Maple Sap Collection
and Syrup Production

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Background Information:


Maple Cross Section The production of maple syrup has been an activity of early spring since the pre-Columbian era in America. American natives would gash the trees, collect the sap, let it partially freeze to enrich the sap and then boil it down, sometimes by dropping heated stones into the sap.

What Kind of Trees?

Maple that was cut down The trees suitable for tapping include all of the maple family (Aceraceae): Sugar, Silver, and Red Maples as well as Boxelder. Sugar maple trees can be identified by silvery bark that is rough on the lower portions of the tree and horizontal branches. Sugar Maple sap contains the highest concentration of sugar (2% or higher according to conditions). Boxelder produces a weaker sap, but one which is especially delicious to drink as is, tasting like a slightly sweet spring water, and making an excellent base for peppermint tea. Other species of trees may be tapped including walnuts, hickories, Sycamore, and Sweet Birch. Trees to be tapped should be at least 1½ feet in diameter, have large healthy crowns, and be well exposed to the sun.

Materials Needed:


Tapping the Tree

Correct Tapping Angle Drill the tapping hole on the south side of the tree. A northern exposure often will not flow at all early in the season. For commercial spiles, a ⅜-in bit should be used, drilling the hole about 3 feet from the ground, and 1½ to 2 in. into the trunk, with a slight upward slope (as shown in the figure to the right).
Xylem and Phloem Note as you drill that the bark (phloem) is orangish-brown and the xylem is whitish (xylo = wood, phloeo = the bark of a tree). Avoid tapping directly above a lower limb or trunk defect (last year’s tapping hole?).
Putting Hook onto Spile Put a hook on the back of the spile, and tap the spile into the tree with a hammer (as shown in the figure to the left, below). A 3-gal sap bucket is hung from the hook on the spile, but when collecting sap at home where “official” buckets are not available, many variations are possible. (The wire on the lid fits through the hole in the spile to hold the lid on, thus the bucket can be removed without removing the lid.) If tapping at home, gallon plastic milk bottles may be used, but will have to be emptied several times a day during a heavy flow. You may place a 5-gal bucket on the ground if the spile is long enough.

Sap Dripping into Bucket After the bucket is hung on the hook but before the lid is attached, count the number of drops per minute each bucket is dripping. This may be done by counting the number of drops in 30 sec and multiplying by two.

Hanging Bucket on Spile The flow of sap is highly dependent upon weather conditions. Optimum conditions are nights in the lower 20° F range followed by bright sunny days in the 40° F range. The flow will stop when daytime temperatures do not go above freezing, or when night temperatures do not go below freezing. The flow usually lasts roughly three weeks (more if it gets warm in January, but the holes may heal shut and need to be redrilled). While it flows, collect daily in late afternoon (5:00-ish is a good time — any earlier and you won’t get all the sap from that day, later and you won’t be able to see what you’re doing. You will not get credit for sap collected before 4:00 at the very earliest). Note that normally xylem carries water up from the roots and phloem carries the sugar produced by photosynthesis down to the roots to be stored. The latter is especially true in the fall. In the spring, the xylem has the unusual job of carrying stored sugars up to the developing buds, and it is this flow that we tap and harvest.

Sap Collection

  1. Obtain a collection data sheet and record weather conditions and time of collection.
  2. Starting at the farthest tree first, at each tree level the bucket on the tree and measure the depth of the sap by inserting the meterstick to the bottom of the bucket. Record the depth on the collection data sheet. If the bucket is empty, so indicate.
  3. Pour the sap into the collection container (carboy on the backpack) and replace the metal bucket on the hook so that it hangs straight and the cover is in place. Place the lid on the backpack carboy and proceed to the next tree.
  4. Continue measuring and recording the depths of sap in the metal buckets and replacing the buckets until all trees have been visited. If the backpack becomes nearly full before you have finished all the trees, cover it securely with its lid and return to the reservoir (“garbage” can) at the school.
  5. After all sap has been collected (or if you’ve returned with a full backpack and still need to go collect more sap), measure the depth of sap in the backpack and record on the data sheet (do this for each load if more than one trip is made).
  6. Pour the collected sap into the “garbage” can and determine the depth of sap in the “garbage” can, recording this number on the data sheet as well. If necessary, return to collect the rest of the sap. Collected sap may be held in the “garbage” can if the temperatures do not go above 40 to 45° F. If the temperature is warmer than that, the sap will support bacterial growth and spoil. Normally, the “garbage” can should be left in the designated location overnight, and lab staff and/or sap-boiling “babysitters” will bring it to the lab the next morning to boil down the sap.
  7. Carefully store equipment so that various instruments are hidden behind the “garbage” can, securely cover the “garbage” can with its lid, and take the completed data sheet with you. Make sure to indicate weather conditions, times of start and finish, and any comments relating to conditions of equipment, etc.
  8. Make copies of the data sheet for the lab notebooks of the two people who did the collecting and turn in the original to Ms. Carter to receive credit for collecting. Ms. Carter will be entering all sap collection data into the computer (unless you help out by doing it yourself), and the points you receive will be based on those data.


