The naked truth about bare aluminum cookware

[Fat Guy]

I assume we're all in agreement that the aluminum-Alzheimer's link is bogus, and for those who think it's a concern I think that could be addressed separately, so moving on . . .

On the Sitram/All-Clad topic I mentioned that many if not most professional restaurant kitchens use aluminum cookware. Not anodized aluminum. Not Teflon-coated aluminum. Just aluminum, like this Lincoln Wearever stuff:

The major advantages of this kind of cookware are:

1. It's cheap. A Lincoln Wearever 10" fry pan is $23.70 at BigTray and, as its use in so many excellent restaurants demonstrates, is all you actually need to cook at a high professional level.

2. It's durable. The cookware depicted above, in use last night at Beacon restaurant in New York City, has been with the restaurant since it opened in 1999, under heavy commercial use on very powerful ranges and in a wood-burning oven.

3. It's lightweight. Although aluminum cookware tends to have thick walls, it's still very light compared to most other cookware.

4. Aluminum is a very good conductor of heat and has generally good properties for cooking. It's not copper, but it's quite usable.

5. The surface releases pretty easily. More on that later.

Now for open questions, which may also be disadvantages:

1. Does it need to be seasoned? The cooks I spoke to last night, and other people I've spoken to, have said that unfinished aluminum needs seasoning, just like cast iron. Is this true?

2. I hear again and again that aluminum is sensitive to acidic food and both wrecks and gets wrecked by anything acidic that you cook in it. Is this really true? I've witnessed one challenge to the hypothesis: last night, as seen in that first photo above, we cooked meatballs in tomato sauce for an hour in a 600+ degree wood burning oven with no noticeable interaction between the saute pan and the sauce. I've also challenged a similar hypothesis many times with cast iron, and have never seen a problematic interaction between seasoned cast iron and tomato sauce, which by all accounts is quite acidic.

3. How best to clean it? This is one area where I've never done well with aluminum. I don't use much unfinished aluminum (I have a lot of anodized, which plays by different rules) but I have a big stockpot and several half-sheet pans. The stockpot, if you scrub it with a metal scrubber, turns the washing water gray. The sheet pans are easily scratched, not that it matters all that much. What's the deal here?

[NancyH]

A great topic FatGuy! I have two vintage Magnalite roasters that are aluminum. I've always been afraid to cook anything acidic in them. Yet my friend Scott, who acquired the smaller one for me on Ebay, makes chili in his all the time. And my friend Linda does her holiday brisket w/tomato sauce in one.

I wrote to Magnalite and asked them about it - and got a lot of newspeak and doubletalk instead of an answer.

So - I eagerly await to see how others weigh in on this topic!

[Fat Guy]

That may introduce another variable: Magnalite is cast aluminum, as opposed to the typical restaurant product which seems to be formed from sheets of aluminum. I doubt it makes a difference but I guess it could. Does anybody know?

[heidih]

I picked up my first aluminum pot from Smart & Final (a small restaurant oriented big box type store) for a song after I saw the ladies at the local taqueria making their soups in it. It does react with some items, but that is all visual and you learn what your piece does. You can't beat the price and it does not spatter/hiss like my stainless one of the same size when I am simmering liquids. Mine has a padded handle which for a practically daily burner is nice. I tend to use it for heating single servings of soup; starting with stock and adding in.

[annecros]

I'm Anne, and I cook on bare aluminum from time to time.

The heat conduction is the bomb.

I've seen chemical reactions.

More radical than I have seen on cast iron? Nah.

I wouldn't bother to season it. Toss it and get another, although I have never had to do that with bare aluminum.

I can see it in the commercial kitchen. I mean, it's like Reynold's Wrap. Seen it in my own kitchen. It's like Reynold's Wrap.

Now, the thing that makes me think is cast steel, not the stainless kind but cast steel. Makes you go hmm.

Edit: I think it is also referred to as crucible steel. Very light, not shiny, durable, great heat conductor.

I may have to steal Mom's one day.

[gallucci]

...

