTFE (polytetrafluoroethylene): also known as Teflon
- FEP (fluorinated ethylene propylene)
Benefits of Stainless Steel coatings:
- Resistance to hot water, oils, fats, and steam
- Withstands extreme hot and cold temperatures
- Non-stick container coating
- Makes for easier and faster cleaning
- Food prep equipment protection
- Quick mold release
What is food grade sealant for stainless steel?
Generally, sealant is used to seal stainless steel joints. It’s main function is to keep moisture out of unwanted places. Sealant is typically used on food processing equipment, appliances, and sinks.
Food grade sealants resist the growth of fungus, mold and mildew. They are also resistant to chemicals such as acids, alkalis and many solvents, as well as boiling water, fats, and oils.
Most food grade sealants are made from silicone.
How do you identify food grade stainless steel?
It is almost impossible for the average consumer to identify different types of stainless steel. Stainless steel manufacturers generally use chemical testing to differentiate between types of stainless steel. That’s not ideal for the typical consumer.
The one type of testing suitable for consumer use differentiates between austenitic and ferritic or martensitic types of stainless steel. It is not too specific, but will at least give you a general idea of the type of stainless steel in question.
That is the magnet test. Austenitic grades (200’s, 304 and 316) will NOT be magnetic, whereas ferritic and martensitic types will be magnetic.
Is stainless steel the safest cookware?
No.
While it is generally safe to use, it is not THE safest cookware available.
Stainless steel is an alloy (made from a combinations of different metals), so there is a potential of some metals, specifically nickel (which our body does not need or use) leaching into foods prepared with stainless steel cookware.
Leaching can happen with lower quality stainless steel cookware as well as higher quality stainless steel that contain a large amount of nickel. Although the amount of leaching is minimal, it’s something to be aware of, especially if you are allergic to nickel.
There are types of stainless steel cookware made from grade 430 (ferritic) stainless steel that do not contain nickel. These may be a good alternative for some consumers.
Is stainless steel toxic when heated?
No. It is true that leaching of nickel and chromium does occur when stainless steel is heated, however, they do not reach toxic levels. That being said, consumers with nickel or chromium allergies may have a reaction and should probably not use stainless steel cookware just in case.
What is the best stainless steel for food contact?
Although there is no specific answer to this question regarding all of the types of food grade stainles steel, there are properties that make some stainless steels more appropriate to use than others depending on the desired function of the stainless steel.
This study from Food Protection Trends is very thorough and informative. Here is an excerpt of there concluding remarks:
It is clear from the foregoing discussion
that not all stainless steels are
created equal. Fabricators/manufacturers
of food processing equipment must
consider food types, cleaning/sanitizing/
sterilization processes, and all environments
of intended use when selecting
stainless steel material types. Food processors
must be aware of the general
properties and of the diversity of stainless
steels. If the wrong type of stainless steel
is selected for severe use applications, it
will surely fail and cause processed food
products to be unacceptable for market
or human consumption.
Is Food grade stainless steel safe?
Yes. Although leaching of some elements of stainless steel (particularly nickel and chromium) can occur, they generally are not toxic or present in amounts that are unsafe for the average consumer.
As 430 stainless steel is magnetic, will this magnetic property affect one’s health.
No
Good topic and valuable knowledge. Your articles are very knowledge for me. You are also told about SS products. Thanks for Sharing this knowledgeful article.
Thank-you!
This is an excellent, informative article. Thank you. Are you able to say, even theoretically, how long stainless steel 304 grade should last for? I know that it depends on use and aesthetics, but is there any data on this? Many thanks! Marian
Thanks for your comment! I could not find any hard and fast number of years that 304 grade steel should last for however, it should last a very long time. Just keep in mind that it does not have the chloride resistance of 316 so if you plan on using stainless steel by the ocean or a heavily salted area, choose 316 instead of 304. I hope that helps!
I just patient on a product that lifts the funnel just high enough off the flask to let the air go out as you pour liquor in to the flask,it does not touch the liquor. So does it have to be food grade stainless steel
I am not sure, sorry. I would check with the FDA or some other food and drink governing body. Good luck!
So, if you are having to high of metals build up in your body, will food grade stainless steel still leach metal?
Hi,
Is a food grade stainless steel product (such as a water bottle, or lunch box) unsafe to use once rust has appeared? Can rust be removed safely from such surfaces?
