This week, we’re taking a look at stainless steel cookware. Stainless is supposed to be one of the best and safest forms of cookware, but as I’ve said before, quality matters. So how do you know if one type of stainless steel is better than another? Is there a way to test stainless steel for quality?
Let’s find out!
Question of the Week
Martha asks:
I was reading your article about cookware.. Last year I bought a set of stainless steel pans. How do I know if they are good quality?… and according to the information they are top quality. I try with a magnet and it will stick all over the pan just not inside… How can I make sure they are safe to cook? I’m totally changing my non-stick for more stainless or cast iron. Thank you for all your info. I cook a lot with butter… I love it!
This is a topic that a lot of people seem to be unsure about—I know I definitely was for quite a while! You hear so many different things about stainless steel. Some say it’s totally safe and non-reactive. Some say it leaches dangerous heavy metals into your food. Some say it’s the best thing ever and the only cookware you should use. Some say it’s only safe if it’s magnetic steel, which it sounds like you’ve heard before. You might have even heard it from me—that’s what I thought was the best way to test for quality, too! I’ve since learned some more information that might help you out.
So, let’s start with that whole magnetic thing. This is a confusing topic!
What’s the deal with magnetic stainless steel?
The theory of the “magnet test,” is sort of this rumor going around in which you’re supposed to test the quality of the stainless steel with a magnet. But really what this tests for, is whether or not the steel is austenitic, or made of a metal alloy which contains chromium and nickel.
There are three main types of structures in stainless steel—austenite, ferrite, and martensite. When you see stainless steel labeled as 18/8 or 18/10 this is telling you how much chromium and nickel is in the steel. The first number indicates 18% chromium, and the second 8% or 10% nickel. The nickel is the key to forming austenite stainless steel. Both the 18/8 and 18/10 are therefore austenitic.
So the “magnet test” is to take a magnet to your stainless steel cookware, and if it sticks, it’s “safe”—indicating no nickel present—but if it doesn’t stick, then it’s not safe, and contains nickel (which is an austenite steel). It is true that if a magnet were to stick to the steel, that it would not be a nickel (austenite) alloy.
There’s a problem with this theory, however. For one thing, there are no stainless steel pans which are magnetic on both the outside AND the inside. Someone please correct me if I’m wrong, but I have searched and searched and searched, and have yet to come across a fully-magnetic piece of stainless steel cookware.
And there is a good reason for this—austenitic, or nickel-containing, non-magnetic stainless steel, is highly resistant to corrosion, which is super important if you’re cooking directly on it. If the piece was fully magnetic stainless steel, it would corrode and not last very long without the nickel to stabilize the metal. Even though it would be nickel-free, I don’t think I would even want a magnetic, 18/0 stainless steel pan for this reason!
You will find magnetic stainless steel in the layer on the outside of some quality pieces of stainless steel. This is to make it compatible with induction stovetops, which involve the use of a rapidly charging electromagnetic field to heat cookware. High-quality stainless steel, good quality manufacturers use three layers of metal—the austenite layer of steel on the inside, ferrite steel on the outside, and a layer of aluminum sandwiched between the two for optimal heat conductivity (steel alone does not conduct heat evenly). Lesser-quality stainless steel is usually just one layer of austenitic stainless steel.
But there is still a difference in quality between the types of austenitic, or non-magnetic, stainless steel. You’ll sometimes find that austenitic stainless steel is weakly magnetized, and that’s because of the manufacturing process. You can actually form ferrite and martensite by “cold-working” the steel, which does make it more prone to corrosion and leaching.
The formulation of austenite in high-end, quality stainless steel cookware is created with a process which is careful to avoid this. It leads to an austenite alloy which is very stable and resistant to corrosion and leaching of metals. I’m no metallurgist, but in my opinion, a carefully-formed and highly-stable, non-corrosive, nickel-containing stainless steel is safer than a purely magnetic stainless steel which could break down and corrode over time. (And which doesn’t even exist on the market, anyway!)
