Rusty is right, you have to filter it up to temp or it will not flow. We filter when pulling from the evaporator syrup pan into the finisher, then again after the finisher into the canner. We normally stack felt on the bottom, 2 or 3 filter papers on top. As it flows through and clogs we pull the filters to the side to get the flow through clean again. If it clogs completely before everything is through, pull off one of the papers.
If you should finish it but wait a day or two before canning it, bring it up to temperature and filter again. Every time you heat it it will precipitate out more of the minerals. I've been told it's mostly calcium.
Here is where we get most of our supplies, Sugar Bush Supplies Mason, MI
Then; maple milk shake, maple broiled scallops, maple baked beans, maple vinagarette salad dressing......