Why is cooking with copper better than cooking with stainless steel?

Well, apart from just looking so crazy elegant, there’s this physics thing. We go into this in some detail on our Fundamentals page, but here’s the convenient shorthand: Copper is 25 times more thermally efficient than stainless steel. Heat goes in and out of copper as you want and need it. Short of solid sterling silver, there’s no better metal in which to do everything you could conceive of doing in the kitchen.

Less esoterically, tin linings are a lot less sticky than stainless steel. Tin is a pure, elemental metal – very simple. Stainless steel is an alloy of several different metals, mostly iron, a bit of carbon, usually 18% chromium and 10% nickel (18/10 food grade stainless steel), and often titanium and molybdenum for hardness. No matter how smoothly the surface is apparently finished, at the microscopic level stainless steel is very complex. As anyone who has used stainless steel cookware knows, this makes for a very sticky pan.

Finally, the superiority of copper is not merely our opinion. In addition to being the choice of Michelin-starred professionals, culinary avatars, such as the late Craig Claiborne and Julia Child, accept no substitutes:

“The real treasure is solid professional-weight copper lined with tin… a solid copper stock pot with tin lining, pounds heavy saucepans of various volumes. The cost is a king’s ransom, but this is Tiffany-value stuff and will last well beyond the present lifetime of anyone reading this.”

– Craig Claiborne, Craig Claiborne’s Favorites from The New York Times, 1975

“Copper pots are the most satisfactory of all to cook in, as they hold and spread the heat well and their tin lining does not discolor food….. To get the full benefit of cooking in copper, the metal must be 1/8 inch thick, and the handle should be of heavy iron.”

– Julia Child, Mastering the Art of French Cooking, 1961

Note: 1/8 inch is equivalent to .125 (see above), or 3.2mm.

Why is quality copper cookware so expensive?

As of this writing in Spring 2021 copper, along with other industrial commodities, has been trending upward to about $4.30 per pound, a 75% increase on the previous year. That price gets rolled into the copper sheet we purchase at around $15.45. Our mill uses the futures market to “hedge” what they pay to recyclers and bulk ore processors, meaning they can buy or sell copper based on what they think the price of the metal will be a few months or even years from now. That allows them to smooth the price they charge their customers. Copper’s “spot” price goes up and down, but the price we pay is an average of about 24 months of rolling copper prices, i.e., relatively flat over time, which allows us to plan production going forward, knowing pretty closely what we’ll pay for materials.

Mills add value, which for BCC occurs as a specific crystalline formulation of pure copper sheet. Rolling raw smelted copper ingots into simple 3mm sheets doubles the price per pound, then tempering and treating it in the way we need for pan-making nearly doubles the price again.

Let’s take as an example our sauté pan, with its nearly 8 pounds of copper. Each of the cuts used to form the sauté are sheared from a very large sheet. Like when cutting biscuits, there are drops and irregular shapes that can’t be used for pans, so we return these to the mill as scrap for recycling (for which we get credited not the improved price we paid for it, but the current spot price). Between shearing, spinning, cut-back milling, drilling, riveting (all by hand) and other labor costs, the value added to our sauté bumps up about 75%.

Our cast iron handles and copper rivets add another 10% (“ductile” iron is itself subject to similar market swings, but with no futures market to smooth long-term prices), and then the copper pan body with its riveted iron handles are sent over to the tin shop for lining and polishing. While tin (in its highly purified “lab-grade” form by far the most expensive metal of the three we use) is not a large percentage of the weight of any pan, hand-tinning and polishing are the most labor-intensive operations in our production, adding another 45% or so to our sauté pan’s cost.

Then there are packaging, trucking various parts and assemblies between five different shops spanning Wisconsin to Indiana to Ohio, our little bit of marketing, administrative overhead, taxes and profit. On our $480 sauté we currently have profit dialed in at a little under 20%. At $800 our casserole nets us about 21%. Hand-making necessarily limits our production volume, but when we eventually hit our stride we look to make about 38% net across our complete Batterie de Cuisine.