If you know anyone who has had good quality stainless steel cookware for a number of years, you can tell just by looking at it compared with cheap stainless steel, that it is indeed very resistant to corrosion and holds up well over time.
But, to answer your original question,
How do you know if your stainless is high quality?
Well, unless you’re a metals expert and go inspect the factory where the steel is made to see whether or not their manufacturing process creates a pure austenite without corrosive materials formed, you’re not going to know for sure whether or not the craftsmanship of your stainless is of the highest quality. I think your best bet is to simply buy high-quality stainless steel from the start, from a brand with a reputation for good quality. But, I think I have figured out one way that you can determine if the stainless cookware you already have is potentially reactive.
The Vinegar Test
I read that you can test the quality (or more accurately, the reactivity) of the steel by boiling some water with a tablespoon of baking soda in the pan for a few minutes. If the water has a metallic taste, then the steel is reactive and of lesser-quality.
But from what I’ve learned about stainless steel, my understanding was that it’s the acidic foods you have to worry about, when it comes to any leaching from stainless steel. And baking soda is alkaline. So, I decided to do a little science experiment and try a different test!
Here’s what I did:
I poured a couple tablespoons of plain white vinegar (which is of course, quite acidic) into two spoons — good quality spoon, and another generic stainless steel spoon I had lying around. I also put some of the vinegar into a glass cup as a control.
After a few minutes, I taste-tested the vinegar from each.The good quality spoon`s vinegar tasted exactly like the vinegar in the glass cup. But the vinegar in the cheap, generic stainless pan tasted like metal. Blech. The taste is still in my mouth as I type!
I’m pretty convinced my vinegar test is a decent way to determine the reactivity of your stainless steel. Try it out on yours and see if it passes! But if it doesn’t, I wouldn’t freak out over this. Just be mindful about cooking with very acidic things like tomato-based sauces and stuff, and avoid storing these foods in your stainless steel.
thank you to Emily Benfit at (http://butterbeliever.com/how-to-tell-quality-of-stainless-steel-cookware/)
People frequently ask me what stainless steel cookware line I recommend. My first response is to think twice before buying a full line. If you own a 21-piece set of cookware, I’ll wager that two or three of those pots get regular use but that the other pieces are crammed in the back of an overfull cabinet. Purchase only the pieces you really need.
Neither do I recommend buying a celebrity endorsed line of cookware. Unless, that is, you want a percentage of your purchase price going into the celeb’s pocket.
Rather than recommending brands (unless it’s a one of a kind product) here I provide some basic information you can use to make an informed choice about the most health-supportive stainless steel cookware. Let’s look at some of the obvious features and then we’ll go into a little more detail about your choices. Lastly we’ll discuss how to use your pot to insure its long life and to reduce its reactivity.
Stainless pots and pans are often reasonably priced and have these advantages:
However, unlike ceramic, enamel and earthenware pots, stainless steel is mildly reactive, which means that some of its nickel and chromium leaches into your food as it cooks. For non-reactive cookware options, see Healthy Cookware. For cookware to avoid, see: Toxic Cookware and Cutlery.
What you should consider when choosing stainless steel cookware:
How Does the Stainless Steel Pot Feel in Your Hand?
It’s helpful to visit a store to get a “hand feel” for the pots and pans. Are they well balanced and a good weight for you? Do the lids fit snugly and are the knobs and handles easy to grip, heat-resistant and sturdy? Although riveted (bolted) handles and knobs are more secure than welded ones, cleaning around bolts is more difficult. Very high-end cookware manufacturers use a rivetless construction resulting in a smooth interior surface.
How Many Layers Does a Stainless Steel Pot Contain?
As stainless is not a good heat conductor, a sheet of aluminum or copper is often sandwiched between the stainless steel to enhance its heat-conductivity. Or, alternatively, the bottom layer of the pot will be made of copper or aluminum. The number of these metal layers, termed “clad” or “ply,” is one consideration when purchasing stainless cookware. A layer-free pot containing only stainless steel will be lighter in weight and more prone to warp than a pot containing one or more additional layers of a more heat conductive metal.
