Kalyana rasam & the mystery-chemistry of the eeya chombu

This story has a few parts, turning convention topsy by starting with a recipe rather than ending with one. The eeya chombu kalyana rasam comes first, followed by sections figuring out what this object called an “eeya chombu” is all about–the association of tin and lead, the many cultural confusions assembled on top, then the chemistry of taste, and finally a summary of everything, including do-s and don’t-s and really-must-you-s? when it comes to owning an eeya chombu yourself. It’s a long post, reader beware. No guidance on how long it might take you to read it, but if you enjoy chemistry, or wonder about our innumerable cultural imponderabilia, love rasam, or wonder about your dulling eeya chombu or what the fuss about eeya chombu is all about … then this post just might be for you.

Here’s a basic fact to which almost no rasam-making Tamilian out there will offer a counter: rasam made in eeya chombus or tin vessels tastes amazing. Ah-may-zing, in fact. There is a specificity of vessels to dishes in most all Indian cookery, and so as the kal chatti [கல் சட்டி] is to vattha kuzhambu [வெத்த கொழும்பு] or tamarind-based dal preparations generally, so is the lighter, brothy rasam to the eeya paathiram. Magic.

But the eeya chombu is a special, hand-crafted object, priced by metal weight and pricey by any standards. So, for wedding feasts and other large crowd-cooking, there simply aren’t any large enough. The solution? Drop the eeyam into the rasam for a few minutes, and let it do its magic there. A.K. Ramanujan alluded to Indian narrative forms and stories within stories in this old favorite essay . The same applies here: it’s a case of the container, contained.

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My recipe here adapts Priya’s from her blog, which felt the most right to me, of all the kalyana rasam variants out there. Watery, low/no dal–so cost efficient, but also minimalist for the same reasons, and with no-fuss ingredients like tomatoes. And if made right, absolutely delicious.

What’s with the eeya chombu?

The eeya paathiram is (meant to be) a pure tin vessel, hand beaten because tin is soft, into a few different, classic shapes, of which the most common are vennathazhi–to churn butter, aduku–to nest within similar shaped vessels of larger sizes, the regular chatti–the ultimate gravy vessel, the kinnam–generic smaller-or-larger round vessel, and the chombu–classically for water; hence the association with watery-brothy rasam. Eeya paathirams are what would be called these days artisanal products, made largely by craftsmen around Kumbakkonam: an area known for temples and such handiwork. Traditionally part of a bridal trousseau, the eeya chombu is a heirloom piece, used over lifetimes, passed down in families.

The late Shri Parashuram Gode–Sanskrit scholar and inaugural curator of the Bhandarkar Oriental Research Institute (1916-1941) with one of the largest collections of ancient texts in South Asia–wrote that the use of solid tin vessels in India predates the craft of tinning. Kalai is a word of Arabic origin (calai or qalai) which refers to the art of tin-coating copper and brass vessels. As a technology it dates back to Roman times, but it was the Muslims who introduced it in India, possibly in the 1300s on the strength of mostly literary evidence. Gode says tinning became common by the 17th century. Up to the 20th century, the work of kalai application, “kalaya-lepa” or eeyam poosudal [ஈயம் பூசுதல்] was a fact of village life, undertaken by itinerant craftsmen going from village to village carrying thurithi (kaatru-oothi, bellows), creating makeshift kilns in public grounds, and releasing noxious smells which mark the event indelibly in memory, to be sure.

Watch the video snippet above from the 1994 film Periya marudhu, and you get a sense of just how much tinning practices were part village life and its cultural economy itself. Worn or old vessels could be re-lined or traded in; they were part of the older ways of recycling. Eeyam was a metaphor, here a ruse, there a sexual innuendo, and even a way to take political potshots. For example, this line by the Tamil lyricist and DMK bard, Nagore E. M. Hanifa: “otta odaisal eeyamputhalaikku peri-chambalam, namma naatai aalum manthirihalukku thenda-shambalam” refers to the fact that even useless eeyam has greater value than the useless ministers of the (opposing) party in government [Cited here].

Wait, but what is eeyam anyway?

Gode also finds an association of “kalhaikara” (or kalhaigar, the craftsman trained in tinning arts) with “sisakars” and surmises that perhaps “the Kalhalvalas of Shivaji’s time not only practised the art of tin-coating but of lead-coating also” (Source: P.K. Gode, 1969: 114).

