Quote Originally Posted by Bucksaw View Post
...could you just use regular coffee filters? Stack a few of them on top of eachother to a better filter or are they too porous?
No. They can work with very thin watery concentrate but don't work well at all for final filtering. You'd need several lifetimes/gallon

Here's something I came across yesterday in a 1960's copy of the Maple Sirup Producer's Manual that might help those who filter, particularly the last paragraph....

When a finishing pan is used, the sap being drawn from the evaporator for
transfer to the finishing pan need not be of constant density. It can be any density above 45° Brix (3° or more above the boiling point of
water). The higher the density of the sirup that is withdrawn from the evaporator, the smaller the amount of liquid that has to be evaporated in the finishing pan.

Another and important advantage of using a finishing pan is that it permits filtering the sirup that is being transferred from the evaporator to the finishing pan. Sirup at this density (45° to 60* Brix) has essentially all of it's sugar sand (see pg.78) precipitated. At this density, it has a viscosity (fluidity) only slightly higher than water and filters much more readily than does standard density syrup.