Hot-Stone Boiling Maple Sap to Syrup: Theory, Basis, & Public Demonstrations
Originally published on Yahoo! Voices in August of 2012, with an added update in January of 2014 - authored by J. Diemer-Eaton for WIEP.
A recent article featuring a researcher-educator (I highly respect) and his opinion on the plausibility of hot-stone evaporation of maple sap has led to a few messages in my e-mail box, as well as inquiries on the use of deer antlers in transporting hot stones (unrelated to the article - rising from observations of many parks and nature centers' demonstrations of hot-stone boiling maple sap), asking me and Woodland Indian Educational Programs, where we stand on these issues. What follows is our answer to complicated question that has no easy answers.
I have seen a trend for nature centers and maple syrup festivals to feature "Native American maple sugaring" demonstrations that only highlight hot-stone boiling, alongside of pioneer maple sugaring demos that feature iron kettles evaporation.
Considering that most of what we know about past Native American maple sugaring is of the post-historic peoples, when most (if not all) were utilizing trade metal kettles in their sugar camps, this picture painted by solely associating stone-boiling sugaring with Native Americans really serves to highlight what contemporary people consider to be "primitive." This demonstration, without demonstration or at least discussion of other evaporation methods, does lean more towards just an entertaining performance at the expense of education, and of Native Americans.
Right: Simmering maple sap/syrup in cast iron kettles over a fire (at the National Maple Syrup Festival, IN, 2010).
And So They Question Hot-Stone Cooking as a Native American Technology "Their method of cooking is so new, that for strangeness I desire to speak of it; thus it may be seen and remarked how curious and diversified are the contrivances and ingenuity of the human family… they fill the half of a large calabash with water, and throw on the fire many stones… When hot, they are taken up with tongs of sticks and dropped into the calabash, until the water in it boils from the fervor of the stones (1)."
We can't deny the practice of hot-stone boiling, and other methods of cooking with stone, nor would we want to. It is truly an effective method of cooking foods. It is just one cooking method utilized, much rarely in the southern Northeastern Cultural Area, and utilized more frequently in the northern reaches of the same region. The reasoning for this regional difference, some scholars insist, may be because of the extensive use of earthenware cooking vessels in most of the region, which would reduce the need of hot-stone boiling to possibly limited scenarios: hunters/traders on-the-trail small scale cooking, large gatherings where troughs (possibly old dugout canoes) with larger holding capacities were filled with soups and hot-stone boiled, possibly used in conjunction with pottery and later metal kettles so large amounts of sap could be reduced efficiently.
The Real Question Is: Was Hot-Stone Boiling Employed in Syrup Production? "Wherefore then should [the Master of Life] have withheld from us the art of excavating the trees in order to make troughs of them, of placing the sap in these, of heating the stones and throwing them into the sap so as to cause it to boil, and by this means reducing it to sugar? (2)" -Kickapoo Man ca. 1825.
The above quote is very interesting for a few reasons. To start with, it was part of a Kickapoo man's response (ca. 1825) to the "trend" of white society questioning the Native origin of the sugar - insisting a different history where Europeans taught Native Americans how to tap trees and make syrup. But his response, specifically his alluding to hot-stone boiling, is at one point trustworthy, but at the same time problematic. It is encouraging because stone-boiling truly is a Native American cooking method (in comparison to the European newcomers), and although he and his community utilize metal kettles, and have been doing so up to two centuries, he doesn't cite kettle evaporation. On the other hand, he does say the "of heating the stones and throwing them into the sap,… and by this means reducing it to sugar" and there exists uncertainty as to whether or not hot-stone boiling could actually reduce the sap to dry sugar. Many who have tried it in modern times have only produced burned, sludge-like syrup-sugar that sticks to the stones; it is a far cry from the fine maple sugar the Native Peoples produced in metal kettles and presumably in earthenware vessels before. And not that we would rely on the tries of modern folks alone for such a conclusion, but there does exist an inherent problem of keeping the vat of sugar hot enough while not burning the sugar in direct contact with the hot stone, which seems to be a scientific impossibility. If this was done, we are missing a key understanding of method (such as a buffer). This might question the accuracy of this comment, but it seems the man who said it believes it. Certainly, the concept of hot-stone boiling to make maple sugar is, as some feel, a modern "myth." Still because of other possible minor details, including choice of terminology, we can't read too much into this statement one way or the other, with one exception: his comment dates the popular belief of the Native American practice of hot-stone boiling sap to sugar at least back to 1825.