This last note is of interest simply because it highlights the long-standing association of lead and tin; it brings me to the maligning of the eeya chombu as a source of possible human malady. Lead is of course among our earliest known and widest used metals. Its Latin name, plumbum, was one used to refer to soft metals generally–including tin. In fact, says a 2013 Nature article, “lead and tin were not clearly distinguished until the sixteenth century, when lead was referred to as plumbum nigrum (black lead) and tin as plumbum candidum or album (bright lead).”

In Tamil, too, “eeyam” refers to lead first and only then to tin. The two metals are distinguished only by a color qualifier: vellai eeyam [வெள்ளை ஈயம்/ வெள்ளீயம்] is white eeyam and therefore tin; karu eeyam [கரு ஈயம்/ காரீயம்] is black eeyam and therefore lead. To know which is being referenced, context is all-important. An article on ancient pregnancy terminations simply names “eeyam,” but that one understands to be lead.

This slipperiness of “eeyam” then makes me wonder: what was being sold as eeyam in the first place? The time-frame is roughly early-to-mid-20th century, when all this controversy seems to have fomented. That’s roughly my grandparents’ and parents’ generations, starting some decades prior to Independence. Was it really tin being sold–or lead? Lead lined, outside and in, with tin–the kalhaigar‘s specialty, after all? Or was it tin contaminated with lead? For even commercial grades of tin are known to “contain small amount of bismuth, antinomy, lead and silver as impurities” [Source: Johanna Feary and Paul Cullinan, 2019].

This last is a real possibility. The source of tin ore at this time would have been Malay cassiterite. British involvement in Malaya at the end of the 19th century was undoubtedly driven by their interests in controlling tin mining activity in Perak and Selangor (Yamada 1971), along the western coast. The area remains a major source of the world’s tin. Analysis of tin mineralization and accompanying mineral deposits in the region indicates “the significance [sic] presence of Cu-, Pb-, Sb- and Bi-bearing minerals” (Source: Ariffin: 287)–though it is unclear whether these contaminants would have been more in Malay tin than in what was likely used prior (from British sources). This comment on a fascinating Stack Exchange thread suggests this is the case & points out that purification of tin would therefore naturally increase cost. Merchants wouldn’t, I think, have hesitated to cut corners.

Another real possibility is the fact that what was being sold as eeyam was in fact neither lead nor tin, but pewter. Pure tin is expensive, soft (easily dented), and has a low melting point. Older pewter was 70% tin and 30% lead, with lead acting has hardener. It had a bluish tint, and “darkened greatly with age, and the lead readily leached out in contact with acidic foods” [Source]. The lower tin quotient in this low-grade pewter would have the reduced cost of a chombu considerably, even if it wouldn’t much have increased melting points. Finer grades of pewter had, and still have, little-to-no lead, but are alloys of tin, antimony, bismuth, and copper (in decreasing volumetric order, with tin being primary, around 90%, antimony and copper replacing lead as hardeners, bismuth to prevent shrinking in moulding applications). Sometimes, silver is added to the mix. This alloy has a brighter sheen, does not dull with use, and has both greater weight and a somewhat higher melting point than lead-based pewter [Source].

These two fact-sets about lower and higher grade pewter respectively correspond perfectly with some commonly reported experiences in India. First, stories of eeya chombus disintegrating on unattended stovetops are very common. This suggests they cannot have been just lead (since that has a melting point 100° higher than tin), but doesn’t confirm that the metal in question tin or a pewter alloy. Second, that many, many households simply shelved their eeya chombus on the logic that they stopped being safe for culinary use as they darkened and aged. It’s unclear how the safety assessment was made, or where the precise tipping point for retirement was identified, but heirloom pieces got stashed in cupboards nonetheless. Last, many shop-owners around Kumbakkonam, where these eeya paathirams are famously made, have often reported that “eeyam” is an alloy–but of what? Nobody quite says. The silence, the commonness of adulteration, and a general mistrust of merchants invariably rouses the suspicion that the alloy must be of lead. Clearly, in India eeyam has acquired a further range of meaning, referring to pure lead, pure tin, and unspecified lead-tin alloys.

Maha eeyam confusion

Although it appears likely that at least a generation or two of eeya chombus must have been some grade of pewter, the strong association of eeyam with lead along with all the meanings attached to “eeyam” has precipitated massive confusion–and considerable hilarity.

