Reader Question: Filtering Maple Syrup?

by Tig Tillinghast

A reader: I just started sugaring this year. I have looked at library and have a “maple mentor” but can’t seem to filter out the sand on the bottom on my own. One book from library said to make filter/cheesecloth hot with water before filtering and then filter/can. I did this with one batch and it looks great, but all of this lumpy sugar stuff was left behind on the filter. So I have been just dry filtering with several different materials, and now they all leave the sand at the bottom. What else can I try and was the library book right? Hot water on the filter? It just seemed to be leaving behind an awful lot of things.


Making the filters hot with water is very useful (especially if you use hot sap from the evaporator, which doesn’t dilute things quite as much) when using a filter press. The correct terminology for filter presses, by the way, is “damned filter press,” but “filter press” will do as an abbreviation. The filter press is a device that forces maple syrup through a series of plates that alternately have paper filters and often a white power substance called filter aid or diatomaceous earth. Those paper filters tend to break when pressure builds up from too much sugar sand building up or the maple syrup lacking enough heat to run quickly through the machine. That’s why preheating the filter with hot liquid can allow you to get much more maple syrup through the filter press.

[The Damned Filter Press]

Now, with a gravity filter system, such as the one you’re using, where you just let the maple syrup run through a cloth, there does not seem to be any benefit from pre-wetting the filter. It sounds to me like your problem is that you are using a cloth that is too coarse to filter much of the sugar sand. Cheese cloth is only good at filtering out the very largest of chunks. In order to get your maple syrup at all clear, you’re going to have to use either a wool filter or one made of a synthetic wool, such as Orlon.

We use cloth diapers as a first filter, drawing it through the diaper right off the arch. We tried cheese cloth, but it was simply too course a filter to take much out of the solution. As a final filtration step, we use the filter press to polish the maple syrup, taking out pretty much all the very fine particulate matter left in the maple syrup. By using the course filter of the diaper first and by pre-heating the filter press, we get much more maple syrup through the filter press before having to break it down, clean it and then set it up again.

I do not recommend that folks with small operations get a filter press. They are argumentative, balky, stubborn, capricious machines with personalities akin to the staff at your local DMV. People buy them because they’ve grown in maple syrup production past the point where gravity filters can keep up with the maple syrup produced. I miss those days when our trusty gravity filter kept up with our arch.