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Jun 7, 2013 08:17 PM

Clad Cookware Construction Cuestion

I just purchased a new fully clad tri-ply saucepan. Close examination revealed a poorly finished rim. It is slightly rough in spots, which is no big deal, I chalked that up to less-than-perfect polishing.

What did concern me is that it is quite easy to see the individual layers of steel and aluminum. The easiest way to describe it is to say the aluminum doesn't have a bright finish and it looks like the rim has two dark gray pinstripes running the circumference of the rim, where the aluminum meets the steel. I apologize for not posting a photo, but my wimpy camera wouldn't capture the close-up properly.

My question is - is this simply an imperfect polishing job or does it foreshadow possible future delamination or deterioration? I ask because another new pan has a fully polished rim; the pan has to tilted at just the right angle to see that there are three layers.

A related question - Is aluminum not corrosion-resistant? I checked my current older clad cookware rim and found that the aluminum layer is clearly visible, looks dull, corroded (like zincs on a boat's outboard drives, for those familiar with boats), pitted, dinged in places, and generally degraded. It is also no longer even with the steel; running a finger over the rim, it feels (and looks) like the steel sticks out a tiny bit, indicating the aluminum has receded. I've had most of my pans for 11 years. Is this simply the nature of tri-ply construction? Can hand-washing prevent it?

Additionally, I had a lid handle fall off this week and saw that all the lid handles show a greater or lesser degree of corrosion on the screws. The handle that fell off is one on of my most-often used pans, and it is 11 years old. But still, this was a surprise to me. Oddly, the screw heads (which are on the underside of the lids) are stainless and in perfect condition, but the body of the screw is aluminum. Likewise with the rivets holding the pan handle to the body of the pan. The rivet heads inside the pan are stainless, the rivet body itself is not.

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  1. Hand washing will prevent the degradation of the aluminum layer, and washing in a dishwasher will promote it. A dishwasher destroys aluminum (though I have seem other threads here where posters indicate otherwise). It destroys anything aluminum I have mistakenly put in it. I never never intentionally wash aluminum in the dishwasher. If your habit has been to use a dishwasher for your cookware for eleven years, it is quite likely that the aluminum screws were destroyed by the dishwasher. Actually, you might consider yourself fortunate that the cookware has lasted so long!

    Also, have you been using your cookware on the boat on salt water? Might be adding to corrosion problems.

    8 Replies
    1. re: janniecooks

      janniecooks, thank you.

      If what you say is true, I'm a little peeved at the manufacturer, who tells me it's fine to clean their stuff in the dishwasher. IIRC, most clad cookware makers say machine washing is safe. They ought not tell us this if it causes the aluminum to break down.

      If the best thing about tri-ply cookware is it's versatility surely the second best thing must be durability. I fully expected this stuff to last a lifetime; it's not throwaway entry-level stuff. On Monday I'll find out how good the warranty promise on it really is when I ask them to replace the broken led.

      1. re: DuffyH

        I live on a boat and wash in salt water for the last 5+ years. Aluminum rivets degrade due to galvanic reaction brought about by acidic or saline solutions. Which is why All-Clad switched to stainless rivets after the first couple of years.

        In the 40 years I have had some of my pieces, there has been minimal to no erosion. I do not put them in the dishwasher, even when I lived in a house with one. When the aluminum rivets loosened on my 2 qt pot, All-Clad replaced it without a problem. After 30 years of almost daily use.

        As noted in other threads, I consider my cookware as tools to be used and not as show pieces. None of my copperware has ever been polished. So my standards as to what is acceptible wear and tear over time is different from most.

        Good luck on the warranty. And who is the manufacturer? This forum was designed to impart information of this nature.

        1. re: INDIANRIVERFL


          Like you, I think kitchen art should be hung on the wall. I don't care how many little scratches and dings it gets, performance counts.

          Although the aluminum at the rim has lost some metal, it certainly hasn't affected performance, nor should it for some time. Eventually, 10 more years, 20, 50, 100? there might be enough loss of metal to affect lamination integrity. The handles will fall off before the sandwich is kaput.

          Might I ask you to take a close-up look at your AC rims and see what the aluminum layer looks like?

          I didn't mention the brand name up front, because I wanted readers to look just at the question in regards to the metal, not with any bias for or against the brand. I always intended to identify them in follow-ups like this. My pots are Calphalon try-ply, and have given me great service. I considered AC at the time, but the handles were a deal breaker. Even more so now that I'm in my 50's.

          1. re: DuffyH

            The new handles are horrible. I buy AC/Emeril for Dear Daughter at the thrift shops for no more than $12. Mine are the broad rusty ones from the 70's and 80's that do not twist in the hand.

            Checked in storage as well as what I am using now and there is minimal erosion. Less than 1/16th of an inch. Understand that I have accumulated a wide variety of AC due to Mom happily buying it at the factory, knowing I would be overjoyed at Christmas, Birthday, etc.

            The only ones that have not faired well are the lined copper oval pans. Salt on copper pits them quickly. Which is why they are off the boat.

            I can understand a concern involving food trapped at the rim or hitting it just right and starting delamination. I wonder what the differences are in the aluminum alloys used . Wish Dad the metallurgist was still around. Or my friends father who was in research at Alcoa.

      2. re: janniecooks

        It isn't the dishwasher that "destroys" aluminum, but the detergent used in dishwashers. Not all detergents do this. There are some which will not react with aluminum.

        1. re: GH1618

          Would you happen to know which brands might not cause corrosion?

          1. re: DuffyH

            I don't know. But aluminum should not corrode away. It normally develops a stable oxide layer. But if you use chemicals which react with aluminum, it's a different matter.