In this community thread alone, one sees it all play out. There are those seeking to establish the value of trace amounts of lead for the human body, and specific data on maladies reported (a quest later abandoned when it appears clear that the eeyam in question is tin). Some still try to redeem the value of lead on historical cultural grounds: the “we’ve been drinking eeya chombu rasam for 100 years!” logic. Others point to the science of lead toxicity and quote the Atharva Veda, no less, to jolt eeya-rasa-bhaktas out of their cultural entrenchments: when “craving increases beyond a limit, sane thinking disappears.” Eeya chombu rasam is then singled out as the culprit responsible for our grandmothers’ chronic anemia, because “Lead peacefully enters the bone-marrow and remains there for life-time” causing chronic toxicity. [Sidenote: at least one study confirms that female workers in lead-related manufacturing are “more vulnerable for lead-related anemia than male.” Source: Hsieh et al. 2017]

Then there are others who try to explain the science behind eeya chombu rasam’s distinctly different taste using beer-and-coke analogies: lead has higher electro-voltaic potential (why it’s used in batteries and voltaic cells), so consuming acidic foods from such vessels would generate “‘electric voltage,’ which tickles our taste buds…That’s why ‘Budweiser in tin-can tastes better than one in bottles’…Same is with Coke cans..” Still others liken the consumption of eeya chombu rasam with cigarette smoking, alcohol, and eating red meat: you know it’s bad for you, but it tastes so darned good you do it anyway. Some say that chombus were always lead; tin was only the kalai or lining of brass cookware… and on and on, digression upon digression, much to the chagrin of the person who started this unfortunate-but-incredibly-revealing thread.

But on the specifics of which rasam is best prepared in the eeya chombu, or whether rasam should ever be stored in the chombu–or how long it should be allowed to remain in the vessel–at least this group of mostly men wax nostalgic but remain silent. Only one makes reference to pewter at all, and he is ignored.

Modern e-commerce sites like Zishta, riding the wave of the heritage cookware craze, too, make the fundamental assumption that older vessels were lead which becomes the root cause of modern anxieties. So they release videos demonstrating how to tell pure tin vessels apart from lead with scratch tests in an effort to demonstrate the authenticity of their product. If competitors’ vessels are pewter, however, and a better grade of pewter at that, these scratch tests would be unlikely to demonstrate anything. We would have about as much reason to trust Zishta (making the very dubious claim that there are but “2 artisans remaining who beat pure tin by hand for 8 hours to make one vessel“) as the Kumbakkonam merchant sourcing from a long line of local craftsmen.

The magic of the eeya chombu

Only one single truth remains stable through all these many contortions: eeya chombu rasam tastes absolutely great. What explains that?

A contributor to the same Tamil Brahmin forum discussed above offers this chemistry of taste explanation: “Lead salts especially acetate(ex-Vinegar,)-Tartrate(ex Tamrind=puli) is very “Sweet” and the Sodium-Potasium Tartrate chealates with Pb(Eeyam) and the volatile oils in Tamrind, Jeerakam, Milagu are trapped in the matrix–so Eeya Chombu Rasam is sweet and tasty.”

Possible–if eeya chombus are, in fact, made of lead. Even if eeya chombus are historically low-grade pewter, however, we need an explanation that is focused on tin.

Here is where I should pause and wax eloquent about how tin (vanga, in Sanskrit) has been used in Ayurveda/Siddha practice and good for the body in some straightforward way that has since been upheld by western science. But this hasn’t happened yet. As I see it just now, there are two lines of thinking here, and they’re in agreement on taste and precaution, but not (yet) on therapeutic value.

Ayurvedic texts recognize the curative value of metal therapies, largely via the use of bhasmas: unique Ayurvedic organometallic preparations used for medicinal purposes. The bhasma preparation process is long, involves multiple stages of “shodhan (purification/ detoxification), jaran (heating and stirring), bhavan (levigation) and maran (incineration)” with the aid of specific media, including herbs. Each step must be meticulously undertaken so as to reduce drug toxicities. Vanga bhasma or bhasma made of tin has been long known to have widespread applications, “used in the treatment of genitourinary disorder [sic], diabetes, anemia, asthma gastric ulcers and urinary diseases” [Source: Kale and Rajurkar, 2019; Jani et. al. 2009].

