Filtering is what turns cloudy, gritty syrup into the clear, golden syrup you see in stores. It's simple, but it has one golden rule: filter while the syrup is hot. Here's everything you need to know.
What is sugar sand?
As sap boils down, natural minerals in it (mostly calcium compounds) come out of solution and form a fine, gritty sediment called sugar sand or niter. It's harmless, but it makes syrup cloudy and gives it a gritty feel. It also settles as sludge at the bottom of jars. Filtering removes it.
The two-stage filter: Orlon plus Reemay
Maple producers filter in two layers, and it works just as well in the backyard:
- Orlon filter (the main filter): a dense, 16 oz polyester felt that catches the fine sugar sand and polishes syrup clear. The felt is made from food-contact compliant polyester (FDA 21 CFR 177.1630) and is BPA-free. It's reusable for years with good care.
- Reemay prefilters (the first layer): thin sheets of Reemay spunbond polyester that sit on top of (or inside) the Orlon. They catch most of the heavy sediment first, so the Orlon stays cleaner and the syrup keeps flowing. Reemay is a food-contact material that meets FDA regulations (21 CFR 177.1630).
| Cone filter | Flat filter | |
|---|---|---|
| Shape | An 8 quart felt cone that hangs over a pot | An 18 x 18 inch felt sheet that lies in a flat filter tray |
| Prefilters | Nest inside the cone | Stack on top of the felt |
| Best for | Small batches and simple setups | Faster filtering that's easier to keep flowing |
What you'll need
- An Orlon filter: a cone, or a flat sheet with a flat filter tray.
- Reemay prefilters to match (recommended).
- A way to hold the filter over a clean pot: a filter rack, a frame and clips, or a flat filter tray.
- A clean pot to catch the filtered syrup, and a thermometer.
How to filter, step by step
- Set up before you finish. Hang the cone (or set the flat tray) over a clean pot so it's ready the moment your syrup is done.
- Dampen the filters with hot water and squeeze out the extra. Don't wring them. Damp filters get syrup flowing faster, but they shouldn't be dripping.
- Add the prefilters. Nest Reemay prefilters inside the cone, or stack them on top of the flat Orlon so they form a shallow bowl up the sides of the tray.
- Pour the syrup in while it's hot, right off the heat. Hot syrup flows through easily. As syrup cools below about 180°F it thickens and filters very slowly.
- Let gravity do the work. Don't squeeze or wring the filter. That forces sugar sand through and can damage the felt.
- Lift out the top prefilter when the flow slows to a trickle. It's full of sediment. Keep pouring through the next layer.
- Check the result. Filtered syrup should look clear when you hold a jar to the light. If it's still hazy, run it through again while hot.
Tip: Put a small permanent-marker mark on one corner of a flat Orlon filter, and always set it in the tray with that corner in the same spot, same side up. Any sugar sand left in the felt after rinsing stays on the "dirty" side instead of washing into your next batch.
No filter? Try settling
If you don't have a felt filter yet, you can let gravity separate the sugar sand:
- Pour the finished syrup into a tall, clean container.
- Let it sit, covered, in a cool place for 12 to 24 hours. The sugar sand sinks to the bottom.
- Carefully pour the clear syrup off the top, leaving the sludge behind.
- Reheat the clear syrup to bottling temperature (185°F to 190°F) before bottling.
Settling works, but it's slower and wastes a little syrup. An Orlon filter gives clearer results.
Filter the sap too
Filtering doesn't start at the end. Pouring sap through a cheesecloth or strainer as you collect it keeps bark, bugs, and debris out of your pan in the first place.
Caring for your filters
- Rinse in hot water only, before and after each use. Never use soap or detergent. Felt holds onto soap, and it will flavor your next batch.
- Rinse from the outside in to push sediment back out the way it came.
- Don't wring. Press out the water and dry completely before storing, to prevent mold.
- Store in a clean, sealed bag away from strong odors. Felt picks up smells.
- Replace prefilters when they're worn or won't rinse clean. A well-cared-for Orlon filter lasts for many seasons.
Reemay is a registered trademark of its owner.
Ready for the next step? Read How to Bottle and Store Maple Syrup, or go back to How to Finish Maple Syrup.