As a vertically integrated designing and manufacturing retailer, our ~20% markup on cost of goods sold is quite small (markup for retailing alone is usually 90-100%). By selling our heavy weight sauté directly, and appealing to those who already appreciate the value of solid copper cookware, we can stay very lean. We negotiate pricing with our smiths, but we also want (and need) them to thrive on the work they do with us, so we won’t ever pick away at their margins to boost our own. We intend to stay lean to keep our prices for 100% American hand-made copper cookware not only competitive, but fair to all stakeholders. Our numbers will never amount to BCC making a killing (especially in a niche market), but they do allow all of BCC’s crew to make a decent living, and cooks everywhere to make better and better meals.

What do you mean by .090 and .125 thickness? Other makers (Mauviel, Matfer, Baumalu, etc.) measure in millimeters, why don’t you?

The key to thickness in copper cookware is to make a pot bottom thick enough to uniformly and finely distribute the heat energy coming into it without slowing it down. Copper is so thermally efficient that it moves heat 25 times faster that stainless steel, which means for starters one uses a lot less energy to heat the pan.

Copper thick enough to get a fine, granular distribution of that energy across the interior surface can also be so thick that it stores some of the heat energy, which when you’re working with, for example, delicate sauces, can be a problem. An efficient metal sheds energy as quickly as it takes it on, so when you want your food off the heat, it’s off immediately.

This is why people have strong opinions about thickness and why most high-quality copper cookware is between 1.75 and 3mm. It’s thick enough to distribute energy uniformly, but not so thick that it stores too much of it, and what it takes in lightning fast it can get rid of just as fast. At about 3.25mm in thickness one begins to lose the fast heating advantages with no significant gains in distribution – the pot is just that much heavier and more expensive.

Most of our pots and pans are fashioned from .090 – .125 thickness raw copper sheet. .090 thickness is the American-measure equivalent to 2.32mm, and .125 works out to about 3.2mm, but these measurements are meaningful only until we start hand-working the copper. The process of “spinning and tinning” (as we say) stretches and compresses the walls of a pan a bit in several dimensions. For example, as the flat sheet is smoothed up the sides of the lathe mandrel it stretches ever so slightly such that the finished wall of a tall pot (such as our stocker) could work out to 2.25 – 2.75mm. But the top edge of the wall will need trimming to its finished height, which also happens on the lathe and is done with a brass trim blade. This blunts the top edge of the pot at the opening and can work it out to 2.75 – 3mm. This thickening at the opening is not only visible, but has structural advantages – the thicker top “ring” increases the rigidity of the finished pot.

According to our caliper measurements only the floor of the pot retains the original sheet thickness. Tinning the interior adds approximately .2 – .4mm wall and floor thickness, for what we say is an overall finished thickness of approximately 2.5 – 3mm, with all variations around that number attributable to our hand-working processes.

What kind of glue is used to attach the tin to the copper? Is it toxic?

The physical properties of tin and copper allow them to form a bond without use of “mediating agency”, such as the cement that was originally used to secure stainless steel to copper, or a chemical catalyst which might leave a residue.

Before tinning, copper is “pickled” in dilute acid (usually hydrochloric, but in certain circumstances sulphuric or nitric) which not only completely cleans the copper but “etches” it microscopically. When the copper is then heated on an open forge (to a temperature below its melting point but above that of tin), this finely etched surface and a microns-thin film of cuprous oxide meets molten tin to form a crystalline film layer of bronze-like material, as a “phase” of the alloy more ceramic (Cu6Sn5) than metallic (CuSn), but not much more than a micron or so thick and bonded across both the copper and the tin layers.

Keeping the metals from curing too quickly in the process requires light applications of ammonium chloride flux (a mildly acidic, non-toxic, water soluble salt). All acid residues are burned off as the pan is heated on the tinning forge.

In order to keep molten tin from bonding to the pan exterior and handles during our lining process we paint a mask of colloidial clay and lime on these exposures, which is then washed off with plain water following tinning.

The final process to finishing a pan is polishing, when we apply increasingly fine graphite compounds to the exterior to flatten the original etching, fine production scratches and remaining masking, resulting in the classic smooth mirror finish characteristic of traditional copper cookware.