Vanga bhasma of course deserves posts all its own; here what matters is only that tin is known to Ayurvedic medicine for its utility–but in carefully prepared form and as what we would call now nanotherapy. The only question is whether eeya chombu rasam, although an entirely different preparation, is also drawing on the therapeutic properties of tin, which it might be, or if it’s simply a matter of taste, which it undoubtedly is.

The science jury’s honestly out on therapeutic properties. The US Center for Disease Control’s “Public health statement on tin” does not find any evidence that tin is a necessary element for humans, but admits apparently very agnostically that it exists in the soil and therefore will exist in food. [But see Heinz Rüdel on bioavailability of tin compounds here.] Cautions seem to abound, drawn from long experience of using tin linings for canned food–but they all treat tin as a barrier, the breaching of which can introduce other ions, not of tin but perhaps copper or iron. The same cautions abound in India, too, where the practice of re-tinning particularly brass vessels is hundreds of years old and a necessary expense (a fact of which many a crafty craftsman has undoubtedly taken advantage).

Tin itself, however, is not inert, it’s just slow to react. The risk with tin-lined canned foods is that headspace gasses at the top of the can (if the sealing is not done well enough) can cause some amount of tin to be incorporated into the contents as stannous oxide while the can sits on shelves; this may cause stomach aches and loose bowels. Hence also the common warning about not storing foods in the same cans after they have been opened. Elemental tin does react with acidic contents, especially if left for several hours, and we know at least from some rat studies that this reduces the concentration of other trace elements in the body [Source]. So: it takes time, but it does react, and that’s not without impact.

This, at last, comes close to explaining a few things about eeya chombu rasam–why some (primarily tamarind-based) rasams are favored in the eeya chombu over others; why eeya chombu rasam stored in the chombu tastes even better the next day–but why such storage practices are generally frowned upon; and possibly even why the process of making rasam in eeya chombus involves first simmering the acidic ingredients (tomato, tamarind), but in general not elongating the cooking process into endless boiling, which kills the fine balance of tastes as much as it fosters other unwanted reactions.

Very interestingly, many contributors to this Food52 forum remark, over and over, about the improved flavor of food cooked in tin-lined copper pans, even though stainless steel is hardier and less expensive. And this contributor to a Stack Exchange conversation on tinware toxicity answers his own question: “why is a fragile glass pot the preferred vessel [over tin cans] for preparing coffee?” thus: “Perhaps a difference that can be even tasted.“

Perhaps, indeed. & the taste not-desired in coffee is the very one that adds that unmistakable je ne sais quoi to rasam.

In the end, here’s what you need to know…

& some things worth thinking about, before you jump on the latest heritage cookware fad-trend-whatever:

1. The eeya chombu (your grandmother’s or the modern ones) is very likely not lead, but some form of pewter or possibly pure tin. Note there is no way to verify if it’s pure tin and not an alloy; see point #8 below. Older pewter has lead; if it has darkened and dulled with use, it’s best discarded. Higher grades of pewter should be lead-free, mostly tin, should retain their sheen, and thus are fine for cooking use.
2. Not all rasam tastes are transformed equally by the eeya chombu. Tamarind-based tomato, pepper, jeera and allied rasams likely benefit most from being made in eeyam vessels than others. Citrus reacts with tin, too, but citrus souring agents are typically added at the end for nutritional reasons, so there’s no distinct taste advantage in making those in eeya chombus. & my vazhaithandu mor-rasam really needn’t have been made in an eeya chombu at all.
3. Do not store your rasam in the same eeya chombu you used to prepare it. So that the eeya chombu rani can make an appearance on your table, storing it till lunchtime is likely ok, but longer storage times can increase toxicities. On the off-chance that there’s some lead impurity in your chombu, less time in the pot is safer, too.
4. Simmer, simmer, simmer–don’t boil!! Tin has a low melting point, so your vessel should always be 3/4 full, and your flame on medium-low unless you want a meltdown (literally). Besides, rasam is never brought to a rolling, roaring boil. The right dal and sour-spice quotients cause it to froth and rise even at a simmer–then you season, and done. See the marunthu rasam image below. Aim to get that combination just right, but please do not bring eeya chombu rasams to a great big boil, and then add disclaimers that this is not “authentic rasam,” it’s just your recipe–because at that point it’s not rasam at all. It’s a mere soup, and there is a difference.
5. You do not need to buy an eeya chombu to make fantastic rasam. Heard? I’ll say it again: you do not need to buy an eeya chombu to make fantastic rasam! If you know the story of stone soup, you’ll know also that it’s not the pot nor the stone that makes the soup. It’s not even the rasam podi you use, dare I say. The real magic of rasam is ultimately in your hands, your kai gunam: knowing how to coax out those distinct flavors and make the right ones stand out, knowing the proportions that create that perfect foamy rise, knowing how to transform tamarind water and a bit of spice and seasoning into the best thelivu rasam (with no residue or rasa vandi), how to work with new tastes or even poor ingredients, when to add what spice or what mel podi (“powder on top”), and so on. I struggled with getting rasams right for years, only acquired my first eeya chombus in 2020, and even in those I botch rasams from time to time. My ultimate trick is in teaching myself to be quiet and attentive while making rasams, which then turn out magnificently—eeya chombu or no.
6. If you are hell bent on buying a eeya paathiram, please spend some time identifying the right sources. There are any number of people around Kumbakkonam and beyond selling eeya vessels, and they are not just craftsmen or merchants any more but caretakers of our collective metallurgical and culinary heritage. There’ll be better ones and poorer ones, as with any such trade. But when Zishta steps in as the suave middleman to rule them all, please don’t just think about how they can deliver to Dubai with great customer service–but evaluate their claims critically. What are they doing really to help preserve the craft traditions from which they are benefiting so handsomely? How can they possibly claim that there are “only 2 artisans remaining who beat pure tin by hand for 8 hours to make one vessel” when we know there are certainly more? Outrageous!
7. I found my very best source through Anjali Koli’s thoughtful blogpost on Eeya Chombus, thanks to a commenter who left this information: “There is a shop keeper (Venugopal – +91 9445155520) in T. Nagar, Chennai who sells this vessel for almost 40 years now. The shops name is VGS Kumbakonam eeya pathira kadai, near Shiva Vishnu Temple. Its a very small shop but authentic. We bought the vessel and we are happy now as they have options to sell vessel only with making charge if your old material is given.” There are other sources on that comment thread, too. Find them on Anjali’s post. This eeya kadai kaaran who does his business on a dabba phone which hardly gets a proper signal came home, befriended my parents, and managed to get me my chombus at the height of the 2020 lockdowns, returning the Rs.10 I’d overpaid. Buying from sources such as these is not as convenient as online ordering, but does a lot more than support a business: it revives and sustains a lot of the old-world relationships that come alongside. [Side learning: get off Instagram, go read blogs instead].
8. Ask, ask, ask all the questions you want. Is it only vellai eeyam (“white lead,” or tin) used? Certainly make sure there’s no karu eeyam mixed. You can do scratch tests if you like (if the scratch mark darkens, there’s lead within) but those are not going to work to tell pure tin apart from a lead-free or low-lead-based pewter.
9. That said, higher grade pewters should be lead-free & are probably as good as any claiming to be pure tin, and if buying those is supporting the local craft rather than just the middlemen, then what do you have to lose?

Some sources cited in this long-long post, for my future reference and those interested!

• Somobrata Acharya, “Lead between the lines,” Nature Chemistry vol. 5, 2013: 894.
• Kamar Shah Ariffin, “Sediment Hosted Primary Tin Deposit Associated with Biotite Granite and Fault Zone at Gunung Paku, Klian Intan, Upper Perak, Malaysia,” Resource Geology 59 (3): 282–294
• Parashuram Krishna Gode, “History of tin coating and metallic utensils in India (Between A.D. 1300 and 1900),” in STUDIES IN INDIAN CULTURAL HISTORY Vol. III/ P.K.Gode Studies–Vol. VI, Poona: BOR Institute, 1969: 113-117
• Jalpa H. Jani et. al., “The Role of Media in the Preparation of Vanga Bhasma.” AYU 30(2, April-June) 2009: 211-216
• Babita Kale and Nilima Rajurkar, “Synthesis and characterization of Vanga bhasma.” Journal of Ayurveda and Integrative Medicine 10 (2019): 111-118
• Hsieh et al. “Anemia risk in relation to lead exposure in lead-related manufacturing.” BMC Public Health (2017) 17:389
• Hideo Yamada, “The origins of British colonization of Malaya with special reference to its tin,” The Developing Economies, Institute of Developing Economies (1971): 225-245.