Hot maple sugar, ready to be processed into dry sugar (LM Sugarbush, IN, 2009).
Jessica paddles hot sugar as it cools to granulate it (Prophetstown State Park, IN, 2010).
Taking Finished Sugar Out of the Equation "They were satisfied with giving it two or three boilings, in order to thicken it a little, and to make a kind of syrup from it, which is pleasant enough (3)."
Earlier European observations of Native American maple sugaring didn't actually refer sugar at all, but instead made mention of the Native People's limited boiling practices to make a light or medium thick syrup. When hard sugar is taken out of the equation, hot-stone boiling seems more plausible in the process. Keeping on to that idea, even when hard sugar was produced (such observations come trickling in from the early to mid 18th century and on), evaporation was still a necessary part of the process. It is more than likely that if stone-boiling was a part of the sugar-making process, it was employed as only one of a few methods.
What Would The FDA Say? On the same note, they also consumed small amounts of ash with everyday meals. Some meats were cooked on coals, which try as they may to use "clean coals," little amounts of ash will find its way to cling to the food. Actually, Heckewelder notes some Delaware had made fun of white folks who also cooked their meat directly on hot coals, claiming they don't even make an area of clean coals to cook on but are satisfied to have meat caked with ashes. Be as it may, the Native Peoples did enjoy a little ash on their foods; certainly corn cakes baked on hot rocks (among other foods) picked up ash, and good flavor. Not to mention that cooking over a fire, even in uncovered kettles, also attracts trace amounts of ashes to land in the food. And those familiar with open-fire cooking might also point out that sometimes enough light, white ashes float into their stews to help give it a flavoring unachievable on their kitchen ranges. Taking that into consideration with the fact that evaporating sap was done uncovered, little amounts of ash did find its way to the sap regardless. It is actually something I did note when we started making maple sugar. With this in mind, we can take another look at hot-stone boiling.
To be sure, the issue is not with minor accumulation of ashes in the syrup, but with enough ash buildup to render the product inedible. The resulting alkali is not only far from sweet, but can be very harmful if consumed. So the question remains, is hot-stone boiling impossible when it comes to rendering an edible and pleasant tasting maple syrup or sugar (as only one part/step of the process)?
According to one educational organization it is. They concluded that when attempting to stone boil sap to syrup, the build up of the ash made the syrup inedible. I have no doubt this is true, and I have seen much many demonstrations of such result in less than appetizing thick sap and syrup. The people who many times claim this to be the Native American way will not try to eat what they have made, which should have a few scratching their heads (indeed, this article is the result of such questions posed to us even by some demonstrators and event coordinators - so no, you are not alone). However, this is not always the case, and the exceptions to what the majority have experienced could be jumping off points to understanding what cooking methods were plausible in evaporating sap in a pre to post contact Native America.
The Affect of About 40 Hot Stones in a Batch of Maple Sugar: What We Know For Sure One hot-stone boiling demonstrator, who we will refer to as Mr. P, has demonstrating hot-stone boiling maple sap for over twenty years, and it is courtesy of Mr. P we have an example with a little more of a sweet ending:
Mr. P hot-stone boiled sap from the half and half point (sap obtained from a reverse osmosis machine) to syrup in three boilings throughout the day (just for demonstrations). He used about 12-15 hot rocks to bring the sap up to a rapid boil during each session. By the end of the day, after only 3 boilings totaling about 36-45 hot stones used, Mr. P had produced syrup, which he offered to us (WIEP). We refrigerated it to save for the next demonstration weekend. The maple syrup was not only quite good, but we made sugar of it over the fire (in a tin-lined brass kettle). Our audience helped themselves to trying the sugar, and my husband and I enjoyed it just as much as they did. We didn't even taste a difference, let alone be unable to eat.
No, this is not an example of hot-stone boiling from start (fresh sap) to end (syrup), but an example from the midway point (more or less) to syrup. Another thing to keep in mind is that up to 45 hot rocks were dropped in this batch, none of them cleaned of ash residue, and still the product produced with almost four dozen stones being plunged into it, was quite good and far from inedible - this gives us the knowledge that 40 or so hot stones doesn't give a batch of sap/syrup/sugar an alkali content rendering it unfit to consume (half the boiling process to make syrup). And yes, you read that right… I did mention cleaning the hot rocks, and that's where I'm going next.