Now, the thing that makes me think is cast steel, not the stainless kind but cast steel. Makes you go hmm.

Edit: I think it is also referred to as crucible steel. Very light, not shiny, durable, great heat conductor.

I may have to steal Mom's one day.

←

"white" carbon steel, like these?

I have been tempted to try one...

mark

[annecros]

...

Now, the thing that makes me think is cast steel, not the stainless kind but cast steel. Makes you go hmm.

Edit: I think it is also referred to as crucible steel. Very light, not shiny, durable, great heat conductor.

I may have to steal Mom's one day.

←

"white" carbon steel, like these?

I have been tempted to try one...

mark

←

It looks like it. I think yes. Older women sought them out because of the light weight. "Cooks as good as cast iron." I seem to remember them saying. These ladies would be arthritic, and sort of burned out on the whole hauling a cast iron frying pan around. Why would they call it "cast steel" instead of carbon steel though?

I just looked, and my one sort of smallish, bare aluminum pot is my chicken soup pot. It isn't right unless it comes out of that pot, and honestly, it does appear to have a season. Crazy.

I bought that pot on a whim, cheap, and thinking back on where I lived when I bought it, I can safely say it is better than a decade old. Maybe two decades?

[heidih]

annecros mentioned seasoning. The tag on mine suggested rubbing with neutral oil, bringing to smoke point and then wiping down, repeating a few times. I have done this.

[David A. Goldfarb]

As I mentioned in the other thread, my father had a few Leyse Toroware pots and pans that were standard restaurant ware at the time, and we used them, and my parents still use them all the time. Leyse has since been divided between Vollrath and a company called Hi-Tech Graphics. My parents also have some black anodized Calphalon, and I have a Club cast aluminum dutch oven that belonged to my grandmother and must be at least fifty or sixty years old.

As best I can tell, all aluminum pits. I would guess that this is caused by interaction with acidic foods, and the aluminum must go somewhere, so I'm guessing it goes into the food. Is it enough to make it taste metallic? Maybe. I haven't been using it myself for a while, and I don't use the aluminum dutch oven or an aluminum stock pot that I have for anything acidic.

The frypans have warped with use, but they're still functional, as long as one isn't too particular about having a perfectly flat pan. I know I've hammered them a few times over the years. The saucepans have remained flat, as has the cast aluminum dutch oven.

I used to cook sometimes in the boarding house in college, and we had aluminum pots and pans for the most part, and on the high heat of a commercial stove, it was possible to melt the aluminum. I think I noticed this while sauteeing peppers for a big batch of salsa, and I saw the metal starting to bubble where the handle met the pan. I would suspect that the handle is a different alloy from the pan, so it may have a lower melting point.

I've never seasoned aluminum or taken particular care about cleaning it. Scotch Brite pads, steel wool, whatever works, and if one sands off some aluminum in the process, just rinse carefully and finish cleaning with soap and a plain sponge.

[edited info about Leyse]

Edited June 28, 2009 by David A. Goldfarb (log)

[Fat Guy]

Another issue for some might be that on current-generation induction burners aluminum is a no go.

[mgaretz]

Aluminum oxidizes almost instantaneously upon exposure to oxygen (air) forming a surface layer of aluminum oxide. This layer is microscopic but it's very hard and pretty tough. (Aluminum oxide is what sapphires and rubies are "made of" and is used as a commericial abrasive. The "ceramic" knives and "steels", synthetic sharpening stones, etc. all all primarily aluminum oxide with binders.) When the layer forms it protects the rest of the aluminum from further oxidation by forming a barrier between the aluminum and the air.

The good news is that this barrier also keeps food from interacting with the aluminum. No chemical process in the ordinary scope of cooking will have any effect on the barrier.

The bad news is that this barrier, while hard and tough, is very thin. It can be abraded away by being scraped with a knife or utensil or with very harsh cleaning chemicals.

"Anodized" aluminum is aluminum that has been chemically and electrically treated to grow this layer of oxide considerably thicker than happens naturally. The result is that it now becomes almost impossible to penetrate, resulting in a very durable piece of cookware. In the process they can also add color (pure aluminum oxide is clear).

