At Vermont Evaporator Company, all our hobby maple-sugar-makers feature "baffled" or "continuous flow" pans, because it makes sugaring more efficient, even in the backyard. But why?
You know what a continuous-flow pan is, but do you know why it's better for sugaring than a flat pan?
To address this question, I asked Expert-of-Sorts, Andy Boutin, General Manager of Pellergy, and, conveniently, co-lessor of 157 Pioneer Center, Suite 1. As Andy was moving stuff around our shared warehouse, I shouted questions at him, and he shouted back, pausing every once in a while to draw me a diagram. Here’s how our high-volume conversation went:
Kate: People want to know why continuous-flow evaporators are more efficient than evaporating on a flat pan. I gather the answer lies in understanding a principle of physics called a “gradient.” I’m trying to figure out what a gradient is, what it has to do with sugaring, and how a continuous-flow evaporator exploits that principle to make more syrup in less time. Can you help?
Kate: Wait. What did you study again?
Andy: Marine Engineering and Naval Architecture.
Kate: Hmm. But that involved a lot of Physics classes, right?
Andy: Yes. There’s a lot of fluid dynamics in that education, with ships and man submersibles traveling through water at different densities. It’s relatable.
Kate: Sold! Why is a continuous-flow pan better for sugaring than a flat pan and what does it have to do with the “gradient.” According to Lord Google, gradient is defined as “an increase or decrease in the magnitude of a property (e.g., temperature, pressure, or concentration) observed in passing from one point or moment to another.” What does that have to do with the price of syrup?
Andy: Lord Google is correct, of course, but that's not how I would explain it. Let’s back up.
Gradient is “physics” for as you move through space or time, something that can be measured changes gradually over the course of that distance. So, on a hot summer day, in a house with no internal doors (or doors that are open), if you climb the stairs from the basement to the first floor, the first floor to the second floor, and the second floor to the attic, you travel through a temperature gradient. A gradient is a gentle slope, not a cliff, and is not the result of a physical barrier. So, when, on that same hot summer day, you cross the street and open a door to a nice, cool, air-conditioned house, you are not travelling through a temperature gradient – the change is not gradual and is the result of a physical barrier.
There are a number of gradients at play when sugaring, but probably the most important one for purposes of this discussion is the density gradient that results from changes in sugar concentration as water evaporates and sap turns to syrup.
Kate: OK, I’m with you. Are there density gradients no matter how you sugar?
Andy: Yes. But they don’t operate the same way in every pan. Envision a flat pan the same dimensions as the Sapling Evaporator Pan---20” x 30”---but with no baffles. Think about the pathway from sap to syrup in that pan. Put the sap in. Start the fire. Water boils off. You add more sap. Now you have a density gradient: the denser liquid is at the bottom of the pan and the less-dense liquid is at the top of the pan. Every time you add sap, that density gradient forms (and, by the way, you kill your boil). So you have to keep boiling and boiling until the entire pan is the same density, and then you draw it all off. That’s the batch process. The gradient works against you, not for you, when you batch.
The concentration gradient works FOR you in a continuous-flow pan, both in terms of efficiency and quality. Now take the actual Sapling Evaporator Pan---20” x 30” with two baffles---and what you have is a pan that operates as if it is a 10” x 60” pan, squashed over the firebox. Now: put the sap in, start the fire, water boils off, you add more sap to one end of the pan only, and you’ve rearranged the gradient into a flowing river, where the less dense liquid pushes the denser liquid toward the pour-off, instead of a stagnant pond with muck settling at the bottom.
Kate: That’s quite a visual. Thanks. And there are efficiency gains as well as quality gains, you say?
Andy: Yes. In the flat pan, the gradient is only as long as the pan is deep, with a baffled pan, the gradient is as long as the different channels all stretched out. The efficiency is in the continuous flow that the latter gradient arrangement allows for – there’s no time-killing start and stop to your boil. The quality gains are that when you do draw off, you are able to take off only one density of syrup, even while other densities exist in the pan simultaneously.
Kate: One last question. Is it just me, or when you Google “sugar gradient maple” does the internet try to sell you wigs and quilting fabric?
Andy: Um . . . It’s you.
At the Vermont Evaporator Company, we specialize in manufacturing and selling backyard, no-sugar-shack-required maple-syrup evaporators and evaporator accessories, like the Sapling, pictured above, direct to consumers, online. For the rest of what you'll need this season, we've curated some other online resources for you. Happy shopping!
One of the questions I get the most is "where do I get sugaring supplies?"
The truth is that we have cobbled together a collection of old galvanized buckets and antique spiles from local hardware stores, flea markets and by word-of-mouth for our hobby. Hardly a satisfying response for the budding sugar maker, I'm afraid. Besides which these sources, especially hardware stores, tend to have supplies only seasonally.