Why can’t I heat a tin-lined pan dry?

Tin begins to melt at approximately 425℉. An average range-top reaches its operating temperature (in the case of gas, 3500℉) quickly, and copper transmits it very quickly, so with nothing in it to absorb that heat the tin lining in our or any copper cookware will be damaged in the time it takes to crack a few eggs.

Of course, if you’re scrambling eggs you want the pan hot, so all you do there is make sure your butter or other cooking fat is in the pan first, coating the bottom. The burn point of most natural cooking oils is well below 425℉ so there’s really no danger if one just knows what’s at stake and what to do about it. Foodstuffs in the pan act as a heat-sink, meaning the energy coming into the pan flows into the stuff in it.

The same is true of browning; make sure food is in the pan before it gets hot and then the interface temperature between the pan’s working surface and the food you’re cooking stays right around the food’s transition temperature, which in the case of browning (the Maillard Reaction) is between 275 – 330℉. A very easy example is water’s boiling point, 212℉, well below tin’s melting point so with liquids in your pan you’re fine. The entire function of a pan used for cooking is to transfer energy, which copper and tin do with unsurpassed ease.

Now, tin alone tells you loud and clear when it’s in trouble, and even if it gets in trouble it won’t hurt you. Other cookware linings do not let you know as they’re breaking down, and the results of that can be very harmful – stainless steel delaminates, sometimes explosively, enamel (aka ceramic) fractures and chips off (also sometimes explosively), and, perhaps worst of all, non-stick linings outgas toxic compounds such as perfluorooctanoic acid. All can (often does) happen when any lined pan is heated empty. If you have to preheat dry (for example, to dry sear) please use naked cast iron or carbon steel. You can read more about all of this on the Truth About Linings page.

Gah! I heated my pan empty! You’re right, the tin got all bubbled and swimmy! Now what?

Chill. When you bought from Brooklyn Copper Cookware you got the skills to repair your wares in the deal. Damaged tin can be restored to new condition inexpensively (our retinning rates are among the lowest in the industry). Write or call and we’ll help you assess the situation, which at best may be no cause for alarm at all. The worst that can happen is you send us your pan, we fix it up good as new, and you start fresh.

That goes for all tin-lined copper cookware brands (and many nickel-lined) too. If you have a damaged or worn pan, jump over to our Retinning and Restoration page to read more about getting it some BCC TLC.

How about broiling? Can I oven broil in copper cookware?

Most oven broilers have thermostat presets of between 550℉ and 600℉. While the food in the pan will sink the heat in the filled portion of the pan, broilers are top elements in ovens, which is very likely to expose the top edge of any pan to the most intense heat. The top edge of both heavy cut copper cookware and lighter weight copper pans with rolled edges is tinned, and that tin can be damaged under a broiling element.

Generally speaking, one uses copper cookware “low and slow” (as we like to say), meaning copper is the metal of choice for delicate preparations and fine cooking control. As with other dry heat applications, we recommend carbon steel or cast iron for broiling.

Do you offer retinning services? What do you charge?

We re-tin any kind of copper cookware when the tin room is fired up to tin our own goods. When we can do certain pan types is based on what BCC wares are coming off the production line. There are always a bunch of retinning jobs in the queue, so it takes a little while (usually at least few weeks). You can determine your pots’ retinning needs by examining the interior surface for signs of copper showing through. The tin can be quite discolored owing to metallic conditioning and oxidation (a harmless darkening), but upon washing any actual openings to the copper walls or floor, if evident, will indicate the pot is due for refinishing.

If you’re unsure, letting a splash of vinegar dry on the suspicious surface for a couple of hours will usually reveal thin spots as a light green-ish (verdigris) streak. Now and then we receive a pot that still has years of wear left in its tin lining, so we like folks to be sure their pots need the work before they incur shipping costs (which, given the weight of some copper cookware, can be considerable).

We’re also able to tin pans that were originally lined in nickel. The procedure for stripping the nickel is a little more intense (i.e., sand-blasting is often needed), so only pans of 1.75mm thickness or thicker make good candidates.