[Peter the eater]

Everybody should have some aluminum cookware in the kitchen. It's affordable, light weight, heat responsive, durable, 100% recyclable -- perfect for camping.

If you need a really, really big pot then aluminum is the answer. We make maple syrup in March using giant cauldrons made of aluminum. The use of cast iron would add hundreds of pounds and dollars.

Mgaretz is right on with the oxide, it accumulates on the surface in an additive and protective way. Iron, on the other hand, oxidizes (rusts) in a destructive way.

Here's what Health Canada says:

Canadians normally take in about 10 milligrams of aluminum daily, mostly from food. Aluminum pots and pans provide only one or two milligrams of the total. While aluminum has been associated with Alzheimer's disease, there is no definite link proven. The World Health Organization estimates that adults can consume more than 50 milligrams of aluminum daily without harm.

During cooking, aluminum dissolves most easily from worn or pitted pots and pans. The longer food is cooked or stored in aluminum, the greater the amount that gets into food. Leafy vegetables and acidic foods, such as tomatoes and citrus products, absorb the most aluminum.

[HungryC]

I'm a Magnalite user, and I cook acidic foods in it with no (discernable to me) problems. Aluminum heats evenly (I can make a roux with 3 pounds of flour in a giant Magnalite roaster with no sticking or burning), cleans easily using abrasives, and it's cheap-cheap-cheap. I also have bare alumnium 60-quart pots; they work great for boiling crawfish, crabs, and making huge pots of gumbo. I choose aluminum when I need a quick temp response--take an alum. pot off the heat, and it cools quickly.

As for longevity--I made headcheese while at my parents' house a couple of weeks ago, and I boiled some of the pork parts in an ancient pot with a serious patina. My mother pointed out that it was one of my grandparents' "wedding" pots, purchased as a set when they married around 1931 or 1932. Still going strong, it is ugly as hell, but just the right size and shape for the task at hand.

[slkinsey]

I agree that there are plenty of good reasons to use heavy gauge raw aluminum. As you say, it's light, excellent conductor, inexpensive, etc. Some thoughts:

2. It's durable. The cookware depicted above, in use last night at Beacon restaurant in New York City, has been with the restaurant since it opened in 1999, under heavy commercial use on very powerful ranges and in a wood-burning oven.

It's a certain kind of durable, it's true, especially if it's the extra-thick kind. That said, call me a bit skeptical that Beacon has never replaced a frypan in ten years. Those frypans, in particular, just don't look dirty and dinged up enough to have been abused for ten years.

5. The surface releases pretty easily. More on that later.

I'm not sure that I think it releases any easier than any other metal. I'll be interested to see what you say here.

1. Does it need to be seasoned? The cooks I spoke to last night, and other people I've spoken to, have said that unfinished aluminum needs seasoning, just like cast iron. Is this true?

I don't see how it can be true that it needs to be seasoned "just like cast iron" because it's quite clear that the pans you have shown have not been seasoned just like cast iron. Otherwise, they would be black throughout.

I hear again and again that aluminum is sensitive to acidic food and both wrecks and gets wrecked by anything acidic that you cook in it. Is this really true? I've witnessed one challenge to the hypothesis: last night, as seen in that first photo above, we cooked meatballs in tomato sauce for an hour in a 600+ degree wood burning oven with no noticeable interaction between the saute pan and the sauce. I've also challenged a similar hypothesis many times with cast iron, and have never seen a problematic interaction between seasoned cast iron and tomato sauce, which by all accounts is quite acidic.

Tomato sauce is somewhat acidic, but not all that acidic. And, of course, it depends on how you make it and how you balance the acids. Tomato sauce has a pH of around 4.9, depending on formulation. That's pretty acidic, because a pH of 7 is neutral and the pH scale is logarithmic. But, in fact, just about all foods fall on the acidic side of the pH scale. Red onions are about 5.3; bananas at around 4.8; cauliflower is 5.6; cucumbers are 5.2; and so on. Truly acidic foods are things such as McIntosh apples at 3.3, lemon juice at 2.1, cider vinegar at 3.1, wine can be as low as 3.2 or so, rhubarb is 3.1, and so on. These things can definitely react with aluminum.