Depending on where you live, Craigslist may be a good choice. We have certainly gone there for bigger items like sap storage tanks with success. But again, supplies are likely to be seasonal.
Some of us are lucky enough to live within driving distance of brick-and-mortar maple sugaring supply businesses and have the time and inclination to go there. But, then again, many of us live in the boonies and just don't.
So what's a backyard sugar maker to do? Let's start with the basics. You already have a drill and a 5/16 or 7/16 bit. Right? You have trees. Yes! You need buckets and spiles, sap storage containers, maybe a thermometer and/or hydrometer, filters and maybe some bottles. OK.
I've culled through a number of online resources and here's what I've come up with, in no particular order:
www.sugarbushsupplies.com - This site gets the awards for having abundant useful information and for its range of choices. It has a wide variety of taps at decent prices, and a few different bucket choices as well as sap storage solutions. It has a lot of thermometers, hydrometers and filters to choose from and there's good information and pictures so you can make a good choice on all three. (For example, the catalog explains that a double layer of filtering, including a filter and pre-filter is recommended for gravity filtering.) They even carry reasonably-priced hobby filter packs and kits! How nice! Finally, if you are in the market for bottles, whatever bottle you're hoping for is probably in this selection. You must place your order by phone, but I would not skip looking through the catalog, if only for education. The PDF Catalog can be found here.
www.bascommaple.com – The used buckets and lids (at very good prices) are the best thing about this site, which is otherwise a bit overwhelming in its vastness, at least for this beginner. The spile selection and pricing are decent. The storage tanks are abundant but expensive, save for one reasonably-priced plastic 55 gallon drum. The hydrometer/thermometer section (labeled, confusingly, only "thermometer") and the filter section, which are also ample, come with no guidance; the syrup container selection, which speaks for itself, of course, is vast. The site suggests that shipping and handling fees are added after you pay and notes that there is a 10% restocking fee. All in all, though, worth a look if you know just what you are looking for, are looking for used buckets or are looking for things in bulk or case quantities.
www.leaderevaporator.com - This website is hard to navigate; best to hunt for what you are looking for by using the search function and paying attention to the navigation headings. I bet the catalog is a great read, but, unfortunately, it was in a format that I wasn't able to download. The best thing about the site are the downloadable instruction manuals (which I was able to download). Very educational if you're looking to take your research to the next level. Leader carries a good variety of buckets and alternative collection containers and a couple of hydrometers and hydrometer cups, but no thermometers that I could find. Its line of spiles is more limited, but does include the aesthetically-pleasing, old-fashioned cast ones that carry the company name. Very romantic. Storage tanks are available in several sizes and not outrageously expensive; the site notes that you must call to arrange shipping, though. The filter selection is modest; the bottling selection, adequate. You have to register as a customer to purchase.
wwww.cdlusa.net - This is a giant, professional site geared toward giant, professional sugar makers. But there are some gems, including overall lowest prices on the basics. CDL boasts the best prices on new buckets (listed beside snowshoes in "miscellaneous!") and on spiles (listed under "fittings and tubing"). It does not appear that CDL has a consistent supply of metal buckets, but has a variety of plastic ones, including, excitingly, a gray plastic bucket, the likes of which I've never seen, and which may many-a-marital-argument solve. CDL's prices on its vast array of hydrometers and thermometers (both filed under "measuring tools," "brix" and "temperature," respectively) are also the lowest. Hydrometer cups are listed separately with other draw-off items. Storage tanks are there, but their prices aren't. Yikes. Syrup containers abound and at the lowest prices around. If you prefer it to surfing, leaf through the giant catalog. You have to register as a customer to place an order online.
tapmytrees.com - This site looks like it affords the best online purchasing experience out there for a beginning back-yarder. It is an easy website to navigate where the buckets and spiles are nicely packaged and displayed with other items - like hydrometers and filters - that you might be in the market for. Shipping is free, but you do pay for all this convenience, as the prices are higher, the selection is very limited, and some things that you will need (sap storage containers, pre-filters) are simply not available. Still, if you want to get started with the least possible amount of thought, or are giving a gift to an aspiring beginner, this is a good enough place to pull the trigger; you can see the whole inventory here.
mapletrader.com – Ah, the eBay of maple sugaring supplies! If you are down with used goods, here is where you will get your best prices. There are lots of old galvanized buckets and lids and old cast-style spiles- fewer hydrometers, thermometers and sap storage containers, but it's the kind of site you have to troll for best results. Obviously not a great place to get filters and bottling supplies. But if you are willing to piece it together, totally worth a look! Go to the classifieds here, search for what you are in the market for and you'll see what I mean!
On Teaspoon of Sugar, we write about maple sugaring, maple syrup, starting and running a small business, and living the sweet life here in beautiful, downtown Montpelier, Vermont.