A Quick Dunk Have you ever been to that backyard pool where the hosts insisted on putting a tray of water next to the ladder, so you had to step into it before getting into the pool, or maybe you are that pool owner? The objective is to rinse away most of the grass and dirt from the swimmers feet (especially the kiddies) before it contaminates the pool, and causes somebody extra time with the skimmer. It's a simple concept, and pretty effective (more or less effective on children).
For people who know the effects of alkali, such as the Native Peoples who utilized ash lye to "take the bitterness" out of acorns (while leaching) and burn the hulls of corn to make hominy, they certainly weren't oblivious to the affects of large amount of ashes in foods. Taking steps to prevent such contamination is not far fetched for intelligent people who transformed their foods to suite their tastes and diets. When we (WIEP) demonstrate hot-stone boiling of maple sap, we do rinse the hot-stone in a container of water after they are taken from the fire and before they are placed in the sap. We do not have any direct observation of such to go on, however, that really doesn't matter because:
1) Observations tend to only highlight the basic steps and can even be vague. Such as many house building exercises which tend to simply state "they made a lattice of branches to create the frame" which really translates to many saplings, most likely stripped of bark, sometimes fire-harden the ends, and before such poles are just "put in the ground," the post hole cavity had to be created first, most likely with a stake pounding in the earth to mold the cavity before the pole was thrust in, not to mention securing the "lattice work" or crossing poles with cordage made of tree bark (a whole other process). Many details that make sense of historic observation are revealed through archaeological excavations and modern attempts to recreate such processes (see 3).
2) Many observations like to focus more on the "strangeness" of an activity rather than details that Europeans might consider universal or "common sense." Rinsing the dirt off of an utensil before touching food may not be considered "worth the words" of the observer in his/her journal or notes, not to mention many spoke of their experience afterwords, when a witness's mind can recollect less mundane details but spotlight the more "sensational" of the events observed.
3) Almost every historical technology needs to be tested beyond the observations, which usually leaves out some vital information. "Primitive" or ancient technologists and archaeologists (as well as some other experts and scholars) attempt to recreate past processes in order to gain a better understanding of methods and results. Flintknapping is the most common and recognized activity of some ancient technologists (keep in mind that ancient technologists have much more far-reaching focuses than stone tools such as cordage, clothing, housing, wooden implements, dyes, earthenware, even foods). Such tests that use only time-period methods and materials are referred to as experimental archaeology. There has been a misuse of this term as of late, it being used incorrectly to describe any activities related to recreating the past, from uncommitted hot-stone boiling demos to weekend camping at re-enactments. To be clear, most public demonstrations of Native American maple sugaring is not experimental archaeology.
Keep in mind what direct observations we have are boiling stews and soups, and not maple sap. When heating a gallon or so of soup, cleaning rocks of ash was not necessary because 1) only a few hot rocks were necessary to heat the soup, so the ash content could not build up to harmful levels, and 2) some ash does flavor the soup in a pleasant manner. Even if most (if not all) maple sugar producing Native communities didn't choose to add salt (quarried or saltwater salt) to their foods, they did like the "salty" flavoring imparted on their meals through hot-stone cooking and coal grilling.
Mark of WIEP dunks hot stones in water (to wash of ash) before placing in maple sap (photo from newspaper, WIEP at National Maple Syrup Festival, IN, 2009).