On the other hand, in a commercial setting where the pan is constantly being used over high heat with plenty of fat and is cleaned in the right way (without too much concern for cosmetics) this can be minimized. And, of course, in a restaurant that has a million pans, if they find that one of the preparations they are making reacts in the pan, they can always use a nonreactive pan for that. But, in general, it's the constant "reseasoning" use over high heat that makes these restaurant pans less reactive than it would be for a home user. It's also true that home users need to make do with a substantially smaller battery. I'm sure Waldy wouldn't use that raw aluminum Windsor pan that the eggs are poaching in if he wanted to reduce down a ton of highly acidic pomegranate juice to make grenadine. But he very likely has some nonreactive pans around he could use for this. Home cooks don't necessarily have that luxury, which is why if you are only going to have one three-quart saucepan, it makes sense to buy one that is nonreactive.

3. How best to clean it? This is one area where I've never done well with aluminum. I don't use much unfinished aluminum (I have a lot of anodized, which plays by different rules) but I have a big stockpot and several half-sheet pans. The stockpot, if you scrub it with a metal scrubber, turns the washing water gray. The sheet pans are easily scratched, not that it matters all that much. What's the deal here?

This is not entirely clear to me. The dishwasher is not the answer, because when I have put aluminum sheet pans in the dishwasher, they have discolored and eventually pitted. How are they washing the frypans at Beacon? My guess is that they may be treating them a bit rougher than cast iron, but in essentially the same way (no scrubbing at all, in other words, and perhaps just rinsing/wiping them out if that's all it takes to get them ready for the next use).

For me, I wouldn't hesitate to cook on raw aluminum. And I think it makes a lot of sense in the professional kitchen. I'm not sure it makes as much sense in the home kitchen, where one wants more flexibility and days, weeks or months may elapse in between uses of a given pan as opposed to the minutes at a place such as Beacon.

[Fat Guy]

call me a bit skeptical that Beacon has never replaced a frypan in ten years.  Those frypans, in particular, just don't look dirty and dinged up enough to have been abused for ten years.

What I was told is that "most" of the cookware has been with the restaurant since 1999. I'm sure the collection has been augmented and some pieces have been replaced. There's no dating system on the individual pieces so it's hard to tell with any given piece, though they're all so worn down that I was only able even to find brand names dimly etched on a couple of pieces out of dozens I looked at. Presumably those were newer pieces, but beyond that indicator I just don't have enough experience with this sort of cookware to look at an individual piece of it and intuit its age.

I'm sure Waldy wouldn't use that raw aluminum Windsor pan that the eggs are poaching in if he wanted to reduce down a ton of highly acidic pomegranate juice to make grenadine.

There wasn't any pomegranate juice being worked with, however the berry sauce for the souffles was cooked in aluminum and sat on the stove reducing for two or three hours and was then kept warm in that vessel for the entire service -- another five hours. I'm not sure how acidic that sauce is, but in general they seemed to be using aluminum (or in some cases cast iron) for just about everything other than presentation/service pieces. There were a couple of clad stainless pieces around but they didn't seem to be deployed in any particular pattern -- they were just grabbed randomly on account of being the next piece in the stack, I think.

How are they washing the frypans at Beacon?

When a pan gets dirty, you throw it in a bin on the floor. Eventually, a guy comes around and takes the bin away. A few minutes later he comes back with clean frypans and puts them on a shelf.

[paulraphael]

My biggest hesitation with aluminum fry pans and sauté pans is warping. Nothing subtle ... I'm talking about bulging, wobbling, smash-back-into-shape-with-a-hammer distortion.

I've had this happen to every plain or anodized heavy aluminum pan that i've used for sautéing. And with at least one saucepan. Counterintuitively, It doesn't happen with clad pans.

