Filtering tips for crystal-clear syrup

ANTIGO, Wis. — Watch the filter “cake.”

That’s the advice from Jim Adamski of Adamski’s Sugar Bush in Antigo, Wis., a CDL dealer and president of the North American Maple Syrup Council.

“If you’re using too much DE, the cake will be solid as a rock,” Adamski said. “If it crumbles and breaks apart, you know you used too much.”

Diatomaceous earth, or DE, is the filter aid that removes niter and other solids. Too little or too much can cause problems.

After running a filter press, producers should see a firm, beige cake between the plates.

Early-season syrup typically filters easily. As the season progresses, more DE is often needed.

When syrup turns stringy or ropy, filtering will not correct the problem.

“If you get to that point, you need to stop boiling,” Adamski said.

Scott Dunn of Dunn Family Maple in Buxton, Maine, said the proper amount of DE varies.

“I can’t tell you how much DE to use,” Dunn said, during a recent seminar to Maine producers.

At his farm, he uses more than 25 coffee cups of filter aid per batch in his 7.5-inch Leader press.

As for filter papers, “keep them dry,” he said.

Sugarmakers using newer vacuum presses connected to Shop-Vacs should still use DE, he said.

Special note on diatomaceous earth

DE is also used in gardens to control slugs.

It is made from the microscopic, fossilized remains of aquatic organisms called diatoms.

Their jagged silica skeletons can scratch slugs’ mucus membranes, causing them to dry out.

Because DE is abrasive and can irritate the respiratory tract, producers should minimize dust when mixing, wear eye protection and use a respirator or dust mask, according to Jason Lilley of University of Maine Cooperative Extension.

Also, very important to note, do not just go and buy DE at the farm store. Make sure to buy it from a maple dealer. There are different types of DE and the type used for maple is food-grade.

Hardware store DE is often not.