You can try removing rust by rubbing it with baking soda and a splash of water. That’s how I remove it from my stainless steel sink anyways. I have a video here that explains: https://www.youtube.com/watch?v=XvYrzphOrs8
I would not use it anymore if the rust is on the inside and cannot be removed. Time for a new one.
Hi Kathy, loved this article. very detailed and knowledgeable. I still have 1 question. I watched a video by NutrionFacts.org, the guy said that 18/10 stainless steel has a higher standard electrode potential than aluminum and thus can leach a tremendous amount of aluminum in food. I wonder that how come an alloy of chromium and nickel can have high food aluminum concentrations since it has no aluminum in it? I am really sad because I have a ferritic stainless steel pan that I like to cook with to avoid aluminum. But now I fear that I would still be eating aluminum. So, is ferritic steel free from this electrode potential thing? I will really appreciate you for clearing my doubts. Thank you again.
Would 201 Stainless steel be acceptable for drinkware such as a thermos? Even if it isn’t the “best” option, would it still pass FDA testing?
Hello,
Thank you for your informative article on stainless steel! My question is whether SS grade 304 is safe for my dogs to eat and drink from bowls made of such. I certainly do not want them to suffer any consequences using them.
Stainless steel has been recommended for dog bowls, as plastics can apparently harbor bacteria, or often cause allergies!
I would appreciate your thoughts,
Hilda
Who assigns the grade to stainless steel? Can a manufacturer (eg, in China) stamp 18/10 on its steel merchandise even if it is not?
I applaud your scholarship! Great article.
Is coloured stainless utensils like spoon or fork safe to use?
This is the best / most comprehensive breakdown I’ve read about SS yet! Nice job! I’m curious if there is a standard gauge (thickness) used for different container applications in foodsafe SS – specifically in both 430 or austenitic 316 ss ? Examples would be 11 gauge, or 14 gauge? Is there any standards out ther?
Which is safer for food grade specially skillet? The stainless steel or carbon steel?
Hello, your blog is the most informative, so I came here to kindly ask you a question, and hope you will reply to me.
I wanted to buy water distiller, but this particular brand makes two types. The only difference between them is the type of stainless steal used inside the distiller. Whilst one has 304 stainless steal, the other used 316. So I cannot decide between 304 or 316, which one is healthier. As 316 uses Molybdenum and extra 2% nickel, what would be the safest and healer?
Thank you.
Can anyone tell me if a chrome sink drain plug is safe for my dog? I have a glass sink and a chrome sink plug and I use this as my dogs water bowl. Im wondering if the chrome sink plug will leach into her water and cause heath problems. Any advice is much appreciated.
What is the safest cookware?
Thanks, it is a good read, knowledgeable and non-commercial.
I’m worried about the type of Stainless Steel bowls I use for my cats. They do not have ‘food grade’ protection like humans I looked online and mainly the talk is about 18/8 and 304. I go to a pet store and no one knows anything. Not anyone actually.
So I have cat bowls marked 10/21 and an old bowl marked 02/12. Everyone talks about the make up of stainless steel and the numbers 304 and 400 series. These are NOT the numbers marked on stainless steel bowls or cooking pans. ie- They are marked 18/8 or 10/21 etc. Why don’t people talk about those?
I have no idea what the / numbers mean. They are the ONLY description on the bottom of any Stainless products. NOT the 304 or 400 numbers.
Great article. Thank you.
I had a stainless steel flat top grill with sides made for me using (I believe) 316 stainless. My question is: are the welds food grade? Will any leaching occur from them? Any info would be appreciated.
Thank you in advance.
Hi there- I was wondering about the safety of “microwavable” stainless lunchboxes. I do not intend to microwave it, rather use it as a regular lunch box. It seems that there is a layer of chromium oxide – I assume that this means there is a ceramic coating – is it safe to eat food that would be in contact with this?
Thank you! Excellent information, clearly stated in such an organized and easily understood way. You’re an amazing writer!
I was given a knife made of molybdenum/vanadium stainless steel.
Is this safe for food prep?
We have purchased and used a steamer made in China of Austenitic stainless steel. Before use we were instructed to boil water and vinegar in the pot and to scald all the other parts in the boiling water and vinegar after 10 minutes. My knowledge of Chromium being hazardous and these preparations gave me pause after use, that we might get ill effects from the steamed crab, should we be concerned?