How to Filter Sap
Before your maple syrup is finished, the sap will be filtered three times to remove debris and niter, also called sugar sand. This is an essential part of making maple syrup but each filtering step is quick and easy and this article will show you how to do each one. Important to note, though, in Steps #2 and #3 you must use professional filters designed for syrup making. These are inexpensive and reusable so it’s a one-time purchase as you get started. (Filters are included with many of our kits, click here to browse). In Step #1, a few layers of cheesecloth or a thin cotton dish towel works well BUT it must be rinsed free of laundry soap or detergents.
A quick aside: If you’re making black walnut syrup, don’t use the Orlon or a similarly thick filter. Walnut sap contains more pectin than maple sap so it’s too thick to run through this type of filter. Try cheesecloth or a thin strip of clean muslin.
Filter #1: This step is done each day as you collect sap to remove debris that may have fallen into your sap bucket (one more reason to use a closed lid system!). Suspend layered cheesecloth or a cotton dish towel over a bucket or line a colander with it and slowly pour the sap through to seine out debris and other undesirables. When done, rinse this filter material with plain hot water, air dry, and save for later. Refrigerate the sap until ready to boil.
Filter #2: This step occurs midway in the boiling process as sap reaches a temperature in the 216°F range. At this point, concentrated sap is moved from the larger pan or evaporator and poured through a thin prefilter into the finishing pot. This removes the majority of sugar sand which can make syrup cloudy.
Filter #3: The third and final filter is done after the sap has reached its finished temperature and is poured into bottles. For this filtering, put the thinner prefilter inside the thicker Orlon filter and moisten with hot water. After all the water has dripped through, pour the finished sap through these filters. Syrup is now done and ready to bottle (or eat!).
Hot syrup will filter quickly so handle carefully. Some people skip this step and just let the syrup sit in the refrigerator or snowbank for 24 hours so the sediment settles to the bottom – this does create more waste and you’ll need to reheat your syrup before bottling it.
Cleaning Filters. As mentioned earlier, these filters are reusable and should last for years if cared for properly. Never wash with detergent or dish soap as this can affect the flavor of finished syrup. After use, simply rinse well in hot water and hang to dry. Be careful with the thicker filter to not wring it out or stretch it out of shape.
If you’d like to learn more about entire boiling process, click over to this helpful article, “How to Make Maple Syrup.”