I put 6 test taps in our black birch today, and it started flowing. I've still got maple going thru our 2 x 6, we'll have to light our old half pint for the birch sap. I made some last year, the trick is to bring it half way in the regular evaporator, then the rest of the way using something easy on the heat, like a double boiler, the sugars in birch burn at the boiling point, so it's a long slog to remove water content, gently steam it away, no boiling. -DavidSB