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302 vs. 304 stainless steel in cookware

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Q. I was recently in the home of a friend for a cooking demonstration. In the demonstration, I was told that 304 is superior to 302 stainless steel for cooking basically because it was not reactive with food products and therefore would not leach into the food etc etc. The salesman attempted to prove this by dissolving sodium bicarbonate (which he called "pure sodium") into boiling water placed in various types of pans: 302, aluminum, glass, etc., and then having the audience taste the difference in the water to prove that 304 did not react but all of the others did.

The salesman also went to great lengths to convince us that it was possible for the aluminum (used in cookware to more evenly distribute heat) to leach through 302 stainless and get into the food.

Is any of this true or am I correct in my assumption that the salesman was ... "misguided"?

John Barile
consumer - Raleigh, North Carolina


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A. He is correct in saying that 304 is better than 302, but only slightly. 18-8 is even better but not used that much. He is absolutely wrong about the aluminum leaching thru in any detectable quantity thru the 302 or 304.

Snake oil salesman. Buy from him at your own risk. I would not, but that is me.

James Watts
- Navarre, Florida

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Q. I read in a "stainless steel" website that 304 contains 18% chromium and 8% nickel, thus it is commonly referred to as 18/8. However, James Watts of FL seems to be saying that 18-8 is better than 304, which means 304 and 18-8 are different? Can somebody clarify? In Malaysia, the stainless steel that we commonly see on cookware are only 18/8 and 18/10. Most of it comes from Thailand (Zebra Brand). My question is, which is better, 18/8 or 18/10?

Thank you.

Phillip Ooi
- Petaling Jaya, Malaysia


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A. 18-8 refers to a class of stainless steels including 302, 304, 316, 347 that have a chromium content of approximately 18% chromium and 8% nickel. They all have approximately the same corrosion resistance however the different alloys have different characteristics that make them easier to machine or offer more corrosion protection under different environmental conditions. 302 and 304 are frequently used interchangeably. The main difference is 302^304 has .08% carbon versus .15% for 304^302. Additionally 304 generally contains 1-2% more chromium than 302. I would guess any differences in cookware would be minimal.

Dale Neff
- Glendale, California


March 12, 2008

A. Dale Neff and Phillip Ooi almost got it right.

Both 302 and 304 are known as "18-8" stainless steels, as are several other of the 300-series stainless steels (300-series stainless steels are called "austenitic" stainless steels), the 18-8 referring to the "average" amount of chromium and nickel in their chemistries, and the min/max levels vary only slightly for the 302 (17-19 Cr) vs. 304 (18-20 Cr). .

However, 302-stainless is the alloy with the higher carbon content, not 304, and it should be noted, too, that these carbon contents are maximums only. Thus, 302-stainless has a maximum of 0.15 percent carbon, and 304-stainless has a max of 0.08 percent carbon (both alloys usually have less than their maximums). Because 304 stainless is able to control the carbon levels better, it is the most frequently used stainless alloy today, rather than 302.

Both of these stainlesses will perform very well in cookware, and one is not to be preferred over another from a metallurgical point of view as far as performance is concerned.

John Barile points up a common mistake many people make, namely that of believing everything they are taught. Obviously the salesman was saying what he was taught, and is a clear example of the blind leading the blind.

Take comfort in knowing that any stainless cookware you have at home is safe, does not allow food to leach through it, is highly corrosion-resistant, and should give you a lifetime of good service if not abused.

Dan Kay
metallurgical brazing consultants - Simsbury, Connecticut



Type 316 stainless vs. 304

September 10, 2009

Q. My friends and I are considering doing a group buy of T316 stainless steel mesh (10 strand) to use in food dehydrators. I've been told (by someone at the manufacturing company) that the chromium and nickel levels are higher in the T304, and that the T316 would be safer for this application. Does anyone have any information about that?

Julie Mallalieu
hobbyist - Eugene, Oregon


September 10, 2009

A. Hi, Julie. No, the reasoning is not correct, as you can see from the previous postings on the page. However, T316 is more corrosion resistant than T304 and the manufacturer may have been trying to make that point. Good luck.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

December 3, 2009

Q. T316 is more corrosion resistant than T304, then it should be better for cooking as salt over time would corrode T304 and other stainless steel cookware. If that happens, where is that metal going? I would think in our food and in our bodies like all the other cookware out there. Is this correct?

John Broussard
Construction - Lafayette, Louisiana


September 2014

A. Hi John. All stainless steel can be corroded by salt eventually, although 316 is probably slightly more resistant. It would be extremely difficult to estimate what percentage of those molecules are ingested vs. poured down the drain as cooking water vs. scrubbed off by cleaning. I think the best thing to say is that pots tend to last decades with little visible wear, and hundreds of millions of people have had their food cooked in pots for their entire lifetime without any obvious issues. Plus, most of the material of the pots, including the iron and the chromium and the nickel, are essential micronutrients, not poisons.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



July 26, 2012

Q. I am looking to manufacture 1/4" 20 bolt/nut hardware for outdoor usage (non-marine) and have the choice of using 302 or 304 stainless steel. I've seen conflicting information on the difference in corrosion resistance of these two grades.
The manufacturer is quoting double the cost of using 304 over 302.
Strength is not so much a factor as the bolt /nut combination does not have much of a weight load.
I have been buying 18/8 304 grade for other projects as this is readily available.
Looking for facts or experience of using 302 versus 304 material to manufacture bolts/nuts.
Thanks.