Let's Talk Technique For those spectators used to seeing hot-stone boiling demonstrations, ours is usually met with the "ah ha" moment; suddenly the plausibility and practicality becomes clearer as soon as we grab the hot rocks with our wooden tongs, made for the job. Many others struggle to grip and instead juggle their hot rocks in a precariously manner on unmodified sticks or deer antlers, dropping the stones in the dirt before putting them in the sap. And most methods demonstrated rely on two implements to grab the rocks, one per hand. Trapping and squeezing a hot stone between two ordinary sticks, each stick controlled by one hand, usually allows for minimal control over the rock. The best control I have seen with unmodified utensils for picking up the stones was by the man we cited earlier, Mr. P:
Using two forked sticks (natural, unmodified other than cut), he traps hot stones in the fire as if spearing a fish. Truly, his method of grabbing a hot stone looks less like picking up a rock and more like hunting a small critter, but his force and fast movements rarely fails to grip and bring forth a stone. His rock successfully cornered, he tightens his grip of his forked sticks on the stone raises it from the coals. The hold he created by angling his sticks just right works for a surprising graceful transport of the stone from the fire to the sap. Mr. P had a good amount of control over the rock, and consequently, dropped stones much less than others using the same implements. His skill also translated to speed, being able to move two hot stones in under ten seconds, and in no clumsy manner as might be seen even among survivalist stars on cable television. Although he does not take the time to clean the stones of ash, he does insist (to his audience) it was a step worth taking. He also points to the pioneer maple sugaring camp (about 30 feet away), and cites the rapid boiling he created by very hot stones as evaporating the water content faster than the sap boiling in iron kettles hung over a fire. It is with his proficiency we can have a realistic perspective of how skill and unmodified implements combined to equal a successful cooking technique, however, while his control is impressive and I could certainly go on with praise, there are some major glitches and technical factors that need to be addressed here too.
To start with, the granite stones Mr. P employs are cube-shaped and not weathered. It is thought that the stones used by the Native Peoples for such cooking were found and not quarried (chiseled or cut out of), and most likely worn by the environment into more spherical shapes with blunt edges. It becomes very clear that a big part of Mr. P's control over the hot stones using only forked sticks relies heavily on the stone's protrusions and well-defined angles.
Another example Mr. P's demonstration falls short of a real world maple sugaring scenarios has to do with his fire. Because he runs only two to three demos a day, he burns down and removes any flaming wood from the fire pit before taking his stones out. By doing this, it allows him to approach the stone-filled coal pile on any side, and put himself directly over it while extracting stones without smoke in his eyes, and very little smoke to burn his lungs. Obviously, burning down the fire or breaking it apart makes it easier and faster to grip the stones, however, in evaporating maple sap, it is most important to keep the fires running because sap will not evaporate enough with only one round of hot stones. Most likely the fires where kept burning, whether rotating the live fire to different sides of the pit, and/or raking the stones out from beneath the burning fire. This means a little more time devoted to rounding up rocks while a fair amount of smoke presents an obstacle to both breathing and sight, which Mr. P's method of stone-boiling does not fully address.
Another Tool For the Job The above two may be considerations to keep in mind when discussing Mr. P's success in hot-stone boiling, but it is not a factor in our (WIEP) demonstrations. We use weathered river rock and keep our fires burning while extruding the hot stones. While Mr. P and the majority of demonstrators use a two-stick method, we use one wooden tong to grab a hold of the hot stones. The tong is made of one stick (we use hickory many times for this), about three feet long, and split about two-thirds the length to create the tong. With this tool we can squeeze the stone with such force that it allows us to add a vital step into the hot-stone boiling process - cleaning much of the ashes off the stone.
When using both hands to control separate utensils that traps and squeezes the rock, the demonstrator cannot alter their arm movement while transporting the stone from the coals to the sap. To do so can compromise the grip on the stone. Keep in mind this precarious method of griping and balancing the stones in between two unfixed utensils may inhibit what might be a necessary step - reducing ash residue on the stones before applying to the sap. It is almost certain, as Vosteen points out, that hot-stone boiling the sap for so long will result in too much alkali, causing the sap/syrup to be inedible. Indeed, I have told by a few demonstrators that they would not drink the thick sap or syrup they produced with hot-stone boiling. One naturalist admitted that his hot-stone boiling demo use water instead of sap in order not to "waste" good sap. The same person pointed out that what he produces with hot-stone boiling is filthy, yet he teaches that this method was employed by Native Americans in making syrup/sugar, and with good reason, questions whether this is true.
Assuming that rinsing the stone before putting it into the sap was necessary, it would have been a little more awkward to do with two, unattached sticks - though certainly not impossible. For those with the skill, it may have been a minimal issue. They "scoop" up the stone, using one stick to push the stone into the fork of the other stick, and careful but almost effortlessly, carry the hot rock and lower it into a quick water bath before transferring it to the sap.
However, the two-stick method has at least two shortcomings when compared to a single tong - cleaning the rock before putting it in the sap, and the ability to use larger, heavier rocks for larger vats of sap.