The aluminum oxide layer that prevents corrosion is vulnerable to both strong acids and bases. Once a pan starts pitting, it seems to continue to pit. The pits in the bottom of my calphalon saucepan (started as innocent dings when an ex commited some attrocity with a fork) are now craters. I've heard mixed opinions on whether the oxalic acid in BKF can halt this process.

Just yesterday I picked up a couple of used aluminum half sheet pans on the bowery for $2 each. One of them had clearly been through the dishwasher ... it's a moonscape of little pits. I'll be curious to see if they grow and turn the thing into lace.

Edited June 28, 2009 by paulraphael (log)

[Fat Guy]

I don't see how it can be true that it needs to be seasoned "just like cast iron"

Just out of curiosity I checked the Lincoln Smallwares website. In general, I've found that cookware manufacturers' recommendations make little sense, even for their own cookware. So I have no idea if this is useful information:

Seasoning

Both aluminum and stainless steel pans may benefit from seasoning, which means "to prepare for use". In this case, hot fat is used to create a stick resistance coating on the interior surface of the pan. This process may cause some harmless discoloration to the pan surface and may be used for re-seasoning the pan any number of times.

There were also some care guidelines:

Caring for Aluminum Cookware

Selecting a cleaner is the most important consideration when washing aluminum cookware. Strong alkali cleaners, such as lye, soda ash or trisodium phosphate discolor and corrode aluminum, even in weak solutions. A detergent containing an inhibitor should be used to prevent the cleaner from attacking the aluminum. Always use the cleaner in the proper solution according to the manufacturer's instructions. After washing, allow pots to thoroughly air dry before storing.

Removal of Food Acid Deposits from Aluminum Cookware If necessary, scrub area with an S.O.S. pad or scouring cloth. Prepare a solution of one tablespoon of baking soda to one gallon of water. Place solution inside the cookware to be cleaned. Bring solution to a rolling boil and boil for five minutes. Repeat steps 2 and 3 as necessary until stain is removed.

Removal of Alkali Deposits from Aluminum Cookware Scrub stain or burned-on food with an S.O.S. pad or scouring cloth. Prepare a mixture of one tablespoon of Cream of Tartar to one gallon of water. For exterior stains, submerge the cookware in the solution. For interior stains, place solution inside the utensil to be cleaned. Bring solution to a rolling boil and boil for five minutes. Repeat steps 2 and 3 as necessary until stain is removed.

Incidentally, the page I've quoted from begins with a fantastically amusing (to me at least) statement of the obvious:

Cookware plays a significant role in the foodservice industry because without it, most restaurants cannot operate.

[andiesenji]

I have several pieces of Magnalite (WagnerWare), including the monster roaster that I bought in 1969, and I also have Guardian ware, a couple of pieces of other Wagnerware cast aluminum and some less well-known brands.

When I got my first piece of Magnalite, 40-some years ago, it came with a little booklet that indicated how it could be used, including stovetop (over two burners) and also that it might discolor inside when cooking certain acidic foods. It turns a dark gray.

The instructions said that it was easy to get rid of this dark gray discoloration, if one found it unattractive, by simply filling it with hot water to just above the area of discoloration, bringing the water to a boil and adding

Cream of Tartar, 1 tablespoon for each gallon of water.

I have had various pieces discolor over the many years I have used these for cooking, canning (waterbath), roasting and etc.

The Cream of Tartar works. While it is an acid, it apparently is very good at stripping off the layer of whatever it is that has created the discoloration on the inside of the pot.

Incidentally, I found the same "hint" in a book of household hints from the late 1940s and when I mentioned it at one of my volunteer meetings at the local senior center, a WWII vet, who was a GI cook, said they did the same thing as they were using very large aluminum pots because steel was not available for cookware.

In this photo you can see the level where I last "treated" the roaster.

These are always available on ebay but they can also be found for much less at thrift shops and yard sales.

This is the 4269, they also made a 4267 and 4265, (large and medium). The 4269 is the largest.

It always has the incised name on the bottom with the number.