          2. re: GH1618

            Of course, it is the detergent, not the dishwasher per se. Dish detergents used for general dishwashing do not damage my aluminum, whereas dishwashing machine detergents used in the dishwasher do destroy aluminum. For whatever chemical reaction, reason, etc. the dishwasher is not the place to wash aluminum.

        2. From Wikipedia:

          "Corrosion resistance (of aluminum) can be excellent due to a thin surface layer of aluminium oxide that forms when the metal is exposed to air, effectively preventing further oxidation. The strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper.[7] This corrosion resistance is also often greatly reduced by aqueous salts, particularly in the presence of dissimilar metals."

          Aluminum will corrode if left to the elements over long periods of time, however, consider that the aerospace industry has long used Aluminum as one of the main materials in aircraft construction. Think of the American Airlines paint scheme, which includes a bunch of exposed aluminum. Also, consider the attached image of a Globe Swift (1940's era aircraft) which has bare aluminum.

          3 Replies
          1. re: skier

            skier, thanks for your response.

            <This corrosion resistance is also often greatly reduced by aqueous salts, particularly in the presence of dissimilar metals.">

            That's very interesting. During the entire time I've owned these pots, I've either had whole-house soft water or I've added salt to the DW to combat hard water. I don't know how salty soft water is compared to hard tap water, but that's someplace to look.

            1. re: DuffyH

              Here is some additional reading on Aluminum and corrosion.


              "You may have noticed that you never see aluminum
              corrosion in lakes, pools, food packaging products, etc.
              Typically, if you have seen corroded aluminum, it was in or near the ocean. While it may seem logical to draw the
              conclusion that the salt water must be corrosive to the
              aluminum, it is not. Salt water does not corrode aluminum
              because of its neutral pH. A saltwater solution can, however,
              be a major facilitator for galvanic or dissimilar metal
              corrosion, a more complex corrosive process."

              1. re: skier


                That's interesting reading, thanks for sharing. It left me with two new questions:

                "Its protective oxide layer can become unstable when exposed to extreme pH levels. When the environment is highly acidic or basic, breakdown of the protective layer can occur, and its automatic renewal may not be fast enough to prevent corrosion."

                1. How does dishwasher soap affect the ph of water?

                "Metals are ordered in what is known as the galvanic series." "The metal nearer the noble end acts as the cathode and the metal nearer the active end acts as the anode. The farther away the two metals are from each other in the series, the larger the voltage potential, and the more intense the reaction."

                2. In a salt-water environment, does stainless steel work as a cathode when it's near aluminum?

          2. I can see the layers at the rim of my All-Clad LTD2 French Skillet. I don't see anything wrong with that. It would be more complicated to manufacture with the edge covered with SS, and there would be no point to it, in my opinion.

            1. Hi, Duffy:

              Your question is like a midterm exam in a materials science or applied physics course.

              Yes, aluminum can corrode. The sure ways to make it corrode faster are (a) to repeatedly scrub or polish away its natural passivation layer; and (b) put it into physical contact with a dissimilar metal that will gall or set up a galvanic response.

              I would not worry about your pans' rims, but neither would I polish the rims much. As to the escutcheon surfaces, one would think that the maker thought about which metals to use before they riveted it all together.

              From my own experience, I think that aluminum and mild carbon steel play well together, whereas Al and SS often do not. Would you rather the handle fall off after 11 years, or deal with a small degree of incidental rust or discoloration?


              2 Replies
              1. re: kaleokahu

                Hey, Kaleo -

                <Your question is like a midterm exam in a materials science or applied physics course.>

                That's why I asked; I majored in Zoology with a Marine Ecology emphasis. Take me on a cruise and I'll tell you whether we're watching dolphins or porpoise surf the bow wave, but all I know about minerals is that diamonds are sparkly.

                <From my own experience, I think that aluminum and mild carbon steel play well together, whereas Al and SS often do not.>

                Is aluminum/carbon steel an option in cookware?

                1. re: DuffyH

                  Hi, Duffy: "Is aluminum/carbon steel an option in cookware?"

                  Not any longer, as far as I know. I have some 1950s vintage aluminum stockers at my beach house that have carbon steel fittings, which have held up very well.

                  Convenience and what passes for cleanliness rules in modern cookware design and production. Look at what has happened with cutlery--if it discolors or gets a spot of rust from inattention, the sky falls...


              2. UPDATE - I called Calphalon this morning and within 5 minutes was told my new lid has been ordered and is on the way.

                I had expected to be asked to return the broken lid, or perhaps send a photo. Nope. I gave the customer service rep my name and the usual digits, then briefly described the problem. That was it. I'm told my new lid will arrive within 10-15 business days.

                I'm giving Calphalon high marks for my excellent experience. And as noted, the pans still perform brilliantly, after 11 years of treating them as ordinary tools with the usual clanging and banging.

                2 Replies
                1. re: DuffyH

                  Outstanding!! Glad it worked out for you.

                  1. re: INDIANRIVERFL

                    Given this level of customer service, I may have to rethink Calphalon for my new cookware. Tri-ply is out, because I've lost just enough hand strength that the larger pans twist in my grip. The Contemporary line has excellent handles, although on smaller pieces they're shorter than I prefer. Perhaps I could put together a blended set that would suit me very well. I do like to reward companies that treat me fairly and despite the one lid mishap my pans have served me well.

                    I've read some reviews that mention the newer induction stuff isn't as heavy as what I've got. Easily checked by strolling into BB&B with one of my pans and my scale. That would raise a few eyebrows!