Sap boiling by hot-stone within, in a wooden trough (WIEP at Sugar Camp Days at Bendix Woods Park, IN, 2014)
Don't "Knock" Our Tongs Our ability to knock the ashes off the stone before rinsing keeps even a large amount of ashes out of our rinse water (and therefore our sap too). Our grip with the tongs are tight on the stones, and with each rock we drag out of the ashes, we give it a quick thump on a hard surface, resulting in most of the ash residue to fall away before we dunk it into water. A simple action like this may be overlooked in our understanding of hot-stone boiling maple sap. Note: the photo above shows a hot stone going into the sugar-water uncleaned.
Size Might Just Matter The size of the stone may also be a critical factor in the efficiency and plausibility of hot-stone boiling in the maple sugaring process. I have witnessed demonstrators using what I believe to be rocks too small for the vat of sap they wish to boil. Such miscalculations can lead to wasted energy and inadequate results. Larger rocks store heat that can be dispersed for a more extended length of time while in the sap.
For those picking up and transporting their hot stones with two, unattached sticks, they may not have the ability to use larger rocks with ease. The heavier the rock, the harder it was to control and not drop. This is because the weight and balance relies much on the operator's wrists. The wrists must both keep steady while supporting weight extended past the fingers - this is a precarious method on the body to hold and transport a load. In using our tongs, the weight is secured with the clasping hand, and lifted with the bicep. Both actions are usual to the anatomy assigned to each action (naturally strong), and both actions are easily executed at the same time.
Right: Mark of WIEP stone-boiling sap - notice all the ash washed off the hot stones in the trough to the right (at Sugar Camp Days at Bendix Woods Park, IN, 2014).
Not All Hot Stones Are Created Equal In using one granite stone with a 4-5" diameter and 1.5" thickness, we are able to keep 1.5 - 2 gallons of maple sap boiling for eight to ten minutes before it is time to replace it with a new stone from the fire (after the sap is initially brought up to the boiling point). Stones must be hot enough to make hot-stone boiling efficient, and anything less than one hour in hot coals (about two hours after starting the fire) is probably inadequate. It is not a figure of speech when referring to getting the stones "red hot." We have never passed up an opportunity during an evening or indoor (inside a longhouse/council house) demonstration to show the audience the very slight "glow" our granite stones emit (some more, some less). This is the level of heat we use in hot-stone boiling, and we consider to be efficient. The reaction from the water when the hot rocks are lowered in can be so dramatic, it is obvious the water cannot move out of the way of the rock's heat fast enough.
I believe that many of the demonstrations I have seen do not heat their rocks to a proper temperature. One cited his observations of his hot-stone cooking versus his kettle cooking experiment, stating that the vessel cooking over/on the fire was faster in evaporation than hot-stone cooking. This is a red flag that makes me question the experiment, believing the hot stone cooking was not conducted with sufficiently heated stones. When done properly, there is no question to the efficiency of hot-stone boiling when compared to over the fire kettle boiling. Not only does it evaporate more water in less time, but it even heats up the same volume of sap quicker than being placed over the fire. Keep in mind that transferring heat directly into the sap via the stone wastes less energy (heat) - putting more heat directly into the sap from the heat source (hot stone), whereas so much energy (heat) is lost when the sap is placed over the heat source (fire).
General factors leading to stones not being heated to a high enough temperature has to do with duration of the stones in hot coals and the temperature of the hot coals (related to type of wood burned and size of fire). Small cooking size fires, big enough to place just one pot over is too small to heat, say 20 or more stones; yet many demos I see use small fires with small stones to boil large vats of sap. The size of the fire's interior, stone mass, and volume of sap are not consistent as they should be.
Historic cooking fires had to be large enough to accommodate a few kettles of sap overhead. This also gives the fire the necessary interior space to build up to 1200 degrees. The fires were run as hot as possible, day after day, and on occasion all night. This makes for a super hot fire pit, and if using the same fire to heat the stones, the stones too became super hot in the glowing white coals.
Sap steam from stone-boiling - notice the ashy water in cleaning trough next to it (Sugar Camp Days at Bendix Woods, IN, 2015).
Foamy hot sap boiling from hot stones placed within (Sugar Camp Days at Bendix Woods, IN, 2015).