Edited June 28, 2009 by andiesenji (log)

[Edward J]

I've been cooking in kitchens around the world for close to 25 years now, and I hate, loathe, detest, etc. aluminum. Since I've been running my own business for close to 12 eyars now I have very little--if any aluminum cookware in my kitchens.

OH, Aluminum, why do I hate thee so?

I hate thee becasue you warp so badly. A brand new saute pan will turn into a wok within two days. Not so bad if you cook on gas stove, but with electric--forget it.

I hate thee becasue thine handles are riveted on. Aluminum has been welded for close to 40 years now, but mnfctrs are very reluctant to weld handles on, no they rivet them on. Problem is they use alum. rivets, which are soft. The rivets work themselves loose within months. So now for saute pans you have woks with loosey-goosey handles. If I had a dollar for every saute pan I "Fixed" by peening back the rivets with a meat hammer over a cement filled post in the parking lot of various employers I'd be a rich man by now.

But wait! There's more! When the rivets are loose, liquid escapes, and it escapes all down your fore-arm, (liquids can include hot oil too...) and spilling all over the stove. With large pots you can only fill to below the rivet line or you'll have an "automatic overflow device" spilling over and extinguishing your flame.

I hate thee because thou oxidizes. Everything the pot/pan touches turns black with icky oxidization: Countertops, shelves, clothes, and hands. You can never do a white sauce or soup in an aluminum pot if you want to use a whisk--you'll get a nice gey colour...

I hate thee becasue thou pits. Aluminum pits badly. All cookware--including s/s and enamel will pit if undisolved salt is heated on the surface. You can stop this by only adding salt into hot liquids and stirring. Aluminum pits far, far worse.

It isn't popular in Europe, becasue a lot of the kitchens there have electric ranges, and like I said, alumunimu warps badly, no-can-do on a flat electric range.

Why is so popular here? Becasue it's cheap. No other reason why

[cbread]

You say,, because:

...

you warp so badly...

thine handles are riveted on...

thou oxidizes... thou pits...

it's cheap...

←

I don't do restaurant cooking so I'm not qualified to answer about restaurant kitchen usage, but at home I have only managed to badly warp one aluminum pan when I did the dumbest possible thing and put a very hot pan bottom down in very cold water. It instantly warped. All my other alum cookware stays fine to this day.

With few exceptions, all my best cookware and all my cheeepest cookware have riveted handles. Welded would be much better but I suspect cost deters the makers.

Pitting and oxidizing? Hasn't been much of a problem. Continuous commercial usage would be different, but then, the cheapness would just mean toss it and replace it since it's cheap. For me, aluminum pans are throw away, but being a cheapskate Yankee, I still want to see how much mileage I can get from them.

[cbread]

... The instructions said that it was easy to get rid of this dark gray discoloration, if one found it unattractive, by simply filling it with hot water to just above the area of discoloration, bringing the water to a boil and adding Cream of Tartar, 1 tablespoon for each gallon of water. ...

←

Another vote for cream of tartar. It works better and easier than scrubbing; just mix and boil. I love the stuff.

Cream of tartar powder can be got in bulk for far less than the exorbitant levy at the supermarket spice rack. Search in Amazon for "Cream of tartar powder" The first result is less than $10.00 for a pound.

[paulraphael]

I've been cooking in kitchens around the world for close to 25 years now, and I hate, loathe, detest, etc. aluminum.  Since I've been running my own business for close to 12 eyars now I have very little--if any aluminum cookware in my kitchens.

What do you like?

[Blair P. Houghton]

On the imperviousness of aluminum oxide, well, it's not.

Acids typically act as reducing agents, stripping away the oxide (that's why a batch of tomato sauce cleans up your steel pans so nicely). But, once it's dry, the aluminum will react with the air to replace the oxide layer.

And aluminum's food-chemistry tricks aren't limited to ordinary acids.

Just for fun, boil up a batch of hotdogs in an aluminum pan, then leave the hotdog water (minus the dogs) in the pan overnight. The schmutz you'll find floating around in the water the next morning is aluminum nitrate, precipitated by the reaction of nitrates (hot dog preservatives) with the aluminum in the pan. The aluminum oxide layer didn't stop it.