Each extra layer increases the weight of the pan and desirable heat conductivity properties. For value and quality, most three-ply brands are perfectly acceptable. As the interior of any stainless steel pot contains only stainless steel, you need not be concerned about the underlying layers. Unless, that is, if your layered pot becomes pitted, grooved or worn to expose an interior layer, then aluminum or copper will leach into your food; and it’s time to replace that pot.
What Is It Made Of?
The actual stainless steel used in stainless steel cookware is an iron-based metal alloy that must contain 11% chromium and up to seven additional metals (but never lead or aluminum). Chromium provides durability and rust resistance. Although nickel is not required, it provides rust resistance, hardness and high polishing characteristics. (By comparison, both carbon steel and cast iron lack both chromium and nickel, and they are prone to rust.) The downside of stainless steel’s chromium and nickel composition is as these metals interact with food, they are mildly reactive. With proper care (as we’ll see in a future blog) you can keep their reactivity to a bare minimum so that, for most people, it will not be a health concern.
Is there a Warranty or Return Policy?
Quality cookware manufacturers offer a warranty; which, in some cases, may be a life-time warranty. Some also have a return policy.
Which Stainless Steel Cookware Series Is Best for Me?
300 Series
Look on the bottom of a stainless steel pot and you’ll see a grade stamped on it; this grade indicates its durability and resistance to rust and corrosion. Quality pots and pans are in the 300 series and designated as either 304 or 316. The 304 pot is stamped with either 18/8 or 18/10 which indicates how much chromium and nickel the alloy contains. Eighteen, the first number of the sequence, indicates the percentage of chromium; the second number indicates the nickel. Most stainless cookware is an 18/10 grade (18 percent chromium/10 percent nickel).
The material difference between a 304 and 316 pot is negligible. However, the less common 316 grade contains a small percentage of molybdenum ( Mo) and/or titanium (Ti). This makes it more pricy and more corrosion resistant. The 316 grade, also known as marine stainless steel, better resists erosion by salt water. Surgical steel is yet another term for this high-end grade as it is used in biomedical implants. Indeed, if a metal pin is holding a fractured bone together, you’d obviously opt for a corrosion-free pin.
400 Series
Stainless steel from the 400 series is more corrosive than that from the 300 series and therefore will rust with age. It is primarily used in mixing bowls, kitchen utensils and inexpensive stockpots. For a more long-lived pot, opt for one from the 300 series.
The 400 series includes the so-called nickel-free stainless steel cookware, 18/0, which still contains a negligible amount of nickel (0.75%); and therefore people with rare nickel sensitivities are cautioned against using all stainless steel cookware including that from the 400 series. As nickel is not magnetic, you can tell if the pot’s interior or exterior contains nickel by placing a magnet against it. Any nickel-free portion of the pot will hold a magnet. (To be compatible with induction stovetops, the bottom of a stainless pot must be nickel-free.)
Minimize Reactivity in Stainless Steel Pots
As stainless is mildly reactive, here are three tips to minimize its reactivity.
A note on “vapor” or “waterless” cookware: Various lines of cookware labeled as such are designed to enable a type of steam cooking. A plus of stainless steel cookware is its versatility; it’s excellent for braising, frying, sautéing, steaming, simmering, boiling and parboiling, so to purchase a whole line of cookware that is designed for only one cooking style doesn’t make sense to me.
I hope this rundown helps you sort out your options, and may the one best suited to your needs and budget soon be getting plenty of action in your kitchen.
Coda: Cookware is only part of the story of cooking and healthy eating, albeit a very important part. Now making sure that the food going into those pots is “right” for you is the most profound way to influence your health. My Face Reading blogs will guide you; or consider ordering a Face Reading Report from me.
May you be well nourished,
Rebecca Wood
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