Rocks Hot Enough To Start a Fire Even in our limited 6-8 hour shifts of hot-stone cooking demonstrations (boiling, grilling, baking), the high heat taken in by the rock, and its ability to store such heat, has almost put us in "hot water." In one example, we soaked the pit with an estimated 7 gallons of water and other liquids (we empty a lot of troughs and kettles at the end of our day), and left our demonstration camp to get dinner. Upon returning 3 hours later, we decided to start the fire again for evening light and heat. My husband took some dry grass in his hand and placed it on the stones in the middle of the pit (the stones that were soaks just a few hours previously). He expected to use a lighter to start the tinder, in just a few seconds, the bundle of grass began to smoke, and with some barely any extra oxygen it caught fire. The stone holding the grass bundle succeeded in starting a fire after being drowned in gallons of water 3 hours earlier!
Oh, Yeah… And A Sudden Deer Antler Trend In the same spirit nature centers, arboretums, syrup festivals, and state/national parks have jumped on the "hot-stone boiling defined Native American maple sugaring" bandwagon, they have also spread the idea that the Native People (Late Woodland tribes) used deer antlers to pick up the hot stones. I am so far unable to locate the evidence or observations of such. Of course, that doesn't mean there isn't any, and I will continue asking around and researching this issue. Most likely this idea comes from at least one observation, maybe from outside the Woodlands. There is obvious issues associated using deer antlers to pick up hot stone that must be addressed.
First, I see demonstrators use only the antlers with no modification, putting the operators' hands far too close to the fire, boiling water, and the hot stone. The heat emitting from the coals, and the steam released from the boiling sap should be so hot that hands using short antlers to transport hot stones would be burned with every round. You shouldn't be able to place your fingers within a foot of the coals for more than two seconds (even along the perimeter of the fire), and if you can, than your fire is not hot enough. Just recently, I demonstrated hot-stone boiling on a small scale (about a quart of sap in a birch bark vessel with 3" diameter basalt stones). Unable to mail my usual wooden tongs from my mid-west home to the east coast (over 3 feet in length), I instead used metal salad tongs about a foot in length. Even on a small scale (with a smaller fire), my fingers took a brutal beating. It would be ridiculous to believe that the Native People would subject themselves to such punishment when just using correct utensils would remedy the situation.
Using such short implements forces the operator to put their face much closer to the fire, risking their hair and skin to burning, and their eyes to sparks. Sure a demonstrator could use a stick or paddle to roll the stone well outside the perimeter of the fire, but it needlessly complicates and lengthens the process. It is more time efficient and manageable to use the correct tool to pick the stone up from the ashes, rather than push it clear of the fire and switch tools as quickly as possible to pick it up (hot stones outside the fire pit area begin to lose their heat more rapidly than stones waiting in the coals or hot ashes). And while I haven't seen any demo do it yet, one could extend the reach of the antlers by adding on a pole, however, most likely in doing so the operator looses even more of his/her ability to control the stones.
Three other issues in using deer antlers come from material comparison: antler versus wood. 1) Antlers tend to be slicker and afford less grip than wood. 2) Antlers, as a material, are prone to burn, and when they do they emit a foul odor. And most importantly, 3) wood is much more common in the Woodlands, and the people utilized wood much more than bone (and stone) to make their tools and utensils. I do have a sneaky suspicion that the idea of using antlers may have been taken from archaeologists' recreations of paleo and archaic life-ways - and while bone tools may have been the all purpose material for such time periods, it was wood that was the most common resource utilized for tools by the Woodland Indian Peoples.
I realize certain things seem "stereotypically expected" to the audience, and using deer antlers is sure more noteworthy to the audience, but the question is are we more entertainment or more educational. Our jobs as presenters and demonstrators are both in the realm of educational outreach and tourism. Our drive to please our audiences can not guide the content of our program, instead, the cultural facts must be enhanced by our want to create an experience for our museum, park, and festival visitors. Many more mainstream Americans would rather see Plains tepees at northeastern Native American educational sites, but it doesn't mean we should endorse it as a historic native home to areas they weren't built.
Jessica of WIEP makes tacky maple sugar "gum" candy for visitors (at LM Sugarbush, IN, 2015).
The "Caveman Syndrome" in the Realm of Hot-Stone Boiling Maple Sap One particular inquiry asked if I thought that the experiment which concluded hot-stone boiling makes sap/syrup unfit to consume was an example of the "caveman syndrome" - a term I use to define a particular negative attitude in the Native American interpretation and research fields. The "caveman syndrome" defines either 1) a major underestimation of Native ingenuity, based loosely on bias first-hand observations or the attitude "well I tried it and couldn't, so there is no way they could have" and 2) purposely constructing interpretations or exhibits on Native Americans to highlight what we feel is "primitive" while disregarding cultural traits that don't fit the "primitive model."