As most have noted, the reactivity of aluminum isn't noticeable in most cooking, but it's there.

The point of anodizing aluminum is to take the oxidation process one step further, creating an oxidized surface that really is impervious to food chemistry, and most mechanical attacks. Anionic detergents like dish soap won't hurt it, but the cationic detergents in your automatic dishwasher can erode it over time, and you can actually buy products designed to strip anodizing from aluminum.

[Fat Guy]

I still don't feel we have an answer on the seasoning issue, but if it's true that seasoning creates a protective layer then the chemistry of aluminum is less relevant to the cookware's performance vis-a-vis surface interactions.

[slkinsey]

There are many kinds of "seasoning." When we speak of "seasoning" cast iron, we speak of selectively oxidizing the surface into magnetite (black iron oxide instead of rust) and building-up layers of polymerized fat mixed with carbon.

One potentially can season most any cookware this way, although it appears to be more difficult to get this kind of seasoning to adhere to certain base materials than others, and of course the oxidized . For example, it is not difficult to remove the seasoning from a carbon steel (aka blue steel, aka black steel, aka French steel, aka mild steel) using a scouring pad. This is perhaps because carbon steel is much softer than cast iron. Aluminum is softer still, and whatever "cast-iron type" seasoning one can build up on aluminum appears to be even less durable and persistent.

It sees quite clear to me that aluminum cookware is not typically seasoned in the manner of cast iron. Look at the pictures from Beacon. Do those look seasoned? They don't look seasoned to me. I don't see any ten years worth of built-up polymerized fat. What I see is the somewhat dull finish I would associate with oxidized aluminum. On everything except for the frypan, which looks fairly shiny to me -- and which I assume is of considerably newer provenance than the other pieces (large frypans are the most notorious warpers).

Considering that these pans are being washed any times a day, I think we can dispense with the idea that they are "seasoned" in the same sense that we consider cast iron to be "seasoned." Even if it were true, it's not the case that the seasoning of cast iron eliminates reactivity. It simply reduces it from what it would otherwise have been. Some people notice the iron taste in certain foods in cast iron, and some people don't. But, on a chemical basis, it's in there.

So, to whatever extent "seasoning" of aluminum happens, it's not the same kind that we do with cast iron. To whatever extent there is any "seasoning" of raw aluminum with fat, it is more along the lines of "filling the pores" once the cookware is heated and expanded.

As others have pointed out, metallic aluminum is one of the most reactive metals there is. But, when exposed to the atmosphere it almost immediately forms a layer of aluminum oxide (aka alumina) which is both harder and less reactive than aluminum. This layer isn't exactly durable, however, being a mere 4 nanometers thick and having soft aluminum underneath. It doesn't take much to scrape through the aluminum oxide, or for a strong enough acid to erode the aluminum oxide and expose the much more reactive metallic aluminum underneath. Certain foods can take on a gray coloration, and certain foods can take on a slightly metallic taste -- especially if, say, whisked frequently with a metal whisk. Now, depending on what you're cooking, and to a lesser extent what your sensitivities are, maybe you won't notice a difference. For most foods, it shouldn't make a difference. But sometimes it will. Plenty of people have covered a dish of tomato sauce with aluminum foil overnight only to find the nest day that the sauce has corroded a hole in the foil. That same thing happens in the pan. I admit to being a bit surprised that the berry sauce cooks that long in raw aluminum with no apparent negative impact. Perhaps the sugar level has some kind of protective effect or perhaps the flavors are so concentrated that any metallic flavor is unlikely to be noticed.

I agree that 90% of the things we might like to do in the kitchen can be done perfectly well on raw aluminum. I don't like aluminum frypans because they are notorious for warping (and no, you need not toss a hot pan into a cold sink of water to see this happen). The problem for home cooks is that, when you want to do something in the other 10% and all you have is aluminum cookware, you don't really have anywhere to go.