Our reconditioning prices are $5.50 per linear inch, wall + base (long axis) + wall. As an example, a pan measuring 2 + 10 + 2, or 14″, would run about $77. and your return shipping is on us.

The service includes acid striping, rivet tightening if needed, lining and multi-grade mechanical polishing. We can also usually recurve rims and remove dents that have not fatigued the copper. Our aim is for your pot to come out looking as close to new as we can get it.

From here you can read more about our restoration program at its dedicated page. Otherwise, don’t hesitate to contact us if you have further questions.

If you’re local to NYC and are not sure your wares need work, we love visitors and are always happy to perform evaluations in our Brooklyn office (at no cost). If you’re contacting us through the BCC website, it’s also possible to attach photos to the contact form, which allows us to assess most issues remotely. It’s worth noting that what may appear to be wear and tear is sometimes just the normal conditioning and maturation of tin and may require nothing more than touch-up most people are equipped to perform at home (see “How do I clean a tin lining?” below).

How do I clean a tin lining?

One of the nicer things about copper cookware is that it cleans up beautifully, and will last several lifetimes with a little attention.

A tin lining is highly non-stick, but even so you may occasionally have food adhered to the interior. Soaking with a few drops of dish-washing liquid usually does the trick. For food that has burned into the pan, often filling with water, boiling and adding a generous quantity of pure, unscented ammonia will break down carbonization over 24 – 48 hours (we recommend that the pan be let sit outdoors, as ammonia fumes are an irritant). Thereafter, gently remove the softened residue with a plastic scouring pad (Scrunge, or similar).

Otherwise, to keep a tin lining going strong for many years it’s vital to remember never to heat a copper pan empty (see above). This is good practice for all lined pans – certainly for plastic non-stick linings, but also for enameled linings on cast iron. Carbon steel and naked cast iron are the only materials safe to heat empty.

Tin will darken and smooth with time and use, a process referred to as conditioning, and this actually improves a pan’s performance slightly. If you like, you can brighten a tin lining with a simple galvanic technique. Fill the pan with water and bring to a boil. Removing from heat, dissolve 1 – 3 Tbsp each of non-iodized table salt and sodium bicarbonate (baking soda) in the hot water (this is called an electrolyte). Fold a sheet of aluminum foil into several layers such that it fits in the bottom of you pan, and push this down gently in the hot water. Use only a wooden spoon to do this, as other metals will corrupt the process.

Oxidized tin is the cathode (negative pole) in this reaction, and the aluminum is the anode (positive pole). The light current created from negative to positive reduces oxidation on the outgoing tin side, and increases it on the incoming aluminum side, such that the tin will brighten and the aluminum will darken. Give the reaction 10 – 30 minutes to equalize, and then remove the aluminum foil. It should be noticeably darker.

And the tin should be noticeably brighter; simply empty the pan and wipe down with a clean cloth. This process is completely non-toxic and safe, and assumes that the tin has been cleaned of food residues.

For more on how and copper condition and improve while you use your pan, check out our downloadable guide to copper cookware in use, Meet Your Metal.

How do I clean copper cookware?

For a copper pan body we recommend drying the pot as soon as you finish washing it. This keeps water spots from marring the finish. Also, washing the exterior promptly yields the best results and is long-term easier than allowing residues to build up. Generally, if the pot is still slightly warm, food residues come off more easily.

For light polishing, we use a 2 – 1 ratio of ketchup and fine salt stirred into a paste and applied uniformly. It’s important to note the ingredients in your salt; common table salts and even some putatively “pure” culinary salts contain anti-caking agents (especially silicates) that can scratch copper. Generally a fine, light-colored sea salt is a safe bet, but check your salt’s ingredients for additives such as silicon dioxide, calcium silicate, or sodium aluminosilicate (aka, sodium silicoaluminate).

Left for a minute or two, rubbed in gently and then rinsed in cool water, salt and ketchup will brighten your copper finish beautifully, and the method is completely non-toxic. For more intensive polishing, you may wish to add flour and vinegar to the mix (3 parts flour, 2 parts ketchup and salt, one part vinegar). This creates more of a paste and remains stable in position longer, thus allowing the acids more time to act on the copper. After a few minutes, rub in, rinse and wipe as above.