One particular archaeologist who did some hot-stone maple sugaring experiments over 20 years ago concluded that it was impossible to make hard sugar (finished sugar, not syrup) form stone-boiling. The truth is, this archaeologist has not been proven wrong, yet. With all the evidence and experiments that have been conducted thus far, I must go with this conclusion until new evidence comes to light, which is very possible. This conclusion is not just made with the "we couldn't do it" attitude but is also evident in general priciples of heat exchange: how can we get the whole batch of sugar up to 30 or so degrees over the boiling point without burning the sugar that directly touched the hot stones? Maybe the answer has to do with a buffer, maybe the answer has to do with sacrificing so much sugar in each batch to burning.
Just because a few (and in some cases one) archaeologists (many with limited to no "primitive" skills) and/or "primitive" technologists (usually with the highest skill sets) haven't been successful in doing so doesn't mean it wasn't possible. The two major obstacles they point out is 1) ash accumulation, which I am on the fence about and hope to run a few experiments myself when my health problems subside - not that if I fail does it mean it was impossible, as I will never claim to be as talented as folks who grew up with such skills; and 2) the direct hot rocks burning thick syrup and sugar that touches it, while not heating the whole enough to crystallize the sugar (make hard sugar). I fully agree with these obstacles they have defined. If the latter was accomplished historically (making hard sugar with stone-boiling) than we are certainly missing a huge piece of this puzzle. Maybe down the road it may be figured out, or with time it may be proven impossible beyond a doubt (which will need more time and much more experiments by different folks with different rock types, containers, tongs, skills, and temperatures of stones). I don't believe we are at a place to say "it was impossible to make hard sugar with hot stones" however, the evidence is building against it, and I do not agree that hot-stone boiling wasn't used as part of the sap evaporating process.
It is premature to call it case-closed. Archaeologists and other researchers have always built upon previous work, and many times not just added to it, but contradicted it. One such "conclusion" or "fact" of recent times was that of earthenware pottery being unable to withstand boiling maple sap to sugar - a "truth" scholars repeated blindly to their students and colleagues. All has changed within the last few years. It was the work of ancient technologist Erik Vosteen and his colleagues that disproved old notions of native clay pots "too fragile" for the hot sugaring process (his work can be seen in the YouTube video below). Because of that premature conclusion, almost every book that comments on Native American maple sugaring throws in a blurb stating "their pottery too primitive to withstand the hot nature of the sugar-making process…" and now, most nature center and park demonstrators share that same opinion, which is passed on year after year to their audiences. It is funny to think that I have had more opposition to teaching about the practice of evaporation in earthenware vessels than I have had to hot-stone boiling maple sap.
Below: Video of boiling sap in clay vessals by the Erik Vosteen - his insights and tested applications are vital to our understanding of the possiblity of pottery use for sap reduction, even sugar-making.
Update January 2014: Creating Hard Maple Sugar From Stone-Boiled Syrup
I was finally able to conduct a mini experiment focusing on the possible low/medium-heat dehydration of maple syrup creating hard sugar. Why this experiment? Well, it is often told that hard sugar can only be obtained by high heat induced crystallization, which at this time knowing hot-stone boiling to be inherently flawed for heating such a vat of syrup past a certain thickness evenly (without burning much of the syrup/sugar touching the stones and heating the rest to 35 or so degrees past the boiling point) makes the possibility of making hard sugar using only hot-stone boiling seem impossible. But knowing hot-stone boiling can indeed take sap down to a syrupy stage successfully (ie efficient hot-stone boiling: using good size rocks at a very high temperature, using the correct tools with a certain skill level, and probably cleaning the hot stones with a water dunk before being put into the sap), then the question is, how do we make hard sugar out of syrup without the use of pre-historic earthenware or post-historic metal trade kettles?
