I have a 20 gallon stainless steel container that I evaporate sap over an open fire with. Boiling point of syrup is 219*F and the specific gravity is between 1.3-1.4 (can't remember the exact #). Basically how I do it is boil the sap down, stirring,skimming and adding more sap constantly.Once it is reduced down, just prior to boiling at 219, I bring it in the house and finish it up on the stove. Some people finish it over the fire, but it is tricky...the syrup can get scorched or just keep reducingdown to a sugar block. Once in the house and it reaches 219, I strain it through cheesecloth and bottle it. You have to bottle it hot or it can spoil...I think the magic temp for sealing is 180*F. I didn't make any syrup this year, crappy sugaring season. I usually make 2-3 gallons a year for friends and family.