As a chemical alternative, we find Wright’s Copper Polish does the best job with the fewest caustic compounds and no abrasives. For a slightly less brilliant but more durable polish with low VOCs and caustic ingredients, we also think well of Flitz Metal Polish. For the toughest jobs, we like Red Bear, which is based on the same jeweler’s rouge we use for mechanical polishing. Note, Red Bear does contain caustics, so use caution and wear gloves! Also, commercial copper polishes should not be used on tin.

Even with disciplined polishing, copper will condition and harden with repeat exposure to heat and slow cooling, forming the characteristic patina of which die-hard copper fans are so fond. While a desirable property (it improves the metal’s already exceptional thermal efficiency), it can only be effectively “removed” by high-friction mechanical compound polishing, which is, in fact, re-etching the copper surface to refract light at a higher number of frequencies. Otherwise home polishing will always leave a bit of patina (which we love).

For more on how and copper condition and improve while you use your pan, check out our downloadable guide to copper cookware in use, Meet Your Metal.

What about iron handles? Don’t they rust?

In keeping with our pure metal ethos (and because they don’t have to spend weeks at sea in shipping containers), we do not coat our iron handles with plasticine lacquers, which are difficult to remove completely and frustrate regular maintenance (such as what you’re going to read about below). We do apply a thin layer of butcher’s wax following final hand buffing to make sure your BCC arrives to you rust-free, but butcher’s wax is soft (in the winter the polishing room is pretty cold) so it will wear off relatively quickly. Fortunately, looking after your cast iron BCC handles is very easy, and the attention you give to it (like winding a good watch or oiling good leather) pays dividends in the long run.

Your skin oils will go far toward keeping the iron handles rust-free, but we advise very occasional wipes with a clean seed oil, such as flax or grapeseed. Fruit and nut oils, such as olive, coconut, walnut, etc., which have a lot of aromatics, polymerize too slowly and eventually oxidize (go rancid).

To season, simply address the pot shortly after use while the handle is warm, not hot. 4-5 drops of oil on a paper towel, rubbed on all the iron you can see, including right down to where it joins the copper, will hold you in good stead for weeks to months. Re-season as needed.

Although one is less likely to have it in the pantry, an especially durable solution for treating your handles is carnauba wax – a natural, hard palm oil wax that polymerizes well at room temperature. To apply, prepare the handle by rubbing down with fine emory paper or 0000 steel wool (to remove other oils and traces of oxidation), warm the pan in a 250℉ oven for 10 minutes, remove from the oven and lightly apply carnauba wax (in block form), melting the wax into the handle. Liquified, carnauba penetrates the iron’s pores and as the handle cools, the wax polymerizes and forms a vapor barrier. Take care to apply sparingly, as too thick a layer will slicken the grip!

Even severe rust on an old pan is usually superficial. Rust (i.e., superficial oxidation) is in fact part of the patina of iron and like patination on other metals forms a barrier against further deterioration, so don’t worry about discoloration that appears to be embedded in the handle.

To remove rust use 0000 steel wool or fine grit sand/emery paper to simply rub down the offending spots, wipe with a clean, dry cloth and season as above. If in removing the superficial rust the iron appears pitted or manifestly decayed, this is then corrosion, the repeated application of moisture or caustic materials to untreated rust. The integrity of a corroded handle may be compromised, especially around the rivets. Even so, on a heavy copper body that’s otherwise in good shape handles can sometimes be replaced.

Finally, once you have a well-seasoned or waxed iron handle, the only thing to keep in mind is when washing: As one does with cast iron cookware, avoid using detergents or soaps on seasoned handles. The surfactants in even mild cleaners will break down the polymer chains and destroy the protective layer. If by accident this happens, simply run through the seasoning or waxing steps again (but don’t be surprised if you’re removing a fair amount of rust first!).

For more on how and copper condition and improve while you use your pan, check out our downloadable guide to copper cookware in use, Meet Your Metal.

Can copper be used on induction ranges?

