In response to my previous article on cookware, certain questions have come up. I answered one of those questions in an article on heat sources. This next question is about cladding, most popularly heard in tri-ply cookware.
Why Tri-Ply Cookware?
Why do we hear about the great benefits of cladding as in AllClad, or Tri-ply or 5-ply or 7-ply?
First the cynical answer. In an effort to use technology to its fullest and get the most money for their marketing buck, cookware manufacturers have created ever increasing multi-layered cookware. It wasn’t always like this though.
In the beginning, you had unclad or pure metals – cast iron, carbon steel, stainless steel and aluminum. You can still find cookware made of these simple, straight forward materials. In the case of cast iron or carbon steel you get excellent cookware that, when properly seasoned, give you quality naturally occurring non-stick surfaces that will last a lifetime. Aluminum can also be very good cookware depending on how the pan is constructed, which can also last for a lifetime. Stainless steel pans are, in my mind, less than qualitative cookware but represent a good monetary value.
Somewhere in the mid-20th century, engineers decided to bond or clad two metals together to form a more perfect union of performance and quality.
So What Is Cladding?
Cladding is the bonding of different metals together to increase the function of the cookware. The idea being that combining metals of differing heat capacity and conductivity properties will create a more efficient pan and improve overall thermal diffusivity. In simplest terms, heat diffusivity is the combined measurement of heat capacity, the ability of a pan to hold heat and the heat conductivity, which is the ability of a metal to conduct the heat across the pan area.
Copper pots and pans represent the best execution of 2-ply cookware. Copper pans are most often sold in North America clad with stainless steel. Hence it is 2-ply or two layers of metal. In its most efficient state, copper is simply coated inside the pan with tin. I do not consider tin on copper to be a cladding as the tin is simply melted and brushed on. Neither do I consider the application of a nonstick or an enamel coating as a “ply”, although in the purest definition I guess one could call it a ply. I only consider it a “ply” when it involves a metal layer being added or bonded to another.
Copper aside, 2-ply cookware can represent the more affordable side clad cookware and due to the this factor, more likely to not be the best functioning cookware available. It is more affordable because they use lesser metals bonded together, such as stainless steel inside and a thin carbon steel layer on the outside.
Some define bottom clad cookware as 2-ply; again, I guess that is true in the strictest sense, however for the purposes of this discussion I only consider the “ply” to be where metals are joined in a way that covers the majority of cookware surface. Bottom clad would be a thin layer of copper, used mostly for decoration or bottom clad could also be represented by a metal disk attached to a pan to help overcome the lesser metal of the pan itself. Adding a solid thick disk to the bottom of a pan can do a good job of improving the heat diffusivity along the flat cooking surface while not increasing the production cost and therefore consumer sticker price. Since flat interior where the actual cooking is done in a skillet and to a large degree, a saute pan, the disk can really be a useful addition. If we are talking saucepans or stockpots, the disk is less useful, but still better than a plain layer of stainless steel.
The best example here is AllClad. While there are arguments about who actually pioneered the process of cladding metals for use in cookware, AllClad has become the name most synonymous with the style. The most common construction of this style is two stainless steel layers sandwiching an aluminum core. The aluminum layer adds to the pan weight and provides the beneficial energy conductivity. You may also see a copper core sandwiched between stainless steel layers. Another and more rare combination is carbon steel as the core element typically between stainless steel layers. One can also find pans layered with stainless steel, an aluminum core and copper outer layer. However, in this configuration the thin outer copper layer is more for aesthetics than actual function. The price on the cookware is going to be based on the core element and the thickness thereof. For example, copper core will cost more than aluminum, which is normally more expensive than a carbon core. Another variable in price is the thickness of the core metal; generally, the thicker the core metal the more costly the piece.
I think you are beginning to sense a pattern here. Let’s see if you can guess the configuration of a 5-ply piece. Yes, stainless steel inside and out. Yes, an aluminum or copper core. That’s three. Stuck? Let’s try adding a metal not involved in the core. So let’s imagine a construction of stainless, aluminum, copper, aluminum, stainless. Of course other combinations of those elements could be seen where a core of aluminum might be surrounded by copper then stainless steel outer layers. You might also see silver in place of one of those interior layers as well. As you might imagine, the 2nd and 4th layers are very thin. If they weren’t thin, the pan would weigh “a ton” and be quite awkward to wield.
At this point, we are entering the realm of marketing evil. Some companies claim 7-ply construction, but use the same metal in repeated thin, bonded layers but most will use our familiar alternating layer pattern as seen above. We might see stainless, silver, aluminum, copper, aluminum, silver, stainless. And as we mentioned above, there are many permeations of these and other metals.
Is More Better?
Above, I gave you the cynical answer to why cladding. Before I give you the better answer, I think we need to answer the other question on your mind. Are all these other layers (5 or 7) really providing measurable benefit? In my opinion, no they are not. I believe that well made, well constructed 2-ply or tri-ply cookware is all one really needs.
Having said that, I find the sauce pans and saute pans made by Demeyere, which in the most popular lines have these 7 layers, are very well engineered and manufactured to a very high standard. Do I think these pans could be just as effective as tri-ply cookware designed using a copper disk carefully enclosed in a well engineered stainless shell? Yes. But then again I am not a Belgian cookware engineer.
In conclusion, there is real benefit to be derived from bonding metals together in the manufacture of pots and pans. By making use of core metals with good thermal diffusivity combined with more durable, easy to maintain metal exteriors, high performing pots and pans can make their way into the hands of ambitious home cooks at a reasonable price.