The answer lies in a usual Native foodways practice: dehydration. Indeed, you don't need high heat crystallization to make hard maple sugar. For example, birch-bark containers suspended high over fires (for a low to medium heat exposure) can provide the perfect environment for maple syrup to dehydrate and become hard sugar. The bark containers would be lined in oil/grease and the syrup added (not too thick). As the syrup's water content evaporated, it could be "scratched," allowing warm air to touch many areas of the dehydrating sugar evenly. This hastened the dehydration, making it a process that could last for only a few days (also dehydration must be done within an allotted time or the risk of spoilage became a real threat). Another method, taking cues from other practices of Native dehydration, could have been to lay out sheets of birch-bark either on a rack over a fire, or on/near the ground over heated stones.
Dehydrated Maple Sugar (with an oil coating).
When I conducted my little experiment, I used both wooden and birch-bark dishes, both on the mantle (hot-stone) and near the fire (suspended over the fire). I did this to make sure the container material could take the heat without moisture, which is the question when doing such a dehydration method. Indeed they did hold up just fine. One day, I hope to replicate this on a large scale outside, using the correct materials and open fire.With the findings of the small indoor experiment, I am confident that if a Native community chose to conduct hot-stone boiling of maple sap as their only high-heat evaporation process, they would be able to still create dry sugar by including low/medium heat dehydration. This experiment should also serve to debunk the myth that hard sugar was absent in pre-contact times based solely on the lack of metal pots… it is very obvious today that both earthenware pottery and low/medium heat dehydration are very capable of creating hard sugar.
Takeaways For Native American Maple Sugaring Demonstrators:
It is usual in this line of work for "our understanding of history" to evolve. I like to say: history, a series of fixed human events, is actually always changing. What we teach is a perspective of the past, usually based on less facts and more theories. As interpreters, it is our job to evolve our programs and demonstrations as new research emerges.
1) Demonstrations of historic Native American maple sugaring should never define hot-stone boiling as "the one" step or method used, nor the main step. No demonstration is complete without direct evaporation, whether it be in earthenware vessels (pre-/proto-contact) or metal trade kettles (post contact). Just because it is like "pioneer maple sugaring" doesn't make it right to ignore this predominant Native American method of maple sugaring.
2) Hot-stone boiling demonstrations must be done with a certain level of skill. More damage is caused by incorrect or unskillful demonstrations or token attempts than doing no demonstration at all. Such performances serve only to solidify negative perspectives of "primitivism;" it becomes more of an amusing production for the audience at the expense of Native Americans. A poorly executed hot-stone boiling demo communicates people without intelligence or ability to thrive (which is untrue). A well done hot-stone boiling demo communicates ingenuity; we want our audience to be impressed by the resourcefulness of the historic Native Peoples.
3) Do not simplify the technology or processes of the Native Peoples. Doing such simplifies the Native Peoples in the eyes of our audiences. Address how maple sap was processed in a few ways, and most likely, in a combination method. Hot-stone boiling should only be featured when highlighted with over-the-fire evaporation and freezing methods.
4) Be honest with your audience. We don't know everything, so let's never pretend we do. It is a huge myth in our society that we just know everything there is to know about Native American history, probably because so many docents, interpreters, reenactors, demonstrators, etc. act more like "experts" then just teachers.
5) And this may not be completely on the same subject, but please, use proper and positive language. Saying things like "We don't know how they ever figured out to make sugar from sap" sounds like more like "those senseless people sure did luck out" to our audiences. What you want to say (and hopefully what you mean to say) is "We are not completely sure as to what led to the discovery of sugar from sap… many have their tribal histories that speak of the origin of the practice, while scholars certainly have their theories too. The Native communities, like all societies past and present, sought out resources that supported the lifestyle they desired."
Sources of Quotes: (1) Alvar Nunez Cabeca de Vaca, La relacion y comentarios dos jornados qui hizo a las Indias. Valladolid, 1555. (2) William H. Keating, An Expedition to the Source of St. Peter's River. London: Whittaker, 1825. Vol. I, p.114 (3) P.F.X. de Charlevoix, Journal d'un Voyage dans l'Amerique Septentrionnale. Paris: Giffart, 1744. Vol. I, p. 192.
Jessica of WIEP tends kettles of evaporating sap (at the National Maple Syrup Festival, IN, 2010).
Click here to learn more about WIEP's public demonstrations of historical Native-style maple sugaring for museums, nature centers, parks, and syrup festivals. Currently (2017) WIEP demonstrates for 4 weekends (8 days) at 3 locations - one in southern Indiana, one in west-central Indiana, and one in northern Indiana.