Not without a ferro-magnetic interface plate. These are commonly available, and we recommend either stainless steel or heavy carbon steel. The magnetic disturbance field heats the plate, and that energy in turn flows into a copper pan much as a coil or radiant energy source would.

Otherwise, copper is non-magnetic and therefore does not participate in the magnetic field generated by an induction cooktop. Stainless steel works best here for precisely the reasons it moves heat energy so slowly – it is a highly energy-resistant metal. This combination of magnetism and energy resistance is what causes a stainless steel pan to heat on an induction range – you can think of the pan’s resistance as providing the equivalent of friction to the current of energy flowing through it. The effect is very fast, and stainless steel on an induction cooktop heats with the speed of copper on flame. In truth, stainless steel on induction is more efficient than copper on a steel interface on induction, because the magnetic field activates the pan internally across its entire thickness immediately. There is zero penetration lag.

(2018 edit: Panasonic has introduced a non-ferrous compatible induction cooktop, reviewed here)

When it comes to trafficking a magnetic current, the resistance of stainless steel is a feature rather than a bug – the principle upon which induction succeeds, and is why stainless steel pans intended to be used on induction ranges are generally thicker (for ferrous metals thickness correlates with resistance). Unfortunately, induction ranges do not provide a way to reverse that energy gain, meaning once a thick stainless steel pan gets hot, it holds the energy that has gathered in the metal despite being taken off the induction field. Food, in other words,continues to cook in an induction heated stainless steel pan much as it does when heated conventionally. Energy does not begin leaving the pan until the metal and food temperatures equalize, and even then heat flowing from the food into stainless steel before dissipating is slowed by both the low emissivity and low thermal efficiency of stainless.

Copper, on the other hand, equalizes quickly with the temperature of the food it contains and allows thermal cooking reactions to reverse readily. In other words, your preparation stops cooking when you want it to. While induction can heat a ferro-magnetic pan very quickly, the combination cannot perform the reverse (and often equally important) function with anything like the efficiency of copper. To stop food from continuing to cook in ferric metal one has to get it out of the pan.

Do you ship internationally?

For the time being we’re able to calculate UPS shipping in our shopping cart only for destinations within the United States, however we’re happy to use the US Postal Service to ship internationally – we just have to arrange the shipment manually. Please contact us regarding your interests in getting BCC delivered wherever you are in the world, and we’ll get it set up.

Where can I see your wares? Why don’t you sell in retail stores?

For the time being we’re making our wares available exclusively on the web. This keeps our overhead down and allows us to stay nimble as we grow. We’re a tiny crew running this show from A to Z, and, frankly, it’s fun being tiny.

Which is not to say we don’t have aspirations.

As we grow we’ll still aim to satisfy our niche through means consistent with our general philosophy; kind of a variation on “less is more,” which sees the virtue of the human-scale. Mass production almost never shows up at the high end of any quality scale, which sometimes has to do with controlling supply in order to artificially inflate prices. In our case it’s more about wanting to preserve the close connection we have to our customers, wanting to work in the tight confines of Brooklyn, have dinner with our designer, or picnics with our smiths. We want to know who we’re working with and who we’re working for. We’ll never outsource any of what we do in order to “move more product.”

One of the nice things about making copper cookware is that what we make is very much like what one finds in innumerable fine cookware shops the world over: solid copper walls (ours are heavier than most), hand-wiped tin linings, cast iron handles (like none you’ve ever seen), that’s it. Kind of old-fashioned. In effect, if you’ve seen many of our French competitors’ wares, you know as much as you could know about the substance of ours (except ours is more substantial).

Maybe we’re cheating a bit by letting our competitors advertise the tangible value of copper cookware for us. People who bought our former Hammersmith line already seemed to know very well what they were looking for, maybe because they’d seen, held and even purchased our competitors’ goods. In most cases they had long experience with copper cookware, and therefore had well-developed instincts for what works best. To this we say “We know what you’re talking about. That’s what we make.”

We’d rather spend our money on tangible value for our customers instead of on advertising that tries to convince anyone they need us when they don’t already suspect as much. Another case of less is more.

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