The evaporator may be any large, shallow, metal pan which may be heated. The larger the surface area of the boiling sap, the more rapidly it will evaporate. The boiling down requires a great deal of energy. A LARGE baking pan on top of the stove will suffice. However, due to the flavor imparted to the syrup, wood is the fuel of choice. A special wood-fired “Fankhauser” model evaporator may be fashioned from an inverted clean garbage can lid and a 5-gallon can with bottom removed (rusted-out, for instance). Cut a 4×4 in. hole near the top of the can for smoke release.

Stand two large firebricks up to form the fire box and place the can on top, with smoke hole up and away from where fire is to be stoked. Place the garbage can lid on top (upside down) and stabilize. Partially fill with sap and level lid by moving on can. Fill with sap to within ¼ in. of top and stoke up a good fire. The lid will hold around 2½ gal of sap which should be removed to a saucepan to finish off. During the last few minutes, watch it “like a hawk” as it will burn very easily at the last minute, ruining hours of boiling (and your mood). The finished syrup should have a specific gravity of 1.37 and boil at 104° C (219° F). When it is nearly-done, it will have “oily”-looking bubbles, and when it’s ready, foamy bubbles will start to rise in the pan. If you want maple sugar, heat until it boils at 112° C (234° F). (Here in the lab, we will be using whatever sources of heat we can find — gas and/or electric. About 40-60 gallons of sap are needed to make one gallon of syrup when boiled down.)

The resulting syrup should surpass your expectations. It is very rich and will go a long way. Try it on cornmeal waffles with butter. It is the real thing. (Note: there is a Clermont College tradition of having a waffle breakfast on the first or second Friday of April with maple syrup from sap collected by biology lab students.)

Some Further Notes on Collecting:

If you sign up to collect sap, you better be there unless you can agree to get someone else to take your place and do it. A sign-up calendar has been placed online, and if your name is there, you better be, too. If someone takes your place, his/her name needs to appear in place of yours (let Ms. Carter know ASAP). If sap is not collected on a given day, that causes problems (like overflow) the next day. No points will be given for sap collected too early in the day. Sign up for sap collection in pairs. Both partners will receive the following points for sap collection:
weekdays, first trip — 5 pts each person
         (second [or more] trip if needed) — 5 pts each
weekends (Sat & Sun), first trip — 10 pts each
         (second [or more] trip) — 5 pts each

If one person doesn’t show and the other has to do it alone, that person gets all the points. If no one shows up and sap is not collected, both people get 5 points deducted (–5 pt). On the other hand, if the weather is REALLY cold and there is no sap flow, you don’t need to come in to check it (and won’t get points for an obviously futile hike) — if in doubt, check with Ms. Carter or Dr. Fankhauser first. Please be considerate of others when signing up for sap collection and don’t sign up for more than your share of days. If you sign up for too many days, some of those times may be canceled in favor of other students who wish to collect but have limited scheduling options. If you have someone other than Ms. Carter for lab, your instructor will be notified of the points you have earned based on the online data.

Copyright © 2004, 2015 by J. Stein Carter. All rights reserved.
Based on printed protocol and background information
Copyright © 1981 D. B. Fankhauser
and additional information © 1992 J. L. Stein Carter.
Chickadee photograph Copyright © by David B. Fankhauser
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