Chris Clarke
- Park Ridge, Illinois, USA

September 14, 2012

A. There is no difference in resistance to general atmospheric corrosion between Type 302 (UNS S30200) and Type 304 (UNS S30400). For fasteners that are cold formed (cold headed), there is a modified grade such as Custom Flo 302HQ from Cartech that includes 3-4% Cu for reduced work hardening & improved formability. The official designation is UNS S30430, and it has similar corrosion resistance to the other two grades. There is no substantial difference in the cost between 302 and 304 relative to alloying content, so any differences being quoted must be due to different manufacturing processes, suppliers, availability, etc.

Toby Padfield
Automotive supplier - Michigan, USA



Question about T304 cookware [Ed. note: 316Ti?]

August 9, 2014

Q. I'm looking for really high quality Stainless Steel cookware, and have reviewed the great posts about 304 and 316 stainless. There is mention of T304 stainless but no real discussion of it. I understand the T means it has titanium. But what I don't understand is what are the benefits (or downsides), if any, of having titanium in stainless steel cookware.
Thank you.

Pier Charter
cook - San Francisco, California, USA
  ^- Privately contact this inquirer -^


August 2014

A. Hi Pier. Although there is a type 316Ti titanium-enhanced stainless steel, to my knowledge there is not a 304Ti. When people use the phrase T304, it's probably just an abbreviation of "type 304" rather than a reference to titanium.

There is not a lot of titanium even in type 316Ti stainless -- not over 0.7% at the most. As for what exactly it does, you can see Allegheny Ludlum's datasheet on it =>

Remember that companies generally want to induce you to buy their product, rather than to technically inform you. So the cookware manufacturer might even have picked a formulation on the basis of sales appeal (Titanium!) than on real technical advantage. Reading Allegheny Ludlum's discussion, I see no advantage to 316Ti which would both truly be significant and apply to cookware. But there is a lot more to quality than a recipe -- as a cook like yourself probably knows a lot better than the rest of us :-)

A charcoal study on paper by Renoir is significantly more artistic than the finest oil on canvas by your average art student. If the manufacturer has a reputation for quality cookware, then making it from 316Ti is fine. If they don't have a good reputation, I don't care what material they use. Best of luck.

Regards,

25850
pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



September 9, 2014

Q. I am intending to buy an oven which is to be operated under normal weather conditions and operated up to 300 °C. For the oven's body, between 302 and 304 stainless steel which would offer better performance during its service. Please reply with reasons.

Amit K Singh
- Hyderabad, Telangana, India


September 2014

A. Hi Amit. This thread includes some helpful guidance on that subject, in-depth answers from Dan Kay and Toby Padfield, and a general impression that the differences for most applications are probably trivial.

Please try your best to frame your inquiry in terms of what was unclear to you from the previous responses, rather than essentially starting over. If that isn't possible, please at least advise us of the premium that is being asked for one material over the other, so people can comment on that and keep the thread moving forward rather than circling its tail. Thanks!

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



October 9, 2014

As I read the beginning of this string , I realize that the person who received the cooking demo was not listening! What was said that 304 cookware ... where the 304 TOUCHES THE FOOD ... will alter the chemistry of the food slightly over 316Ti . The salesperson did not say that aluminum, sandwiched between the outside 400 layer and the inside 316 Ti would leach to the food in the pot. The point is that 316Ti, which touches the food, does not alter the chemistry of the food. The "Pot Test" using baking soda and water boiled in many different pots for 5 minutes and then taste tested reveals that the baking soda solution cooked in 316Ti takes like baking soda and water ... other cookware will have a different effect and you have to do the test to believe it. Try the gamut ... cast iron to glass/enamel to aluminum (yuk!!) and Anodized (yuk!) to non-stick coated/teflon to the lower grade cookware 304 ...to the superior cooking surface, 316Ti. 316 and 316 Ti is what is used to make medical instruments and medical implants -- the body does not reject them and for a good reason! So this whole string is blown out of proportion starting with a misunderstanding from the get go. I must say however, I totally enjoy reading the comments, especially from the experts on stainless steel. Thank you and I am so grateful to have stumbled upon this conversation. Buy 316Ti, it will CHANGE YOUR LIFE!

Liz Kovacs
- Lewiston, New York


October 2014

Hi. Thanks Liz, you're as welcome as anyone else to have your opinion posted here, but how do you know what was actually said (as opposed to what may be on some standard sales shpiel? It seems more likely to me that a demonstrating salesperson will spout whatever will promote the sale, than that someone will utterly misquote what was claimed.

Several people, including metallurgists, have told us that such demonstrations test brand new cookware against previously used cookware, so that what you're really tasting is the fact that boiling water and bicarbonate can leach tiny amounts of your last meal out of previously used pots -- proving not that one metal leaches more than another, but that pots which have been cooked in and then washed are not as clean as you might think :-)

Per our editorial standards, we deleted your recommendation of a specific brand. But are you a satisfied customer of 316Ti with no vested interest, or are you a rep? One reason our editorial standards discourage testimonials to specific brand names is that company lawyers tend to make threats about negative reviews but not positive reviews, which results in unbalanced and too glowing reviews of every brand that is mentioned ... so savvy readers discredit such testimonials anyway, and we end up consuming their time without offering them the education this site strives for. Thanks for your views.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

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